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I want to estimate freezing point of a mixture made from Ehhanol (H₃CCH₂OH, MW: 46.07 g/mol) , mono propylene glycol (CH₃CH(OH)CH₂OH, MW: 76.1 g/mol) and water. And the ratio of the mixure will vary for example I can start with 1:1:1 and so on. I spent couple of week to google it but not able to figure out how to do that. If someone here have some experience with it or have some suggestion / literature then please help to solve for this problem.
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As that is a calculation of colligative properties of non-electrolytes it may be a matter of deciding which is the "solvent" and which are the solutes. As the freezing point depression ('C/mole solute) is known for each of them, a comparison (or convergence) of the calculated freezing point for any given mixture could be made.
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I am trying to obtain chitin by a chemical method. After deproteinization and demineralization processes, the powder obtained after each step is too alkaline or acidic respectively. Then, I spend a lot of deionized water during washing power. Is it acceptable to add something to the deionized water to get neutrality faster?
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Think Rasweefli has developed a better process than Khalifa Al Shaqsi
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I know magnetic separation can separate Fe, γ-Fe2O3, Fe3O4. But I don't know how to get Fe powders from residues. Someone say sodium pyrophosphate could remove γ-Fe2O3, Fe3O4, is it a feasible method ? Or other better method?
Thanks very much for your answers!
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Hi you should dissolve your target iron oxides, though the possibility exists that your elemental iron could also be attacked.
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Excessive use of chemicals in agriculture results in contamination of products with high levels of chemical residues.
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The numerous negative health effects that have been associated with chemical pesticides include, among other effects, dermatological, gastrointestinal, neurological, carcinogenic, respiratory, reproductive, and endocrine effects. Chemical fertilizer overuse can contribute to soil acidification and soil crust, thereby reducing the content of organic matter, humus content, beneficial species, stunting plant growth, altering the pH of the soil, growing pests, and even leading to the release of greenhouse gases. Farmers in developing countries are experiencing, either short-term or long-term, health effects from exposures to agricultural chemicals, including severe symptoms (e.g. headaches, skin rashes, eye irritations) and some chronic effects (e.g. cancer, endocrine disruption, birth defects).
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Dear Researchers :
I have this question and I have an hypothesis:
Why Natural HDPE, when extruded at temperatures about 100 °C (around) it has a white (but pale white), and then when the polymer cools down it color turns between white an yellow.
I understand that this phenomenon it is a general case of all LLDPE, LDPE and HDPE , and in all fabrication processes : Extrusion, injection, molding, pressing, etc.
So this is fundamentally, a chemical characteristic of the material ...
It has to do with a change in the Oxygen concentration in the material ?
Thank you all in advance,
Best Regards !
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Dear Franklin Uriel Parás Hernández, both degradation and crystallization are behind the change in color aspect. My Regards
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I have been trying to detect a compound using a GC-MS system, but the probability is not high enough thanks to a lot of other compounds with similar mass spectra in NIST library. The only way I can think of to distinguish among them is retention index since some of those compounds are hard to obtain. I noticed that temperature programmed retention indices are not really system independent.
Therefore, under what conditions beside same stationary phases (DB-5MS in my case) can I make a comparison? Should the temperature programs and column lengths strictly match?
Thanks in advance for any advice.
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The database of compounds in Retention Index (RI) are linked to the columnn phase.
The brand of your column may change the RI a little bit from one to another. So for more precision of the identifcation, it's important to have the same column brand as the one used to build the database of compounds in RI.
Sometimes, the RI may change a bit as well depending on the injected products chemistry in this column.
But the indices are not linked to the temperature programs since you have to use the same method for the analysed chromatogram (e.g. sample) and your chromatogram of indices reference (alkanes, Ethyl Ester etc.). The retention time will move the same way on both chromatogram allowing to convert from RT to RI correctly whatever the temperature program and the column size (but obviously the shorter the harder the compounds identification because of the coelutions, but still can be identified with the database of compounds in RI...).
WARNING: the temperature program has to be linear during the elution of all compounds (you can have a step at the beginning and at the end).
To improve the identification, the best configuration is to have two columns (e.g. polar, non polar) and to cross the results between the two database. This way even you are at +-20 around the RI of your compounds (needed if you have to deal with a different column brand comparing to the database you own or find online), only the common compound(s) will show up in the result of the crossing of the two lists (polar, non polar) from the two database.
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Q1: In many articles on jadeite and jadeitite(Shi 2008,CÁRDENAS-PÁRRAGA2021, Meng 2016, Abduriyim2017, et al.), scholars draw spider diagram based on trace element data and REE from LA-CIP-MS. But the number of elements in the horizontal coordinate is often different. What is the principle on which this is selected?
