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Environmental Analytical Chemistry - Science topic

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I was interested in conferences in the field of environmental analytical chemistry, which will take place in 2022. I have found a number of conferences called "International Conference on Chemical and Environmental Science (ICCES)", which will be organized. An example is this conference in Estonia:
I assume that this is a suspicious conference. The table with deadlines also looks strange. In terms of the volume of conferences, it resembles WASET, which is discussed here and on other sites. However, does anyone have a personal experience with the organizer - iser.co?
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Be careful with this one. ISER is mentioned in the list of questionable conferences: https://libguides.caltech.edu/c.php?g=512665&p=3503029Another directly observable disturbing things is:
-If you scroll down http://iser.co/Conference2022/Estonia/1/ICCES/you see besides pointless logo’s some well-known misleading metrics like DRJI and CiteFactor, these are often used by predatory publishers (see also: https://beallslist.net/misleading-metrics/)
-If you click on publication http://iser.co/publication.phpit is full of journals/publishers mentioned in the Beall’s list, for example:
​-“International Journal of Advanced Computer Research” (published by ACCENTS Journals)
-“INTERNATIONAL JOURNAL OF PUBLIC HEALTH AND EPIDEMIOLOGY” (published by International Scholars Journals)
-“Global Scholars Journals”
-“UNIVERSAL JOURNAL OF EDUCATIONAL RESEARCH (SCOPUS INDEXED) SCOPUS” (published by Horizon Research Publishing, hrpub), some journals are indeed Scopus indexed but three of them already discontinued after 2-3 years
So, I would say too many warning signs.
Best regards.
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Dear to whom it may concern,
I have been developing a solid phase extraction-based sample preparation method for environmental samples.
I would sincerely like to ask you about the SPE process namely that after loading the samples onto SPE cartridges, I am wondering which next steps will be carried out:
1. Rinse these cartridges with the weakest elution strength solvent (for example, water or water with 5% MeOH for C-18 SPE adsorbent), Or
2. Dry these cartridges under nitrogen stream for 15 or 30 mins, Or
3. Do both of the steps in order: rinse these cartridges and then, dry them.
In case of drying these cartridges, how long should the step be carried out? As far as I know, some compounds can be more strongly trapped onto these cartridges, leading to their low recovery if the step last for a longer time.
I hope that you may spend a little time helping me clear the inquiry.
Thank you so much.
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Thanks for your interest. I would suggest you to follow the first step: Rinse these cartridges with the weakest elution strength solvent (for example, water or water with 5% MeOH for C-18 SPE adsorbent). Alternatively, you may try with 10% MeOH in ethyl acetate and then you may add Hexane.
Good luck
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Dear to whom it may concern,
Based on ChemAxon, I calculated pKa values of Acesulfame as follows:
1. pKa (Strongest Acidic): 3.02
2. pKa (Strongest Basic): -6
Because I would like to convert Acesulfame Potassium into Acesulfame, I intend to use a stronger acid such as HCOOH or HCl than Acesulfame to do this conversion.
I am wondering whether this approach will really work or not.
May you please share your opinion with me?
Thanks in advance,
Quynh Khoa Pham.
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Quynh - I found a detailed description of the procedure for converting acesulfame potassium into acesulfame. It is published in a paper entitled "Polymorphism in acesulfame sweetener: Structure-property and stability relationships of bending and brittle crystals" which was published in Chemical Communications 2010, 46, 2562-3564. The Electronic Supplementary Information (ESI) is available free of charge (see attached).
Neutralization of Acesulfame potassium (Ace K)
It was obtained from Sigma Aldrich at a stated purity of 99% and no attempt was made at further purification. Ace K (5 g) was dissolved in water (5 mL), neutralized with concentrated HCl (5 mL) and achieved the highly acidic solution of ~ pH =2 and extracted with ethyl acetate (15 mL). Up on routine work up afforded a white solid of salt free acesulfame. It was crystallized from EtOAc by slow evaporation at the ambient conditions. Needle crystals were yielded. Mp: 122- 124 °C.
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Dear to whom it may concern,
I am investigating carbonaceous materials to treat aqueous samples but I have no knowledge of these materials.
May I ask you some questions as follows?
1. Whether these materials possess both polar and non-polar interactions
2. May you please show me mechanisms by which we can explain why these materials have the above properties?
Thank you so much.
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Hello and thanks in advance!
I'm trying to separate an amino acid standard, but have been only seeing 2 peaks, one internal standard (ABA) and one broad peak around 17 minutes. 
I've been using the same conditions as Liu, J. Chromatog. A, 1994, 670, 59-66, basically, using 6- AQC to derivitise,
wavelength at 248 nm,
Waters Eluent A as eluent A and acetonitrile and water as eluent B,
run time of 46 minutes,
flow rate of 1 ml/min,
C18 AccQ.Tag column.
I'm stumped as to why this is happening. Thanks for any help!
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find info in above mentioned link
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This is the third call for applications for Short Term Scientific Missions (STSMs) for grant period 2 of the COST Action CA17136 - INDAIRPOLLNET (https://indairpollnet.eu/). STSMs are institutional visits aimed at supporting individual mobility, fostering collaboration between individuals. These missions contribute to the scientific objectives of COST Action CA17136 - INDAIRPOLLNET. They are particularly intended for young scientists. The selection of applicants is based on the scientific scope of the STSM application which must clearly contribute to the overall objectives of the Action CA17136 and be related to a specific Working Group. Interested researchers can apply by following the instructions provided in the attached document and submitting their application and supporting documents until 31 January 2020.
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anything related to India then I am really intersted
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Air quality analyst, chemists etc.
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Carbon disulphide has a very high desorption efficiency. In addition, it has low sensitivity to FID hence its wide use as an extraction solvent for many organic substances adsorbed to activated carbon
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Which one is more suitable to measure heavy metal uptake by aquatic plants.
Can anybody provide me these 2 equations with references? 
Regards
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Bioconcentration factor (BCF) can be expressed as the ratio of the concentration of a chemical in an organism to the concentration of the chemical in the surrounding environment. BCF is expressed in units of liter per kilogram (ratio of mg of chemical per kg of organism to mg of chemical per liter of water).
National Bioaccumulation Factors - EPA
BAF=Cshoot/Csoil; Cshoot and Csoil are metals concentration in the plant shoot (mg/kg-1) and soil (mg/kg-1), respectively. BAF was categorized further as hyperaccumulators, accumulator and excluder to those samples which accumulated metals>1 mg/ kg-1, and < 1, respectively
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I have a solution of both Peroxydisulfate (S2O82-) and Hydrogen Peroxide, and most methods used to detect Peroxydisulfate (S2O82-) interfere with H2O2 because of the similar O-O bond. How can we quantify one without the interference of the other?
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Dear Ali,
there were several papers in which detection of peroxydisulfate and peroxymonosulfate was achieved by ion chromatography and HPLC, probably by this you could distinguish between h. peroxide and PS.
Please see:
Moreover, one chapter in this review is devoted to the determination methods of PS:
Regards,
Stan
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Determination of trace concentrations of phenol in aqueous solutions.
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this link is useful
ttps://onlinelibrary.wiley.com/doi/pdf/.../3527600418.bi10895e000...
regards
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I'm looking for a relatively simple analytical method (colorimetric analysis etc.) for measuring methanol in aqueous solutions in the concentration of about 100 µM ?
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I have tested this method for methanol production from PEC reduction of CO2. provided the quantity of of the methanol is high enough to an extent it is measurable by this method, then its good to follow. But from my experience, methanol produced from CO2 reduction was not detectable by this method..but GC does.
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Hi all, I was looking to confirm whether it is necessary to acidify a solution sample prior to AAS (to measure the concentration of a metal in solution).