Q2: When some of the results of the test are below the detection limit(bdl) , or the corresponding elements are not detected (nd), how should they be reflected in the diagram?
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Trace element abundance plots (spidergrams) are used to illustrate the rare earth element or mantle incompatible trace element contents of a sample. The order of trace elements is usually shown in the order of decreasing ionic radii. In the case of the REE, where the lighter elements such as La have the larger ionic radii (due to the lanthanide contraction with higher atomic numbers), the LREE are shown on the left and the HREE on the right part of the spidergram. Elements concentrations below detection limit cannot be plotted. The computer program plotting the spidergram usually interpolates their values between its neighboring elements.
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Hello all,
I am preparing a compilation file for doing MESMER calculations but I am having an issue. I am running some g08 calculations with acetyl and it seems like the transition state from for going to the RO2 to QOOH is unstable as the difference between the target energy and the calculated energy differs by about 0.1 - 1.1. There is too big a difference in the energy barriers between the RO2 and QOOH, but all other energies for the stationary points in the channels are comparative to the expected value. The IRC from the obtained transition state gave a significantly high "jump" in the potential energy graph. Would anyone happen to know what is going on?
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By unstable, I mean that the SCF Done is coming out too low than the expected. The target energy is coming from a the Ethanal+OH/O2 system that has been studied in literature that we are trying to emulate. The unit of measurement is in Hartrees
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What is the approximate COD value of 50 ppm aqueous Acetaminophen solution (C8H9NO2, Mol wt 151.163 g/mol)?
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Aarif Shah, If the COD analysis is the standard one with chromate in acid I think the standard balanced reaction will be: C8H9NO2 + 9O2 +H+ -> 8CO2 + 4H2O + NH4+
The combusting reaction suggested by Kai Bester:
C8H9NO2 + 11O2 -> 8CO2 + 2½H2O + NO3- + H+ in my opinion overestimate the COD as typically chromic acid is not able to oxidize N(-III) in the standard analysishttps://en.wikipedia.org/wiki/Chemical_oxygen_demand.
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Nbc-Ni Cermets samples are sintered in a vacuum sintering furnace at @1450 degrees. The Samples were placed in the Alumina Piece as shown in the attached pictures. after sintering the color of the alumina piece changes to blue as shown in the picture. what can be the reason behind it? Thanks
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Dear Abdul,
I never worked with these materials but they are high melting point-based, so I believe the influence will be minor. I recommend you'll measure Al content prior to and after the heat treatment of your samples.
Good luck.
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chemical analysis
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Wang Yun Google is you friend. Properties are identical to zirconia with which it is intimately found. Wiki gives you:
"Hafnium(IV) oxide is quite inert. It reacts with strong acids such as concentrated sulfuric acid and with strong bases. It dissolves slowly in hydrofluoric acid to give fluorohafnate anions. At elevated temperatures, it reacts with chlorine in the presence of graphite or carbon tetrachloride to give hafnium tetrachloride"
It is separated from ZrO2 with difficulty.
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I prepared a solution of 100ml THF, 20ml tert-butoxide in THF and 4ml 1,3-propane sultone. To this, I added 11gm of my nanoparticles. Once I receive the result of ICP-AES, how should I calculate the number of particles present? How should I check whether I have achieved proper functionalization of my sample or not?
I have sent 1gm of sample powder for analysis.
Any suggestions will be much appreciated.
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You should take the density for this material, calculate the amount of the material in one spherical particle, calculate the mass of a particle. After the calculation of the desired concentration, you should take it as a total mass for this component. Take this mass and devide it by the mass of a particle. This will be a very-very rough estimation, but I cannot offer more acording to these conditions.
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Rare-earth halide/Rare-earth oxyhalide + alkali metal oxide = ?
For example, GdX3 + Li2O = ? at high temperature (~1300 C)
Please provide reference on your answer.
Thanks in advance
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For this type of question I would first get an idea of what could be expected by looking up the free energy of formation of the compounds in question at room temperature, in the humble Handbook of Chemistry and Physics or Lange's Handbook of Chemistry. Write a balanced equation and sum up the free energies of formation with the right algebraic signs. You'll find out that Li has a huge preference for the halide compounds compared to the lanthanides - tens of Kcal/mol per mole of bonds (M-X or M-O-).
Now for the 1300C part: I don't have this reference available with me, but it's likely that you can find you need for at least some of the compounds in
I. Barin, O. Knacke: Thermochemical Properties of Inorganic Substances. Springer-Verlag, Berlin — Verlag Stahleisen, Düsseldorf 1973 (and supplements published since).
Another good source for high temperatures is JANAF's Thermochemical Tables, but that is more restricted in terms of the compounds included, and I think it doesn't have what you need.
Chances are you'll find that the direction of these particular reactions at 1300C is the same as at room temperature. As long as only condensed phases are involved (solids and liquids), the change in molar heat capacity with temperature doesn't vary enough between the different compounds involved to lead to a sign reversal in the free energy of reaction. If the free energy of reaction at room temperature were, say, an order of magnitude smaller it would be much more difficult for me to make a prediction and I would need the actual 1300C data.
Finally, do not get discouraged if you find free energy of formation data just for a couple of trivalent lanthanides. The trend will be similar for the others, with the caveat that the degree of preference for bonding to oxide over halide tends to grow as you advance from the lighter lanthanides (La, Nd) to the heavier ones. Yttrium, of course, is similar roughly to dysprosium and holmium, and being much more common you may find data for it.
Best regards,
Emanuel Cooper
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I was unable to perform the sampling and analysis for 40 surface water and 20 groundwater samples, so I hired an in-country consultant firm to do it. The results that they returned were difficult to interpret and had extremely high levels of iron and manganese. I spoke with a former professor and he expressed concern from his long career of working in SE Asia that the subcontractor/lab might not have filtered the samples. How can I know that the results are for the water and not the particulates?
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Dear Liz Kendall . Do the analysis of the same samples at different labs then compare the results. See which results are the same and exclude the results that are far way from the comparable results. Then you can judge which lab is trusted and which is not. Best wishes.
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I measured the particles size (<1000 nm) in aqueous solutions by DLS, but I found these particles can aggregate spontaneously, and it seems that smaller particles aggregate more.
I sincerely hope you can help me explain this phenomena.
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Dear all, Ostwald ripening may be behind such aggregation, this mostly happen when surface free energy in too high, i.e. fine nanoparticles with high specific surface area, so coarsening of nanoparticles is the mean by which size is increased and specific surface area is reduced. Small nanoparticles are more prone to aggregation because of their high surface free energy which for stability reason should be reduced, and for this purpose protective colloids techniques have been developped to prolonge stability time. My Regards
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We have now over 350 000 chemicals and mixtures of chemicals registered for production and use, and more are developed constantly. How can we speed up their assessment for safety, to erase the backlog of unexamined ones?
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Approaches for read-across can provide a practical alternative for safety assessment of compounds which have similar structures or result in the same major metabolites.
"Read-across exploits information on structurally related (similar) analogues to derive hypotheses about the activity of the new chemical and hence predict its toxicity without experimental testing."
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Hello, I have some doubts about DLS measuring the size of the nanoparticles.I hope to get answers from you.
I measure TiO2-NPs(60nm,commercialization ) in 0.01M PBS. But Instrument prompt “sample too polydisperse for cumulant analysis” and “sample too polydisperse for distribution analysis” .Correlation Functions show the picture as followed. Why does this happen and how to avoid it ?
All dispersions were filtered with 0.45um filter. Ultrasonic dispersionwas used.
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Another reason could be the ionic strength of your PBS solution which may generate "Debye screening effects". This essentially means that electrostatic stabilization of your particles is decreased, leading to agglomeration and the apparent polydispersity.
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Hi, could you recommend a software compatible with spectrophotometry from various brands?
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P.S: I wash the column with water and methanol when I open and close the HPLC system.
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I have modified the graphene surface with copper oxide nanoparticles. so, I need to know whether my modification is correct or not? so what kind of characterization technique do I need to follow? XRD, EDS, AFM, FTIR are accessible for me.
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Using the XRD method, you can determine which copper oxide (nanophase) you have on the surface is bivalent or monovalent.
Using the EDS method, you will determine the ratio of carbon and copper content in nanoparticles
With the FTIR method, you can determine how copper atoms and ions are distributed and with which functional group they are bonded on the surface.
By method AFM you can see how the surface layer on nanoparticles changes and can determine its thickness and change.
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What are the benefits and the disadvantages of those?
what industries use those item beside Textile and paints?
does it have any other uses beside as dispersing agent?
which one gives more water resistance in paint and why?
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A lot of generic questions including judgements. From my side I can contribute as follows. Neutralizing PAA with NH4+ seems to me akward. I could imagine that this leads to protonated PAA (without any charge anymore) and NH3. From physical-chemical point of few, the behavior of NaPAA seems to be a bit more predictable.
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Palmyrah fruit pulp has a bitter taste due to this saponin, so I have to remove the saponin with a cheaper method which can be applicable to the fruit industry.