I ask this as I am working with bacteria which may or may not have the capacity to precipitate cadmium. I was hoping to detect cadmium precipitation in a culture supernatant by comparing the Cd concentration of a strong acid-digested supernatant sample (revealing total Cd in sample) to a non-acid digested sample (revealing only soluble Cd).
Ideally if bioprecipitation is present, the acid-digested sample would would have a much higher Cd concentration than the non-digested sample. The difference in Cd between the two readings would represent the Cd that has been precipitated into an insoluble compound (eg. cadmium carbonate, cadmium sulfide, etc).
However if samples need to be acidified prior to AAS in the first place, the above logic will not hold true.
I really appreciate any help with the above question, if I am not explaining the problem effectively please let me know.
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Hi - this is a good question. The problem with AAS is that you need a solution free of ppt. So - will you filter out the ppt first or are you expecting that the Cd will not atomize if it is in a ppt? As long as your samples are in plastic containers loss of Cd to the glass container will not occur. Acidification prevents growth and the formation of ppt. So no you do not need to acidify but you do need to filter.
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When pH of the solution change ORP value also change or not. What happen the pH of water when ozone is dissolved into water
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I will gratuitously seize this opportunity to slide in a side-question about correlating ORP+pH+Temp to aqueous H2S concentration in groundwater.
A sensor manufacturer suggested that H2S concentration could be inferred from measured values of pH+ORP+Temp sensors and calibrated against H2S concentration.
Is this plausible and if so, what is the essential technique ?
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I am using the standard in the form of mixture i.e EPA VOC Mix 2 (2000 microgram per ml each component in methanol). As mentioned in COA, it is having 14 components / analytes. When this particular mixture was run on HPLC, it did not give all 14 peaks of different components. It gave only one broader peak with some minute peaks. The mobile phase utilized was Acetonitrile : Deionized Water. Why separate peaks were not being identified? What should be done / Which parameter of HPLC should be altered so that separate peaks could be identified?
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Please first make sure the column is clean running only the mobile phase. the broad peak might be column contamination. then I suggest running a standard with known retention time, there are many variables involved. including the system (column, pressure, mobile phase) and sample purity. better to trouble shoot step by step
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Three specific aldehydes seem to appear in all analyses of VOCs in ambient air or from material emissions. Can the occurrence of nonanal, decanal, and benzaldehyde be explained by degradation of the adsorbent polymer? These are always observed by some, ignored by others. There is no consensus on their origin or relevance. Can anybody shed more light?
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Dear Finn,
Benzaldehyde is definitely a Tenax TA artefact and can with some generous assumptions be explained on the basis of the Tenax structure. As you know. ozone and OH promotes its formation.
The aldehydes, by nature, cannot be explained on the basis of the Tenax structure. Nevertheless, they are observed, usually in an uncontrolled way. My theory is that they are artefacts from traces of skin oils and the like.
I also attach a recent paper I believe might interest you.
Best regards,
Peder
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Calcium carbonate can form both through chemical precipitation in water column and dissolution of organic shells. So how can you differentiate between these two sources from total carbon and total inorganic carbon data?
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Thank you Dr. Towe for the information.
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I am a PhD student at UPC (Spain) and I need some thermodynamic data, and my directors asked me about MEPHISTA and getting the information in order to understand some fission products behaviour but I don't know how to get them.
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I am about to start a method for the analysis of aromatic amines in waste water samples after a derivatisation step. So, I was wondering, which will be the best column to give a low detection limit of between 0.01 to 1ug/l.
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Dear Oritsejolomi,
the detection limit does not depend on on the column type, but on the detector. GC/MS is highly sensitive so low detection limits should be feasible. you can use silica or more unpolar DB5-MS standard column. see e.g.
Best,
Christoph
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What is the procedure for this analysis? Including sample preparation.
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I am working currently with wheat straw. To get the compositional analysis of the material, I am using the procedures that can be found in this link:http://www.nrel.gov/bioenergy/biomass-compositional-analysis.html
I hope it helps you to solve your problem.
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I am considering vapour-liquid and liquid-liquid equilibrium between water and hydrocarbon phase. I am getting correct water dew point for aqueous phase containing salt by equating fugacity of components in vapour phase with fugacity/ activity of components in liquid phase after due reduction in liquid mole fraction because of addition of salt. However when I am calculating liquid-liquid equilibrium between aqueous phase and liquid hydrocarbon phase, reduction in liquid mole fraction because of addition of salt leads to wrong values. Does salt concentration effect in water for liquid-liquid equilibrium only limited to the change in activity coefficient of water because of addition of salt and should we not consider the reduction in liquid mole fraction pf aqueous phase because of addition of salt while calculating liquid-liquid equilibrium?
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It depends on how much salt you add.  The change in the activity coefficient of water is great if you add salt, but that does not change the mole fraction of water in the water phase all that much (answer to your last questions).  More importantly, you should consider what type of hydrocarbon phase you are using.  All hydrocarbons are not the same, and salts can for ion pairs in some hydrocarbon phases to a larger degree than others.  If the hydrocarbon is a petroleum product (organic mixture), there are often polar groups on some many of the components that salts can interact with.  Regarding Kai's comment, he is correct about the "salting-out effect".  If you have some polarity in the hydrocarbon phase, this will allow water to dissolve extensively in the hydrocarbon (the amount of water in octanol at mutual saturation is about 2.3 Molar).  Adding salt to the water increases the affinity of the water phase for water, and the amount of water in the hydrocarbon phase will be much less.  Hence, adding salt to a liquid-liquid extraction often results in a better extraction of an organic solute because it makes the hydrocarbon phase more hydrophobic, makes the water phase more hydrophilic, and tends to brake any emulsions that form by keeping the water in the water phase.
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I gone through some books regard to green house gases... in some books they are pointed that, SO2 is indirectly contribute green house effect... and in some books they are not pointed SO2 regard to Green house gases.. So.. I am in confusing ... so I need clarify.. so please....
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Thank you sir for answer but in the following link
they telly that, 
In general terms, the largest contributor to global warming is carbon dioxide which makes it the focus of many climate change initiatives.  Methane and nitrous oxide contribute to a smaller proportion, typically <10%, and the contribution of f–gases is even smaller (in spite of their high Global Warming Potentials) at <5% of the total.
Also reported are four indirect greenhouse gases:
Nitrogen oxides (NOx)
Carbon monoxide (CO)
Non-methane volatile organic compounds (NMVOC)
Sulphur dioxide (SO2)
Nitrogen oxides, carbon monoxide and NMVOCs are included in the inventory because they can produce increases in tropospheric ozone concentrations and this increases radiative forcing (warming of the atmosphere). Sulphur dioxide is included because it contributes to aerosol formation which can either warm (through absorption of solar radiation on dark particles) or cool (from forming cloud droplets and reflecting radiation) the atmosphere.
What is your opinion...
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SOA formed in the chamber experiment was collected on filter paper and extracted in methanol using orbital shaker. Now extracted is required to dry, how it can be done using nitrogen.
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You need a stream of dry N2.  Th e gas can be dried, e.g by passing it through a glass container immersed in a cold mix like dry ice/acetone solution.  The dry gas can be warmed through a glass coil in a waterbath before use.
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i do not get a clear understanding on the procedure i should follow in order to analyse heavy metals in an anaerobic digestion sludge, using AAS
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First, use acids to digest your sludge sample. Secondly, filter the sample or use centrifuge to remove solid particles. Thirdly, collect the particle-free liquid and submit it for AAS analysis.
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I was measuring radon with AlphaE (product of Saphymo)
On the screen, the "NOISE" response appeared.
I tried to start another measurement but the "NOISE" was still on it during several days...
I could not find sufficient info in the instrument manual...
Many thanks for your help
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I fear Paula and coworkers mismatched the instrument's type, AlphaE is battery powered an with at least under that profile it seems to be very, robust.
As to "NOISE", I never saw that message, having used the instrument in several environments with high acustic noise, high humidity and so on.