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add naringinase enzyme
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Where can I find alagebrium I want to use it in my research ?
And astaxanthin also and is it expensive?
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Hello.
Take alagebrium for example, you can search it on google scholar (or others) and get some articles about it. I picked up one as below.
Am J Transl Res. 2019; 11(3): 1569–1580.; PMCID: PMC6456531
In this article, they mentioned that "......AGEs inhibitor ALT-711 (20 μg/mL; MedChemExpress, China) was added......". So you can turn to "MedChemExpress" to see if the price and distance are ideal or not. If not, turn to other papers.
It has to be mentioned that, you can go to https://scifinder.cas.org/scifinder. Using substance identifier will easily lead you to what you want, though I had not bought through this way.
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Try to do a research for making a physical or chemical reaction in CO2 to transform it to Carbon and Diamond. What is the possibility for that ?
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The question in itself talks about the exciting opportunities to drive the interest of the researchers. As of now, the available processes are complex and do require sophisticated infrastructure. A perfect catalyst may solve this issue.
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Why the DNA sample that recovered from urea polyacrylamide gel electrophoresis become iced/solid during the ethanol preparation ?
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The critical step is removing the acrylamide after elution. After cutting the gel slice do not led it drying, keep it in the elution buffer and cut it in small fragments without crushing.
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I would like to analyse monocarboxylic acids higher than C20 (at least up to C30), but I cannot find a company for buying them. I prefer a mixture of more acids in an organic solvent but it can be solid standards. Thank you.
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Hi Kamil,
You may make an inquiry at Alfa Chemistry, they offer kinds of good-quality chemicals.
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say, when we take a simple titration of any compound to induce some change and study the change what we can see the change if it is faster change in the optical parameter or change in absorption or energy change or when we do its electro chemical analysis the changed species will be faster response as its electron transfer, what will be faster ? or both the methodologies will be different in kinetics due to different technical aspects and parameters? optical corresponds to the technique spectrophotometric methods . and more elaboratively from which technique we can get better electron transfer kinetics or the accurate degree of minimal observable change.
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Optical changes are faster
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Different results were obtained from both
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There is no simple answer to this question. So you are dealing with a situation where the results of the analysis of the elemental composition of a specific cement sample obtained by different methods differ significantly. Why do you think the differences are significant? Do these results have assigned uncertainty values? And would you like to know which method is generally more accurate? Theoretically, classical methods are more accurate, because XRF techniques are calibrated and checked with reference materials, the certified values of which were established mainly by classical methods. In a case like yours, this can only be checked with additional analyzes performed by another analyst in a specialized laboratory.
ZJ
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Dear researchers,
I do not know how to use Origin software to draw a graph with very high (3000) and very low (100) numbers on the vertical axis. Could you please help me?
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Dear all,
Would you please help me to find out the best approach to calculate the potential heat recovery from exothermic reactions? Are there any good references to introduce me in order to enhance my knowledge over recovering heat from exothermic reactions. I will be very thankful for your helpful advice and recommendations.
Thanks in Advance for your kind considerations.
Yours faithfully,
Nashmin
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There are a number of methods for measuring the heat of an exothermic reaction. But in any case, not so simple equipment is needed. One option is to use a bomb calorimeter (see https://en.wikipedia.org/wiki/Calorimeter). An example can be found here https://arc.aiaa.org/doi/abs/10.2514/3.25795?journalCode=jsr.
Another option is to find a laboratory that performs thermogravimetric analysis (TGA, see, for example, https://link.springer.com/chapter/10.1007/978-3-030-11599-9_7) or differential scanning calorimetry (DSC). From the processing of these data, one can obtain the heat of reaction. An example can be found here Kong Y., Hay J. N. The measurement of the crystallinity of polymers by DSC //Polymer. 2002. V. 43. Iss. 14. Pp. 3873-3878 or here Faleeva J. M. et al. Exothermic effect during torrefaction //Journal of Physics: Conference Series. IOP Publishing, 2018. V. 946. Iss. 1. Art. # 012033; Zaichenko V. M. et al. Thermal effects during biomass torrefaction //Solid Fuel Chemistry. 2020. V. 54. Iss. 4. pp. 228-231.
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C1s peak at 284.8 corresponding to Adventitious Carbon is a reference for the X-ray photoelectron spectroscopy (XPS. However, when using carbon-based support, say Vulcan carbon (rich in graphitic carbon), r-GO and GO for deposition of active catalyst.
The C1s peak in these cases will be dominated by sp2 carbons, not by Adventitious Carbon.
How to calibrate the XPS data in that case?
How to account for the charging problem?
Thanks in advance
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As Jurgen states, the vulcan carbon should have enough conductivity. If using a monochromatic XPS system then analyse without the charge neutraliser on and ensure the carbon is in contact with the spectrometer (e.g. pressed in to a metallic well on the sample bar), then you shouldn't have an issue. The sp2 carbon will be ~ 284.5 eV depending on how well your spectrometer is calibrated.
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Hi, We want to measure the radiation patterns of an implantable antenna. The mimicking gel that we are using has different conductivity than that used for simulations. We want to increase the conductivity of our mimicking gel without increasing the permittivity.
We know that adding sugar and salt will increase the conductivity. However, it decreases the permittivity!!!
Any suggestions?
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I don't have an answer, but a warning. In microwaves and RF it is the refractive index that matters. The real part determines the wavelength and the imaginary part the losses. The refractive index is the square root of the relative permittivity - ignoring permeability. When you take the square root of the complex relative permittivity, it halves the angle of the complex number as well as taking the square root of its length, and the imaginary term in the permittivity, which will be changed by changing the conductivity, will result in the real part of the refractive index being changed. If you want the real part of the refractive index to be unchanged, it may be necessary that the real part of the permittivity falls a bit if the conductivity increases. It is worth working out the numbers for the real and imaginary refractive index you want and what permittivity that results in.
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I am trying to analyse a certain material in a certain food product via HPLC. However, I crossed problems and tried to correct them but problem goes on.
 After i see baseline in HPLC, i put standards and then my sample vial.
My sample showed a peak more area than standard peaks area. As first correction, i sent more concentration standard to HPLC column, Then i recognised that my sample peak got increase. As i increase standard concentration, peak of sample getting increase
As second application, i tried diluting sample concentration. Firstly i sent standards then i applied samples which are different concentration. But it didnt work well. For each diluted sample i read two times but machine didnt read peak of sample accurately. While first parallel showed a peak, second parallel didnt show any peak. 
I cleaned HPLC column with mobile phase but it didnt change results. After cleaning of column i get a baseline but while reading samples, it doesnt show peak each time.
What is your recommendation for this problem?  
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I have no specific experience, but it sounds like you have a source of urinary acid , like an ester. At that pH this ester is breaking apart at the ester bridge giving you more urinary acid than expected. Try increasing the pH of the mobile phase to 3, then 4, then 5 and check your peak.
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Hello everyone
Based on the calculation of the enthalpy peaks of crystallization and melting of the DSC test of the provided PLA sample, the crystallinity degree is 12.2%. I don't know if this achieved percentage is logical or not. Kindly, take a look at the attached result and tell me if my calculation was right or not.
P.s = the cooling rate was 30˚ C/min.
Best regards.
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Dear Milad, thank you for asking this very interesting technical question concerning the crystallinity of PLA (= poly(lactic acid)). In this context please have a look at the following useful research article which mght help you in your analysis:
Crystallization of PLA-based Materials
This paper has been posted on RG as public full text, so that it can be freely downloaded as pdf file. Also please go through the following relevant reference:
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Is it possible that the mechanism of stress corrosion cracking(SCC), in PLA is related to factors such as the crystallinity of the polymer, the pH of simulated body fluid, and the magnitude of the applied load?
Best regards.
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Dear Milad
The phenomenon of SCC normally occurrs in polycrystalline metallic alloys that are succeptible to a combined of corrosion,i.e.,chemical dissolution, and a tensile deformation. Therefore,the possibility of SCC of PLA is slim to impossible .
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Hello everyone
I use a metal powder as the filler to a thermoplastic polymer matrix. Therefore, I wonder if there are any changes such as the molecular weight distribution, occurring in the structure by adding the filler metal powder?
My regards.
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Dear,
Some pigments can cause property modifications. I have tested PLA with different colors, and they have different tensile strengths.
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Hello everyone
I have done a DSC test on the poly-lactic acid by Mettler DSC set-up. As the result shows, there are three endothermic peaks in the red curve that I marked by the black color. It is obvious that peak number one belongs to the glass transition temperature, and peak number three is the melting temperature, but I don't know exactly what is the type of peak number two. I have this concern that the second peak might be the effect of impurity or a metastable modification in the polymer tested.
Any guidance, suggestion, or opinion would be helpful.
Best regards.
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For a polymer thermal analysis of the type of sample you have, you can first examine the TGA thermogram and identify the temperature range your polymer is stable. T hen, use DSC to heat to the temperature you are certain that your polymer is not degrading. Then, stop heating and cool the sample slowly in the DSC instrument, and start the heating cycle again. Any of those phenomena that are not reproducible, such as polymerization exotherm, impurity evaporation, anthalpic relaxation, etc will disappear in the second heating curve. Although impurity, including residual water, is a possibility for the second peak, what I am concerned is the slight exothermic event right before endothermic event that followed. Impurities usually do not show that. Have you made sure that you do not have residual lactic acid that did not polymerize?