A first question is: are you sure your instrument is measurring only radon or could be present other dispersed isotopes in air?
Another source of noise in the detector could be mechanical vibration, which could be or even not, induced by acustic noise since the instrument is very light.
The issue is enteresting, if I have news I'll write.
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The digestion methods for plant materials are many. Which method may be the best
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Hi Dear Dr. Barbooti
Please read our article entitled: Comparison of the Level of Cadmium and Lead between the Cigarette  
Filters of Different Iranian and non-Iranian Brands" which we determined the heavy metal contents by Atomic Absorption Spectrophotometer.
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I want to measure the key nutrient levels such as nitrate, nitrite, phosphate, ammonia and silicate in the coral reef waters directly on the field. Please suggest me a reliable device suiting my purpose.
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Dear Guillermo. Thanks for your response and the information.
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I am currently trying to narrow down which set of salts (AOAC, EN, Original) should be used to extract imidacloprid residues from dairy cattle manure using QuEChERS method, as well the sorbents to be used for cleanup using d-SPE. Our initial extractions using just acetonitrile and water (80/20) yielded a dark, yellowish-brown liquid. Samples are to be run on HPLC after extraction. Any comments would be appreciated! 
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If the cow manure is dry then you need to hydrate the sample prior to QuEChERS. We take 3 grams of a dry sample and add 12 mL of water prior to extraction.
My procedure is to add the water to the dry sample and mix well (shaking). Add 15 mL of acetonitrile with 0.1% acetic acid and shake well. Add the QuEChERS extraction salts (I prefer the AOAC method) and shake well. Centrifuge to separate the phases. 
Imidacloprid will not be lost on GCB, so you most definitely want to use PSA/C18/GCB for cleanup. I am assuming that you are using LC-MS, not GC-MS. If so, you should be able to see <10 ppb of the imidacloprid in the cow manure using this method.
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Can anybody let me clear or describe the way to get answer of above mentioned questions? I had matched the result of our samples from online search NIST/EPA Library and identified our compounds.
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To calculate the isotope distribution there is another valuable tool on the web:
the Isotope Distribution Calculator and Mass Spec Plotter from Scientific Instrument Services
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I want to estimate the non-carcin risk for a group of heavy metals using US EPA method of HQ. One of the metals is Fe (Iron), my problem is that I couldn't get the RFD value for it? Any suggestions? Thanks
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 (RfD) (mg/ Kg/ day) for elements reported in literature:
Fe (0.700 ), Mn (0.014), Zn (0.300), Cu( 0.040), Ni (0.020) ,
Cd( 0.001), Pb (0.0035).
 Find attached Table:6 of the following reference
Chemistry Central Journal
December 2011, 5:64
Heavy metals health risk assessment for population via consumption of vegetables grown in old mining area; a case study: Banat County, Romania
·                            Monica Harmanescu, Liana Maria Alda, Despina Maria Bordean, Ioan Gogoasa,Iosif Gergen
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If we cannot find the complete data on pre-industrial content of heavy metal of a river , what is the best way to deal such situation ?
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To answer your question thoroughly requires some additional information. In case of airborne contamination (e.g. lead and platinum group elements in surficial sediments near highways) or agricultural activities (e.g. fertilizers or soil amendment) a comparison between surficial and deep sediments will yield pre-industrial data(pay attention to comparability of grain size).
in case if stream sediments the situation becomes more complex. Originating from huge catchment areas, generally far upstream, a comparison of deep (local) sediment and overlying stream sediment certainly yields differences in element composition. Also in a sediment series with decreasing element concentrations the lowermost part still could be contaminated and will not provide true pre-industrial data. This occurs in early cultured areas, due to e.g. Roman or medieval mining activities. In contrary, finding higher concentrations in surficial materials is not necessarily due to (anthropogenic) contamination.  Whether or not the surficial sediment is contaminated and to what extend requires discriminating the anthropogenic from the geogenic (pre-industrial) element load at the very same material. Keeping in mind that only the elements in most stable bonding forms (silicates, stable oxides) will survive the processes of rock disintegration, relocation and transport provides a clue to a discrimination approach. Element loads due to industrial processes and agricultural activities occur in less stable bonding forms which are not able to survive the rigid conditions of rock disintegration and fluviatile transport. Therefore, in contrast to geogenic loads, they can be stripped off with rather soft chemical digestion methods, e.g. by methods of sequential elution, leaving the geogenic conc. When we applied these methods at depth profiles of contaminated stream sediments (e.g. River Elbe area, Germany) or following several 100 km from the spill site along the river banks (Tisza; Romania, Hungary) shows constant residual concentrations in the range of ubiquitous sediment background (pre-industrial) values, whereas the contaminants show the well known decrease from top to down (Elbe) or from the spill site downstream (Tisza).
So, in the case of stream sediments I would recommend to use methods of sequential eution like the rather simple BCR method (Ure AM, Quevauviller Ph, Muntau H, Gripink B. Speciation of heavy metals in soils and sediments. An account of the improvement and harmonization of extraction techniques undertaken under auspices of the BCR of the Commission of the European Communities. Inter J Environ Anal Chem. 1993;51:135-151. )
In our studies we used a more elaborated method. You will find it via my Research Gate page (publication on contamination of Elbe sediments  (2013) and Tisza sediments (2006))
Kind regards
D. Zachmann
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Metals in soil are partitioned between the solid and solution phases of soils. In which of these forms are earthworms exposed to the metal concentrations in soil??
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 earthworms exposed to heavy metals(Cu,Ni,Pb,V,Zn)  via the solid phase of soil and via the soil solution both, but in soluble form much higher
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I have an aeration tank and feed it with wastewater. MLSS tests show that the growth is slowly, only 400 or 500 mg/l per day. my tank MLSS is 5000 mg/l and my target is 12000 mg/l.
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Dear Safie,
The best way to achieve the numbers you indicated is to purchase membrane bioreactor (MBR):
In a conventional wastewater treatment plant, the secondary clarifier limits the solids concentration in the aeration tank. Typical mixed liquor suspended solids (MLSS) concentrations are 1,500 mg/l to 5,000 mg/l. The MBR replaces secondary clarification in a conventional wastewater treatment plant.
MBRs separate biologically treated effluent from the mixed liquor utilizing membranes to perform the separation. The membranes allow the purified water to pass through the pores (filtrate), while creating a complete barrier to the passage of any solid greater than 0.4 microns, which includes almost all bacteria and suspended solids. In an MBR, the membranes create a solids barrier and therefore the process is not subject to gravity settling solids limitations, as in conventional clarifiers. MBRs are limited instead by the fluid dynamics of high solids mixed liquor, and the effect on oxygen transfer. Typical MLSS concentrations in MBR systems are 10,000 mg/l to 12,000 mg/l.
For more on this topic, please use the following link:
Hoping this will be helpful,
Rafik
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Can anyone name any treatment plant where Filox has been used for Fe and Mn removal?
Has anyone heard of any place where well water has been an issue with Filox?
Thank you, 
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The literature seems to show there is a degree of dissatisfaction with Filox. If you wish to remove iron and manganese one option is to optimise your process for manganese removal. Once the filter media has a layer of manganese dioxide covering it, the process becomes autocatalytic and pH control becomes much less critical. The resultant MnOmedia will sorb (more) manganese plus iron and a plethora of heavy metals as well. MnOhas surface areas up to 300 m/g depending on the source of the Mn. 
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It is believed that the hydrogen peroxide was higher in the early earth due to the anaerobic conditions, and what is the role for its decomposition for life evolution? I have noticed that many inorganic nano materials were found to have the " peroxidase-like activity" and these materials might be presented in the early ocean. For example,  different type of iron oxide ( e.g. Fe3O4, Fe2O3, FeOOH), CoFe2O4, MnFeO4, MFe2O4 (M=Mg, Ni, Cu), MnO2,  FeWO4 ,FeSe, α-MnSe, FeS, Fe3S4, CuS , CdS, MoS2, and WS2). Is any relation of the oxygen generation and these activity ? 