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More Questions: 2. In what form do the Chemical species reside in the Chromite? Why does the nominal composition of Chromite differ from its Chemical analysis? 3. Chemical species that do not occur in Chromite will occur in other valuable minerals or in gangue. Which Chemical species might these be? 4. What valuable minerals might these be? 5. What is gangue? 6. Is Chromite a mineral or a phase in this instance? If it is a mineral, what is its stoichiometry? If it is a phase, what is its stoichiometry? 7. At what temperature would you need to run the furnace so that the Chromite concentrate (the "charge ") drops into a liquid bath? 8. Is this the temperature at which Chromite furnaces typically run?
Question Guidance:
You are an engineer assigned to a ferrochrome smelter. The principal feed to the furnace is a concentrate of Chromite (nominally FeCr2O4). Once a week the concentrator sends through a chemical analysis of the Chromite concentrate. The following summaries that analysis (in mass %) for one week in the year. Cr2O3 46.3, FeO 20.2, Fe2O3 4.0, SiO2 1.1, CaO 0.2, MgO 11.5, Al2O3 14.5.
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@Ntombi Ncube, very helpful. Thanks
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Acetaminophen has a λmax of 243 nm. Why is detection λ of HPLC set at 254 nm?
Environmental Earth Sciences (2020) 79:457
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Dear https://www.researchgate.net/profile/Aarif-Shah-2 , Just ensure that DAD detector is working on VW ( Variable Wavelength ) priciple but UV detector is working on Lambert Beers law principle entirely different . You are again requested to calculate manually % RSD between two wavelengths ( not more than 2 % ) .Please go through the deatail - https://www.ssi.shimadzu.com/products/liquid-chromatography/knowledge-base/hplc-basics/uv-vs-pda-detectors.html
Further manual calculation of % RSD are suggested since two instruments are on defferent platform .
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How do you calculate fixed carbon in biomass?
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You can have a glimpse at these papers.
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I am doing an assay in which Dextran molecules are dissolved in cell culture media (Endothelium growth media - Plus) and the project is being conducted within a BSL3 lab. In order to remove things from the BSL 3 lab, they have to undergo 1 of 3 inactivation processes (Chemical, UV-inactivation, or Heat inactivation). I am reading my dextran molecules via fluorescence so UV will likely ruin the dextran molecules, and heat inactivation is also likely to ruin the dextran fluorescence.
My question: Is there a viral/BS3 chemical inactivation technique that will leave my dextran molecules intact? Formalin? Paraformaldehyde? Methanol?
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Adam B Shapiro The dextran is fluorescently labeled. Sorry if that was unclear.
I need to take the media out of the lab because I am analyzing the media itself after the experiment. We use a plate reader located in our normal lab space.
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hi
i want to use sodium borohydride (NaBH4) as the agent for reducing metal ions on CNT and obtain metal-coated CNTs. i have a few questions:
1. if my solvent is ethylene glycol, can i use the same for NaBH4 solution or can i add NaBH4 as powder?
2. how can i calculate the right amount of NaBH4 required to perform this reaction?
Cheers
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NaBH4 can easily undergo solvolysis with protic solvents resulting in the generation of hydrogen and borates:
Therefore, a major point you need to be careful about is keeping everything cooled. An example in which this combination was used successfully can be found in the following work, maybe the process parameters from there can be partially transferred:
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Hello,
I am looking for chitin reference material for chemical analysis. I found this reference material:
However, I am looking for a second one similar to this one. Does anyone know of a producer/company selling those?
Clement
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I used used 1 mmol chloramphenicol as template, 5 mmol MAA and 25 mmol of EGDMA. First I tried in 5 ml of chloroform, it formed partly hard solid and partly slurry after 2 hours.. then I used same mixture but in 50 ml of chloroform, it form slurry.. even I used more chloroform as porogen and solvent, I couldn't get the spericals MIP as mention in some journal.
Why it form slurry and why it form hard solid as I used same amount of chloramphenicol, MAA, and crosslinker?
Whst should I do to get the spericals MIP in large amount so no need to crushed it?
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Maria Monica Sianita Ali Nematollahzadeh I am unable to obtain the precipitation product of MIP polymerization using the same chemicals as mention above.
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I am looking for bio-based Succinic acid pricing information and would also like to know a few companies interested in buying-selling it.
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There is bound to be disparity in the chemical content of ores tested using wet analysis and electronic device placed in direct contact with the dry ores. Do you agree? Let's have your views.
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Yes there is bound to be disparity because one result will depend on the direct impact of rays emanating from the device in contact with the ores while the other result is affected by the level of dissolution of the ores, the reagents used and also the rays from the testing machine.
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Is it possible to calculate entalphy of LiBr/H2O or another solution if we know correlation of specific heat without using any software?
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If you want to solve your problem as it appears in the image, I recommend using an equation of state for the enthalpy departure.
I also recommend the following articles:
-A computationally effective formulation of the thermodynamic properties of LiBr-H2O solutions from 273 to 500 K over full composition range
- Exergy calculation of lithium bromide-water solution and its application in the exergetic evaluation of absorption refrigeration systems LiBr-H2O
-Thermodynamic Evaluation of LiCl-H2O and LiBr-H2O Absorption Refrigeration Systems Based on a Novel Model and Algorithm
-Mathematical Model of a Lithium-Bromide/Water Absorption Refrigeration System Equipped with an Adiabatic Absorber
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Why is the enthalpy and entropy values of aspen plus different from engineering equation solver? Are there any conversion methods?
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Each software may be using a different reference state.
To check if this is the case or not you can use a simple trick.
Just try and calculate the enthalpy or entropy difference between two states from the two software, (the same two states). If everything other than the reference state is the same, this should give you the same answer.
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why NIST database in ASPEN PLUS have not LIBR+H2O for experimental data ?
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Hello there.
There are many compounds that are not found in ASPEN databases, new ones are incorporated in each version, but many are still missing.
One option that you have is to be able to create pseudo components and add them to ASPEN.
I leave you some tutorial links.
Regards.
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I am trying to model a single-effect absorption refrigeration system using LiBr/H2O in Aspen Plus. Who can help me model the absorption cooling system? Please send a private message.
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Sampath Suranjan Salins I am talking about aspen plus not ansys fluent.
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How can I define the following mixture in Aspen Plus:
"Potassium formate-Water-AL2O3"
If you know, could you please explain step by step via some screenshots from Aspen Plus ?
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Is this Ansys Fluent analysis? its multiphase flow problems. U need to model the packing first the define the desiccant and material. Then apply suitable boundary conditions to solve the problem.
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Although there are already studies in the literature but not much , the use of potassium formate/water or potassium formate+LiBr/Water are not available in the commercial sector for absorption refrigeration systems? what is the actual reason ?
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Dear Cenker Aktemur I found a report on the use of potassium formate/water (see attached) in which some severe corrosion problems were observed. They are listed on p. 21 of this report:
Besides very good results in thermal aspect, Freezium and Pekasol 50 exhibits some problems in material compatibility. This could be summarized as:
- We have observed very aggressive reaction to zinc;
- Copper pipes in contact with copper were covered by blue/green (somewhere some white layers formed at the top of this coating);
- All steel surfaces where coating was damaged corroded significantly;
- Some gaskets in valves were damaged and valves leaked.
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We doubt that some people add urea in fish based food item, any one can suggest some method by which we can detect the uear qualitative and quantitativly.
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This is a common issue everywhere. you can try this
and
not sure but people can also add melamine to fishmeal to artificially increase protein content.
Kangning, L. I. U. X. J. I. A. G., and WU Xiuquan WU Caimei. "A Study on Qualitative and Quantitative Detection of Melamine Adulterated in Fish Meal by Fourier Transform Near Infrared Spectroscopy [J]." Chinese Journal of Animal Nutrition 3 (2010).
You might want to detect melamine in fishmeal and also in aquacultured fish or even poultry
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I am interested in post-synthethic methods of this material, and would like to know the chemical stability of Bi3Te2 (particularly nanotubes) in water, acid o alkaline media.
Any literature regarding this aspect (no matter if it's in bulk) is much appreciated.
Thank you.
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Brilliant!
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How can i increase the pH of sea water to 12? Because when i adding NaOH to seawater the pH does not go above 10 and begins to precipitate.
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Coloque el agua de mar en un baño de maría con hielo para mantener el agua fría y agregue lentamente NaOH hasta que alcance el PH 12.
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Hello,
I am having a debate with some colleagues about how we believe a non-stoichiometric oxide would be observed in XPS. Let's say we have an oxide in the form of AB2-x (A = transition metal, B = oxygen), in which x = 0 - 0.5. The sesquioxide AB1.5 has the oxidation state of A(III), and the dioxide AB2 would be the A(IV) state. Would an intermediate phase in a graded stoichiometry (e.g. AB1.75) appear as a superposition of A(III) & A(IV) chemical states, or would it appear as its own intermediate doublet pair? This would mean it has a binding energy for each main line that falls between the A(III) & A(IV) binding energy values, not necessarily being attributed to either of them.