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Hi Xiaolan,
Please follow the following links and pdf attachment for answer to your query.
Best of Luck
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If one is just given the Henry's Law constant (Kh) and octanol-water partitioning coefficient of a few organic molecules, how can you predict what instrument (between GC and HPLC) would be better suited to analyze each one? 
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both above are right - if these are the only compounds you are interested in then GC may be possible but you usually cannot do a direct water injection for GC so you are either looking at an extraction or using headspace analysis (sucking gas from above the surface of the sample). Either way these 3 solvents are pretty volatile so you will need to usespecialized low temperature gc equipment and/or conditions.  Therefore for these solvents LC may be more applicable but you will need to have it interfaced to an MS of some kind.
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I have been doing GC-MS analysis via SPME for spice volatiles for undergraduate research, using a modern Agilent GC-MS with SPME autosampler. Each injection was preceded by a 2-octanol standard, but over 30 replicates of the standard, peak area varies from approximately 2,000,000 to 76,000,000 area units! It isn't due to fibre degradation; I actually got the worst standard deviation 2 days after a new fibre had been fitted (SD 80% of the mean over 7 injections). Any ideas as to why? Most papers I have found talk about how reliable GC-MS is rather than reasons it may not be. Any papers you can point me to would be great, or some suggestions as to why! Thanks in advance.
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Operating a GC/MSD is not like learning how to use a balance or place a sample in a spectrophotometer. This is a complex instrument which should only be used under the supervision and training of an experienced operator. These devices can easily generate data which is invalid and also be damaged ($$$) in the process.
When correct procedures are followed, GC/MSD is a very reliable analytical technique. A well trained operator experienced in the proper operation of the hardware and use of the software is critical. This is not something that one becomes proficient in after days, weeks or months (some scientists are still not proficient after years). As with all analytical techniques, they require proper training and practical experience running different kinds of samples with both the technique of GC as well as EI for the MSD.
As to your observed variability, there are hundreds of reasons why this could occur and troubleshooting them without any method details or instrumental condition is not possible (Please provide them when asking for help as they are needed to understand your method and analysis conditions). Assume nothing, question everything. You will want to start out with the basics first. Forget about your samples for now. There is no point in running samples if the data output is not consistent. You must first determine if the instrument itself is clean and operating to specification. This is most easily done using a standard PV SOP with appropriate column and sample. Verify the system works perfectly first, get help with this task and with your method so you can better understand the overall system. *You may find a simple leak or loose fitting in the process.
Other Misc Troubleshooting Comments:
Keep it simple and start with the basics.
Please check the operation and settings on the GC and also the MSD (which is a separate inline instrument/device). Review your method settings to insure the temp program used is hot enough to retain, then elute ALL compounds off before the run ends (it must also volatilize all of the compounds too at the same time). Too steep a temp ramp and poor results will follow. Too shallow and you risk leaving material on the column each time. Injector not hot enough, again, sample contaminates the injector and may not make it onto the column. There are lots of places where things can go wrong and I have not even discussed the correct setup of the detector!
Esp review your GC injection settings and conditions (i.e split/splitless, liner type, is the seal leaking?, inj temperature, solvent used for injection....). This is where many people discover problems. Leaks at the injector are common as are injecting samples in the wrong solvent. Check the column flow rate and backpressure. Is the column fouled? Is the column being run at the right temperatures? Is the column appropriate for the method and conditions you are using?
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Dear All,
I need a chemical that I can use to investigate the presence of Fe(IV) in my reaction process. I am wondering if there is a way to detect or refer to the presence of Fe(IV). Thanks
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FeIV exists only as a complex cation. vith diars and Cl-. 
Please explain the case.
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i have be trying to find the COD by using Dichromate and i found that the values of COD are coming in multiples of 4 i.e., 16,32,48,64,96.....which i find very absurd?What may be the possible cause for such results and i also wanted to know if there is any alternative to this?
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Plz refer APHA procedures to avoid as for as possible experimental procedures. If the COD value is very high, dilute the sample and perform the experiment.
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I was not able to find out the complete list of pollution tolerant algae. Please help me in finding out the list. 
Thanks in Advance
Anila Ajayan
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Dear Anila,
I think, you need the copy of the article? i'm attaching for you Palmers article.
Andrey
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Help me please,
i'm looking for a practice validation protocol of PCB analysis method.
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Thank you so much Ariadne and Paul for your responses.
I'm trying to find a validation protocol for the analysis method of organochlorines extracted by Milestone microwave and analysed by GC/ECD.
I want to work on the "Guidance document on analytical quality control and method validation procedures for pesticides residues analysis in food and feed." implemented by 01/01/2016, but unfortunetely i just find difinitions not what to do pratically :(
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In Karnataka State ( HK Region) toor dal is major crops and peoples are consuming more for their daily food process. and This area of soil and ground water is contaminated with fluoride also. In this connection I wish to asses the fluoride contamination in toor daal.
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Dear Prakash,
A solid sample portion is wetted with a calcium oxide solution before being evaporated to dryness. The sample is calcined at 600 ° C and fused with sodium hydroxide. The ash is dissolved in water. The fluorides contained in the sample are separated from other constituents by distillation in an acidic medium. Fluoride is then simply measured by an electrode.
The measure can also be done by a colorimetric and complexometric method. The distillate is mixed with a solution of alizarin and lanthanum to form a blue complex whose absorbance at 620 nm is proportional to the concentration of fluorides. The simplest method is obviously the first one.
With my best regards
Prof. Bachir ACHOUR
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i wish to know how can i calculate my yeast accumulation.
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I would suggest the following this solution as I have done it before and it works well.
You formulate a general mass balance in the reactor with both inlets and outlets. Said mass balance will feature the terms of inlet and outlet streams, accumulation and reaction rate of all the species in the fermentation. In fact, you should take into account two inlets, one for the reactants and one just for the strain.
Outlet  - Inlet + Accumulation = Generation
For the fermentation of glucose into ethanol with Saccharomyces cerevisiae (the yeast), for example, you may have the following balances:
Glucose
(Fout * Woutglucose) - (Fin * Winglucose) + d/dt(Mglucose) = rglucose * Volume
Cells
(Fout * Woutcells) - (Fin * Wincells)  + (Fincells_inoculum ) + d/dt(Mgcells) = rcells * Volume
 Ethanol
(Fout * Woutethanol) - (Fin * Winethanol) + d/dt(Methanol) = rethanol * Volume
You can operate this as fed-batch by opening an closing the inlets and outlet streams, for fill-up and empty. The kinetic models can be found in the following works. Please do not hesitate to contact me if you require additional information
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Does anyone know of any mass spectral libraries similar to the Wiley Registry/NIST, but with high resolution data? Or a web-based database (such as Chemspider), but with GC-HRMS (EI) data?
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Mass Bank has GC-EI-TOF entries
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I am doing analysis of PM10 collected on Quartz fiber filter.I am expecting organic compounds like n-alkanoic acids decanoic acid, dodecanoic acid etc...I have only one standard that is Heptadecanoic acid.Could i use this chemical for quantify all the acids by making calibration curve from this standard.
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Hi Sarika,
I dont think so. I analysed monocarboxylic acids (C8 - C20) by GC-MS 5 years ago. I derivatized them into methyl esters by BF3/methanol and the peak area was different for different acids. The peak area of C16 was the biggest. However I dont have experiences with HPLC.
Rastislav.... PM10 means particles less than 10 micrometers. PM is Particulate Matter.
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I am working on simple aromatic hydrocarbon molecules found in aquatic animals. I am very new to NMR. I have NMR spectra of several compound but i dont know how to determine their structure. Can you please give me any online/offline tool/software where i need to put the sprectra and the calculate the structure for me.
Thank you in advance
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Please send a picture of your NMR spectra  as jpg or pdf.
Please give infos about the solvent used for NMR samples and , very important, are your samples of aromatic hydrocarbons   PURE??
If not , you 'll obtain the NMR- spectrum of a mixture. On other part , you need an elemental analysis of your A.H.  and a standard of your A.H. Why a standard?
If you give microL (liquid or mg if solid )of your A.H. standard in your NMR tube , you can see the increase of  the related peaks in your NMR spectrum if you have a mixture.
Define the isolation of your A.H. (organs ....) when you write :
I am working on simple aromatic hydrocarbon molecules found in aquatic animals.
What a kind (s) of animals?
For your question Nr. 2:
 you please give me any online/offline tool/software where i need to put the sprectra and the calculate the structure for me.
please read this link :
you can give in Google :  NMR prediction on line . and you 'll obtain a lot of free NMRsoftware too.
Thank you in advance for the NMR files.
JRG
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I need a refernce to an accurate method for the gravimetiric determination of the concentration  of suspended particulate matter in deep ocean waters.
The method should be widely and currently used in deep sea research
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we are analysing various ganoderic acids in Ganoderma Mushroom. What is the best labelled standard that i can use to calculate the recovery and EE of my method.
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Instead of a labelled compound use Hydrocortisone as a standard; this method was validated by Yongli Liu, Youping Liu, Feng Qiu, Xin Di, "Sensitive and selective liquid chromatography–tandem mass spectrometry method for the determination of five ganoderic acids in Ganoderma lucidum and its related species" Journal of Pharmaceutical and Biomedical Analysis 54 (2011) 717–721.
I couldn't locate a source for any heavy isotope labeled Ganoderic Acids through Scifinder or Chemexper. The best internal standard would be a heavy isotope labeled version of each Ganoderic Acid, the ones to purchase (or synthesize) are the lowest priced ones available that will work for your application.
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Heavy metals in air
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Hi Yusef,
The GEOS-Chem model can be used for your purpose. Please refer to the web site 'http://acmg.seas.harvard.edu/geos/'. Hope this helps.
Regards,
Dr. Rong-Ming Hu
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My government have plan to build quarantine island, we must justification of quarantine island is very important.
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There are also LC-MS methods by Blackwell et al. 
Liquid chromatography-tandem mass spectrometry analysis of 17α-trenbolone, 17β-trenbolone and trendione in airborne particulate matter.  Blackwell BR, Cai Q, Smith PN, Cobb GP.  Talanta. 2011 Sep 15;85(3):1317-23. doi: 10.1016/j.talanta.2011.06.011.
This one is located on Research gate.
Unless they have recently changed policy, US Geological Survey methods require GC-MS of derivitized Trenbolone due to keto-enol tautomerizm alterations of deuterated internal standards.   So if you go the LC-MS route, be careful what solvents you use for sample processing.
Finally there are immunoassay kits for trenbolone that are relatively sensitive.  I do not have those actual references, but you can evaluate the literature from Bradley Johnson.
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going to follow batch extraction test using EDTA to specify the best condition of pH,conc of extractant,agitation speed,contact time for identifying the effective removal of heavy metals from my sample..supernatant is further analysed by ICP.To anlaysing into ICP,is it necessary to change the supernatant into acid nature?(acid digestion method)  or colourless(supernatant)....
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Dear Karthika
In this case it is important that standards and samples are matched as closely as possible. Although the high temperature of the plasma overcomes most chemical interferences that could potentially occur in the atom cell it has a nebulizer and mixing chamber and this sample transport interference  will be as much an issue as it would be in AAS.  Any solutes that can affect the  size distribution of droplets from the nebulizer can potentially interfere. This could include EDTA so put it in the standards. If standards need to be acidified you also need to put the same amount of acid in the samples.
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We have prepared plastic with As+3 compound. We applied 250 C temperature and pressure during the processing samples. After preparation of sample As state has been changed to +5. Please let me how it was changed. We have mixed other inorganic compounds also such Fe, Pb, Cr etc. 
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I agree with Ma Jie, In fact, even for As concentration in the plant samples, most of the time we use below than 80C for measuring DW of the biomass. Because above 80-90C, it increases As evaporation from the samples. So, i think high temperature is the main factor here.
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I am working on microbial dye degradation. I have the data for absorption maxima for a particular dye.During my studies I found some of the dyes undergo first fungal biosorption then undergoes degradation or decolorization. The degradation may be complete or incomplete.How to check the decolorization efficiency ? Because culture filtrate contains no dye.
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Dear Venkata,
I had worked on bioremediation (microbial). To see biosorption, I used to dissolve microbial pellet and check its absorbance while the supernatant was used to check biodecolorization. But I am not sure about fungal cultures.
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The needle of the SPME is bent during extraction (agitation) and it breaks. It happens every 6 or 7 samples. Can anybody give me an advice?
I had reviewed several times the alignment of holder, needle, etc.
For more information I am using the MassHunter for controlling the CTC sampler. My method requieres direct immersion and agitation.
Thank you very much
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Hi Juan, 
if you are sure about your alignment parameters and your tension cords are in a good status, then maybe your problem is the septa of your vial. I had a similar issue before. I could not understand why my SPME outer needle would bend, while the alignment and all the autosampler hardware was okay.  Finally I figured out that the septa of my vials were slightly thicker that the ones I had used before (it was due to a factory problem). Another parameter you may want to check it is your needle penetration speed.
I hope this can help 
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Even if I understand that some heavy metals such as Cd are more mobile than Pb, as an instance, I am still not sure why the Casparian Strip does not work avoiding the uptake of Cd, and whereas, this heavy metal can be translocated to the fruits and grains of plants. I mean, if the Casparian Strip really works, it means avoidance of entrance of all heavy metals, or is there any relationship with the valency of the chemistry of the particular metal? Thanks in advance
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The Casparian strip only prevents ions to reach the stele and therefore the xylem and the further translocation aboveground. Uptake of heavy metals means internalization into the symplast or root cells, which occurs all along the way of ions into the apoplast till the capsarian strip, particularly at epidermis. The internalization from the apoplast into the symplast is mediated by transporters that are more or less specific of ions. Cadmium is internalized by transporters mediating the internalization of Zn, Fe, Ca. See the following references for more details :
Lux, A., Martinka, M., Vaculík, M., White, P.J., 2011. Root Responses to Cadmium in the Rhizosphere: A Review. Journal of Experimental Botany 62, 21–37. doi:10.1093/jxb/erq281
Laporte, M.A., Denaix, L., Pagès, L., Sterckeman, T., Flénet, F., Dauguet, S., Nguyen, C., 2013. Longitudinal variation in cadmium influx in intact first order lateral roots of sunflower (Helianthus annuus. L). Plant and Soil 372, 581–595. doi:10.1007/s11104-013-1756-3
Laporte, M.A., Denaix, L., Dauguet, S., Nguyen, C., 2014. Longitudinal variation in cadmium influx in sunflower (Helianthus annuus L.) roots as depending on the growth substrate, root age and root order. Plant and Soil 381, 235–247. doi:10.1007/s11104-014-2123-8
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It is a known fact that there is not one "plant availability". Availability of metals and metaloids depends on many parameters of the soils (pH, EC, CEC etc.) as well as on plant physiology (rhizosphere processses). Until today a lot of methods have been developed (column elution methods, single step extraction, sequential extraction), however if one is interested in the availability of non essential trace elements for plant growth (e.g. lanthanides, uranium) what method is the best? Does anybody have experience in that?  
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The only real way to measure plant availability is to be specific and measure update by the target plant of interest in the soil type that it needs to grow in(or that you want to grow it in). All other methods are just approximations and to have most confidence in any extraction methods they need to be calibrated against targeted pot trials.
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Especially for simultaneous determination of different antibiotic classes and the most suitable analytical instrument.
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Dear Norfaradila,
The best analytical method fpr the determination of antibacterial agents' concentration in wastewater is LC-MS, the second choice is HPLC. LC-MS is superior since MW of the antibacterial can be identified.
The following publications are examples of analytical methods used for the determination of some antibiotics concentration in wastewater:
1-Determination of Sulfonamide Antibiotics inWastewater by Liquid chromatography–
Tandem Mass Spectrometry
Eleni Botitsi, Charalampia Frosyni, and Despina Tsipi; General Chemical State Laboratory, Athens, Greece
2-Water Air Soil Pollut
DOI 10.1007/s11270-011-1049-5
Development Method for Extracting and Analyzing
Antibiotic and Hormone Residues from Treated Wastewater
Sludge and Composted Biosolids
Michelle Shafrir & Dror Avisar
Abstract Extraction and analysis methods have been developed for the detection of the following four antibacterial agents and two natural estrogens in treated  municipal wastewater sludge and commercial compost: sulfamethoxazole (SMX), sulfadimethoxine (SDM), tetracycline (TET), oxytetracycline (OXY), estrone (E1),
and 17β-estradiol (E2). The antibiotics and estrogens were extracted from secondary sludge and mixed compost using ultrasonic solvent extraction. Citric acid
(pH 4.7) and methanol were used as extraction buffer, followed by tandem-solid-phase extraction cleanup, strong anion exchange+hydrophilic–lipophilic balance
for antibiotics and CarboPrep/NAX for estrogens. For quantification, two different methods were employed, using HPLC–MS/MS, with an electrospray ionization
source for antibiotics and an atmospheric-pressure chemical ionization source for estrogens. Recoveries were 11–31% for the sulfonamides (SMX and SDM)
and tetracyclines (TET and OXY) and 30–59% for the estrogens (E1 and E2) over the entire method. Limits of detection for the extraction method were in the
nanogram per gram range for dry weight sludge and compost samples. Neither of the two sulfonamide antibiotics was detected in secondary sludge or mixed compost samples. Estrogens were found in compost in amounts of 160±65 ng/g (E1) and 21±3 ng/g (E2), but not in sludge. The tetracyclines, as well as what is
believed to be the 4-epimer of OXY, were found in both sludge and compost in amounts of 1.57±0.67 and 2.95±0.42 μg/g (TET), 0.56±0.12 and 6.51±0.52 μg/g
(OXY), and 7.60±1.68 and 1.35±0.24 μg/g (4-epiOXY), respectively. These results indicate that sorption-prone compounds are not removed during the wastewater treatment process and can persist through sludge digestion and that the composting process does not sufficiently eliminate these particular contaminants.
Thus, biosolids (even composted) are an additional source of drug residues leaching into the environment, and it must be considered while using biosolids as
fertilizer.
To view the full paper, please see attached file.
3-Liquid ChromatographyFast screening procedure for antibiotics in wastewaters by direct HPLC-DAD analysis
Authors
Salomé Teixeira,
 
Cristina Delerue-Matos,
 
Arminda Alves,
 
Lúcia Santos
 
First published: 10 September 2008Full publication history
DOI: 10.1002/jssc.200800229View/save citation
Cited by: 15 articlesRefreshcitation countCiting literature
 
Abstract
Growing concern about the contamination of wastewaters by antibiotics demands fast but sensitive analytical methodologies, for the screening of a large number of samples. The purpose of this work was to develop a simple methodology, using direct injection of the samples, by HPLC with diode array detection (DAD), for a multiresidue analysis of five antibiotics of different classes. Wastewater from an urban water treatment plant was selected as a model to study possible coelution of interfering compounds. The linearity interval ranged from 40 to 400 μg/L for amoxicillin (Amox), metronidazole (Metro), cefazolin (Cefa), and chloramphenicol (Chloram) and from 20 to 200 μg/L for sulfamethoxazole (Sulfa), with LODs lower than 14 μg/L. Repeatability, expressed by the CV of six repeated injections, ranged from 1 to 8%, while the intermediate precision varied between 2 and 11%. The recovery ranged from 90 to 109%. This method enables the fast screening of a large number of samples, with an expanded uncertainty in the 1–22% range. The advantage of the proposed method is to significantly reduce the number of samples to be analyzed by more complex methods.
To view the full paper, please use the following link:
4- J Chromatogr B Analyt Technol Biomed Life Sci. 2014 Oct 15;969:162-70. doi: 10.1016/j.jchromb.2014.08.008. Epub 2014 Aug 12.
Simultaneous determination of most prescribed antibiotics in multiple urban wastewater by SPE-LC-MS/MS.
Rossmann J1, Schubert S2, Gurke R3, Oertel R2, Kirch W3.
Author information
 
Abstract
A rapid analytical method was developed for the application of a long-term monitoring (>one year) of the most prescribed and often in hospitals used antibiotics in diverse wastewaters of an urban sewage treatment plant (STP). Additionally to the selected multi-class antibiotics amoxicillin, penicillin V and piperacillin (penicillins), cefotaxime and cefuroxime (cephalosporins), azithromycin, clarithromycin and roxithromycin (macrolids), ciprofloxacin and levofloxacin-ofloxacin (fluoroquinolones), clindamycin (lincosamide), doxycycline (tetracycline), sulfamethoxazole (sulfonamide) and trimethoprim (dihydrofolate reductase inhibitor), the bioactive metabolite clindamycin-sulfoxide, the reserve antibiotic vancomycin (glycopeptide) and as tracer of the STP the anticonvulsant carbamazepine and the antifungal fluconazole were involved. The analytical method combines a low-sample-volume solid phase extraction (SPE), followed by a chromatographic separation using a reversed phase (RP) and hydrophilic interaction liquid chromatography (HILIC) technique, respectively, coupled to a triple quadrupole mass spectrometer. Detection was performed with multiple reaction monitoring (MRM) measured with positive electrospray ionization (ESI+). The extraction efficiency of different SPE cartridges and optimized pH-values of the preparation procedure were tested. Finally, the extraction of antibiotics was realized with the Oasis HLB cartridge and a pH adjustment at 3.5. An external calibration curve in diluted blank urine was used for quality control of the sample set of daily composite samples of the STP for the duration of one year monitoring. The squared coefficient of determination (r(2)) in the concentration range (20-20,000ng/L or 100-100,000ng/L) of the calibration curves for the method was higher than 0.99 for all determined substances. The limit of quantification (LoQ) ranged between 0.8ng/L (azithromycin) and 245.1ng/L (vancomycin). Furthermore, a standard addition was used for quantification in wastewater samples. The process efficiencies ranged from 20% (doxycycline) to 134% (cefuroxime) in influent samples and from 31% (doxycycline) to 171% (cefuroxime) in effluent samples of the STP. All selected substances have been found in wastewater samples. Cefuroxime, doxycycline, levofloxacin, piperacillin, sulfamethoxazole and carbamazepine showed highest concentrations up to 6.2μg/L.
5- Concentrations of Selected Pharmaceuticals and Antibiotics in South-Central Pennsylvania Waters, March through September 2006
U.S. Geological Survey Data Series 300
By Connie A. Loper, J.Kent Crawford, Kim L. Otto, Rhonda L. Manning, Michael T. Meyer, and Edward T. Furlong
This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.
View the full report in PDF 5.59 MB
Download Microsoft Office Excel Worksheet--Table 6 ZIP 75 KB
Abstract
This report presents environmental and quality-control data from analyses of 15 pharmaceutical and 31 antibiotic compounds in water samples from streams and wells in south-central Pennsylvania. The analyses are part of a study by the U.S. Geological Survey (USGS) in cooperation with the Pennsylvania Department of Environmental Protection (PADEP) to define concentrations of selected emerging contaminants in streams and well water in Pennsylvania. Sampling was conducted at 11 stream sites and at 6 wells in 9 counties of south-central Pennsylvania. Five of the streams received municipal wastewater and 6 of the streams received runoff from agricultural areas dominated by animal-feeding operations. For all 11 streams, samples were collected at locations upstream and downstream of the municipal effluents or animal-feeding operations. All six wells were in agricultural settings.
A total of 120 environmental samples and 21 quality-control samples were analyzed for the study. Samples were collected at each site in March/April, May, July, and September 2006 to obtain information on changes in concentration that could be related to seasonal use of compounds.
For streams, 13 pharmaceuticals and 11 antibiotics were detected at least 1 time. Detections included analytical results that were estimated or above the minimum reporting limits. Seventy-eight percent of all detections were analyzed in samples collected downstream from municipal-wastewater effluents. For streams receiving wastewater effluents, the pharmaceuticals caffeine and para-xanthine (a degradation product of caffeine) had the greatest concentrations, 4.75 μg/L (micrograms per liter) and 0.853 μg/L, respectively. Other pharmaceuticals and their respective maximum concentrations were carbamazepine (0.516 μg/L) and ibuprofen (0.277 μg/L). For streams receiving wastewater effluents, the antibiotic azithromycin had the greatest concentration (1.65 μg/L), followed by sulfamethoxazole (1.34 μg/L), ofloxacin (0.329 μg/L), and trimethoprim (0.256 μg/L).
For streams receiving runoff from animal-feeding operations, the only pharmaceuticals detected were acetaminophen, caffeine, cotinine, diphenhydramine, and carbamazepine. The maximum concentration for pharmaceuticals was 0.053 μg/L. Three streams receiving runoff from animal-feeding operations had detections of one or more antibiotic compound--oxytetracycline, sulfadimethoxine, sulfamethoxazole, and tylosin. The maximum concentration for antibiotics was 0.157 μg/L. The average number of compounds (pharmaceuticals and antibiotics) detected in sites downstream from animal-feeding operations was three. The average number of compounds detected downstream from municipal-wastewater effluents was 13.
For wells used to supply livestock, four compounds were detected--two pharmaceuticals (cotinine and diphenhydramine) and two antibiotics (tylosin and sulfamethoxazole). There were five detections in all the well samples. The maximum concentration detected in well water was for cotinine, estimated to be 0.024 μg/L.
Seasonal occurrence of pharmaceutical and antibiotic compounds in stream water varied by compound and site type. At four stream sites, the same compounds were detected in all four seasonal samples. At other sites, pharmaceutical or antibiotic compounds were detected only one time in seasonal samples. Winter samples collected in streams receiving municipalwastewater effluent had the greatest number of compounds detected (21).
Research analytical methods were used to determine concentrations for pharmaceuticals and antibiotics. To assist in evaluating the quality of the analyses, detailed information is presented on laboratory methodology and results from qualitycontrol samples. Quality-control data include results for nine blanks, nine duplicate environmental sample pairs, and three laboratory-spiked environmental samples as well as the recoveries of compounds in laboratory surrogates and laboratory reagent spikes.
6-Simultaneous determination of three classes of antibiotics in the suspended
solids of swine wastewater by ultrasonic extraction, solid-phase extraction and
liquid chromatography-mass spectrometry
Xun Pan, Zhimin Qiang∗
, Weiwei Ben, Meixue Chen
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. E-mail: qiangz@rcees.ac.cn
Received 24 November 2010; revised 21 January 2011; accepted 17 February 2011
Abstract
This work describes a systematic approach to the development of a method for simultaneous determination of three classes of veterinary antibiotics in the suspended solids (SS) of swine wastewater, including five sulfonamides, three tetracyclines and one macrolide (tiamulin). The entire procedures for sample pretreatment, ultrasonic extraction (USE), solid-phase extraction (SPE), and
liquid chromatography-mass spectrometry (LC-MS) quantification were examined and optimized. The recovery efficiencies were found to be 76%–104% for sulfonamides, 81%–112% for tetracyclines, and 51%–64% for tiamulin at three spiking levels. The intra-day and inter-day precisions, as expressed by the relative standard deviation (RSD), were below 17%. The method detection limits (MDLs) were between 0.14 and 7.14 µg/kg, depending on a specific antibiotic studied. The developed method was applied to field samples collected from three concentrated swine feeding plants located in Beijing, Shanghai and Shandong province of China. All the investigated antibiotics were detected in both SS and liquid phase of swine wastewater, with partition coefficients (logKd) ranging from 0.49 to 2.30.
This study demonstrates that the SS can not be ignored when determining the concentrations of antibiotics in swine wastewater
For full publication, please see attached file.
Hoping this will be helpful,
Rafik
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I found this interesting paper that reports the relative water content (RWC) in the leaves of 13 woody species (between 77 and 91% of water).
But what about the rest of the tree. Of course I am not expecting an absolute answer as this would vary with species, age, season, health etc. But is there any study that has measured water content in whole trees? 
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Thanks Tim, 
This paper does look interesting, I will see if I can find more on their website. Thanks also for explaining the turgor loss point, makes more sense to me now.
Cheers,
Stephane.
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Our large old distilled water still uses building steam from a 10 megawatt power plant.  The still designer says the condensed water from the steam, which is used as feedwater, can't have more than 2 ppm of aliphatic hydrocarbons.  Anti-corrosion and foaming additives for the boiler feedwater are the contributions to this.  What's the best way to measure the steam condensate for this?  It is cooled through a heat exchanger and used for the feedwater.
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Sounds like you will need to do an extractable petroleum hydrocarbon (EPH) analysis.  Many different ways to do this, each US State pretty much has their own method for this and it's done primarily to test for leaky underground storage tanks for gasoline or diesel.  I've attached a link to one method for you.  It gives detection limits below what your still manufacturer requires.  Any good commercial environmental lab will offer this analysis as part of their services. The attached will have all the information you require.
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dust roads has significant concentrations of heavy metals, you can be given some use?
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Do you want to take samples  for analysis or use the dust as a source for reusing the (heavy) metals?
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Dear researchers;
## Can anybody give me geochemical background concentration values of the elements in the Earth’s crust (crustal average).
###  Also, I need a values of elements  trace in :
"Clarke values" n chemical composition of the upper continental crust ( UCC) ( Taylor and McLennan, 1995).
Geochemical background concentration of the heavy metal (crustal average) (Taylor and McLennan, 1985)
I need for these Some papers :
[1] K. K. Turekian and K. H. Wedepohl, “Distribution of the elements in some major units of the earth’s crust,” Geological Society of America Bulletin, vol. 72, no. 2, pp. 175–192, 1961.
[2] D. R. Lide, CRC Handbook of Chemistry and Physics,Geophysics,Astronomy, and Acoustics, Abundance of Elements in the Earth’s Crust and in the Sea, section 14, CRC Press, Boca Raton, Fla,USA, 2005.
Thank you
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You can look at the article by Taylor and McLenan (1995). DOI 10,1029/95RG00262.
The Geochemical evolution of the continental crust in Reviews of Geophysics, 33, 241-265.
 N.J.Pawar
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I´m working with insect d13C and d15N isotopes and we all know that insects are composed of a good percentage of chitin. I would be interested in knowing only carbon and nitrogen isotopes excluding the chitin contribution (since I processed the whole insect for another purpose). Does anybody know a correction factor available for chitin in insects? Or correction factors for similar material (cellulose, keratin???).
Thanks
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Rafik actually I was thinking about those two manuscripts what do you think?
1 - Schimmelmann, A., and DeNiro, M.J., 1986a, Stable isotopic studies on
chitin, measurements on chitin/chitosan isolates and d-glucosamine
hydrochloride from chitin, in Muzzarelli, R., Jeuniauz, C., and
Gooday, G., eds., Chitin in nature and technology, New York,
Plenum, p. 357–364.
2 - Schimmelmann, A., and DeNiro, M.J., 1986b, Stable isotopic studies on
chitin. II: The 13C/12C and 15N/14N ratios in arthropod chitin:
Contributions in Marine Science, v. 29, p. 113–130.
That would be great, I don´t know how to thank you
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for wastewater analysis If I want to determine sulfate, sulfide, thiosulfate, and sulfite in one solution, can I use IC, or I have to use ICP? And any other method?
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Dear Ally,
You can use IC for the determination of the four species. Please see attached publications.
Hoping this will be helpful,
Rafik
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The typical WWTP effluent release standards for bacterial indicators do not include any information on levels of antibiotic resistant microbial levels or the potential for transfer, via genes, to environmental reservoirs. Additionally, the level of impacted bacteria in the viable but non-culturable state will confound these lab results and thus throw false negatives. As a consequence, what is actually being discharged remains an unknown and hence potentially severe long-term adverse public health risk
Dr Edo McGowan, former USAID Regional Environmental Officer covering Eastern and Southern Africa.
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I think all people agree that hospital do emit antibiotic resistent bacteria ... I can find some references if you cannot
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nBTPT and heavy metal Cu and Zn inhibits soil urease activity and thereby reduces urea hydrolysis.
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When you apply urea to the soil as source of nitrogen fertilizer, it will hydrolyze into ammonia very fast. Ammonia is a gas under normal temperature and pressure condition. The loss of this gas into the atmosphere is economically substantial. This hydrolysis process is facilitated by the enzyme urease. So, urease inhibition is the process of slowing down this hydrolysis process to minimize N loss. The mechanism is that those chemicals considered as urease inhibitors will bind the enzyme urease thus slowing down its effect in urease hydrolysis. In addition, I encourage you to read the following recent publication. Agron. J. Accepted Paper, posted 11/10/2015. doi:10.2134/agronj2015.0391
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I did a sedimentary rock sample digestion of only 2g(required mass to test for presence of component) as prescribed by USEPA 3050B method on hot plate and tested for heavy metal presence after making up to 100ml. I now want to digest as large as 2kg(2000g) of the rock which will give about 100Litres of solution(by making up 100ml in 2g) for use as influent in column adsorption experiment to adsorb out the heavy metal. Can someone assist with minimum rock mass (e.g. 4g, 10g, 50g, etc.) to digest that still maintains good digestion process to achieve the 2kg sample?
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Thanks Mr. Asif Saleh Qureshi
I always pulverise before such digestion. I'm digesting as much as 2kg to obtain about 100 Litres of digested solution to be used for an experiment which small sample of say 1g(used to test for presence which I have done earlier) can't provide this required volume if to maintain the same concentration. so 100 L requires about 2kg sample to have required concentration according USEPA method 3050B Thx sir
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I am trying to identify which rock type can be attributed in some results from XRF analysis concerning major and trace elements data. I trying to find one but it is quite difficult. I thought an online comparison should exist out there in the internet space.... And I need also the confidence level or all possibilities.  Could you help? Thanks in advance!
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I would recommend looking at the hand specimen of your rock, then perhaps making a thin section and only then start doing chemical analysis. The best free software to use is your brain ;-)
On a more helpful note: are you dealing with igneous, metamorphic or sedimentary rocks, or is that something that you do not know either? A weathered granite and an feldspathic arkose could give rather similar XRF results, but would deserve different names...
If you want examples of the chemical composition of igneous rocks, you can try http://georoc.mpch-mainz.gwdg.de/georoc/
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In my research study, i am focusing into the treatment of organic compounds in rainwater using photocatalysis. the organic compounds involved in my study are Naphthalene, Fluoranthene, Pyrene, Lindane & DDT. In order to dissolve their powdered standard for preparing synthetic rainwater, I have been using an organic solvent, which is chloroform. Is there any further reactions that I should take note (since every compound will be degraded eventually) ? Which organic solvent (Eg: methyl chloride, methanol, choloroform, ethyl acetate, ethanol, etc.) that is suitable the most in dissolving the organic compounds i mentioned earlier?
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Solubility of organic compounds is purely depends on its polarity. For less polar compounds, we have to use less polar solvent. For example: n-Hexane is suitable for Naphthalene, Fluoranthene, Pyrene and Lindane. We can use Chloroform, dichloromethane, ethylacetate, acetone, acetonitrile and carbon disulfide for DDT  
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I use the Rancimat to determine the shelf life of some edible oils, I need to know:
The minimum and the maximum limits of low-molecular weight of volatile organic compounds? and How the device converts the conductivity of water to the indicators of oxidative damage?
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The Rancimat method is an accelerated aging test. Air is passing through the sample in the reaction vessel at constant elevated temperature. In this process fatty acids are oxidized. At the end of the test volatile, secondary reaction products are formed, which are transported into the measuring vessel by the air stream and absorbed in the measuring solution (deionized water). The continuously recorded electrical conductivity of the measuring solution is increasing due to the absorption of the reaction products. Thus their appearance can be detected. The time until secondary reaction products are detected is called induction time. It characterizes the oxidation stability of oils and fats.
The measuring temperature depends on the oxidation stability of the sample. For the sample types described in this document, usually temperatures between 80 and 160 °C are appropriate. 50 to 220 °C are possible. Most tests are carried out at 120 °C (Iower stability – lower temperature). The rule of thumb is: a temperature increase of 10 °C lowers the induction time by a factor of two.
Also, you can check in this pdf, about correlation between molecular weight (MW, g/mol) of saturated fatty acid alkyl esters and oxidation time. A correlation was noticed in which the oxidation onset temperature (OT) of saturated fatty esters increased with decreasing molecular weight (R2 0.7328).
I think this machine able to measure all kinds of oils even Biodiesel, so you not need it to know the minim or maximum molecular weight of volatile compounds.  
Good luck my brother Dr. Marwan. :)
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When it come to batch dissolution experiment (for water-rock interaction study), most authors have selected igneous rocks, sedimentary rocks and minerals formed under igneous conditions. Is there any special reason for that? Is there any article for the same experiment where metamorphic rocks were used?
Thank you
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There may be no specific reason why igneous rocks were used and metamorphic rocks were not used, and it may be that the application of the research was for an area with igneous rocks (without metamorphic rocks). I do not believe there are any specific water-rock interaction differences between igneous and metamorphic rocks. A metamorphic rock is a type of rock which has been changed by extreme heat and pressure. So, an igneous rock can become metamorphic by exposing it to heat and pressure. This heat and pressure typically dissolves and re-precipitates some of the minerals in the rock. So, there are some differences in types and chemistry of the minerals, and the morphology of the minerals may be different, which may impact dissolution. Hope that helps.
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The Hach Lange kit goes from 0-1000mg/L.
Hach Lange say their LOD is around 6ppm and the LOQ is 21ppm.
Does anyone know how they will determine the LOD and LOQ for these kits?
I understand that one would determine 3xstd(blank) to get the LOD, however because these are test vials, you need to blank initially with the blank you made. Would I then just read the blank after blanking with it?
A problem with these vials is that if I do blank with the blank and read it back it gives me zero as it should. But when you move the test vial slightly in the spec, the values no longer reads zero. this is because the glass vial is not optically the same at all points (and it is round which cause light scattering). I cant just keep moving the vial around and taking any reading I want.
Thank you very much.
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If your blanks read zero you need to determine the standard deviation of repeated analysis of a low concentration standard. I would prepare a standard with a COD around 20 mg/L and determine seven replicates of this.
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what are the procedure(s) or techniques used for analyzing the components of wastewater especially antibiotics and organic compounds?
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Check out these publications links  from DC Water and World Health Organization (WHO) which can give you a start on what to anticipate and test methods, the first link and last one has a table listing potential pharmaceuticals and tests:
Also check out the USEPA website.
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How can I modify shrimp shell for hexavalent chromium (Cr VI) removal? Thanks
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Thank Supriya Singh, Ayawei N and Caitlin Eger very much!