Would the lack of oxygens atoms in the coordination lead to an intermediate mixed oxidation state with A(III) & A(IV) states both present in an amorphous oxide?
My thinking is that even for an intermediate non-stoichiometric oxide, you would still be able to construct a fit from the A(III) and A(IV) chemical species. The contrary thinking is that each non-stoichiometric oxide would be shifted in binding energy position between the A(III) and A(IV) main lines.
Please let me know if I can clarify this question.
Thank you.
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Dear Dr. Keith White ,
I suggest you to have a look at the following, interesting papers:
-Non-stoichiometric oxide and metal interfaces and reactions
R.A. Bennett, J.S. Mulley, M. Basham,·M. Nolan,·S.D. Elliott,·P.A. Mulheran
Appl Phys A, 96: 543–548 (2009)
-Non-equilibrium Oxidation States of Zirconium during Early Stages of Metal Oxidation
Wen Ma, F. William Herbert, Sanjaya D. Senanayake and Bilge Yildiz
Papers: BNL-111675-2015-JA
-Study of SiO2/Si Interface by Surface Techniques
Rodica Ghita, Constantin Logofatu, Catalin-Constantin Negrila, Florica Ungureanu, Costel Cotirlan, Adrian-Stefan Manea, Mihail-Florin Lazarescu and Corneliu Ghica
Chapter of book: Crystalline Silicon - Properties and Uses (2011)
-New insight on early oxidation stages of austenitic stainless steelfromin situXPS analysis on single-crystalline Fe-18Cr-13Ni
Li Ma, Frederic Wiame, Vincent Maurice, Philippe Marcus
Corrosion Science, Elsevier, 140, pp.205-216 (2018)
-Direct observation of pure pentavalent uranium in U2O5thin films by high resolution photoemission spectroscopy
T. Gouder, R. Eloirdi & R. Caciuffo
ScientificREPORTS, 8:8306 (2018)
Best regards, Pierluigi Traverso.
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I and my friend was conducted a research about primary productivity in fish pond using dark and light bottle. However, we got some problems because dissolved oxygen (DO) in dark bottle after incubation (approx 12 hours) is higher than initial DO. Could someone give us explanation why it happens? 
Thank you
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it might be air bubble filled your bottle before sample and after sample also
just check the error.
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The third rotation allegedly leaves the molecule unchanged no matter how much it is rotated, but is it really okay to assume this? A response in mathematics is welcomed, but if you can explain it in words that would be good, too.
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Dear Cory Camasta, Three degrees of freedom come from free motion, one from rotational and one from vibrational & E= 5/2 KBT. The remaining rotational degree has a very small moment of inertia as some participants noted previously.
See the following external post for the full explanation regarding the separation of levels mentioned by Prof.
Gert Van der Zwan
:
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I have metal matrix composite containing some unknown amount of hBN. I want to know the amount (wt%) of hBN. Can anyone please suggest the technique like spectroscopy or chemical analysis?
I will be thankful for guidance.
Thanks
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Thank you for your response.
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How can concentration in terms of rich and poor be affected by adding nanoparticles to LiBr-Water?
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Dear Kenkar,
In diffusion absorption coolers regarding to the heat performance of the system, ammonia/water couple with alumina (Al2O3) particles in nano-size can be a better option. It can provide better absorption of heat from the generator and faster evaporation of the cooler from the cooling/absorption fluid. Considering the effect of fluids containing nanoparticles the connection units of the heat transfer in the system operation time of the system might be reduced due to shorter heat transfer periods.
Ashish
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what are the drawbacks of using R744 in cascade refrigeration systems compared to R41?
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Dear Nicholas,
That is true., By taking care of R41 which is flammable , performance value can be increased.
Ashish
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I'm performing a electrochemical experiment, which should produce hydrogen peroxide, what techniques should I employ to reliably detect it from the solution, also what will be the best way to quantify the production?
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from above link you can know recent methods to determine H2O2
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I would like to analyse monocarboxylic acids higher than C20 (at least up to C30), but I cannot find a company for buying them. I prefer a mixture of more acids in an organic solvent but it can be solid standards. Thank you
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Hi,
You may make an inquiry at Alfa Chemistry, they offer kinds of chemicals for research use.
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I Have directed a doctorate thesis on trials of cultiva tion of Pelargonium graveolens in order tout optimize yields and a quality of chemical compounds of this plant extraits. I need scientific collaboration in chemical analysis and their application on cosmetic or food chemistry, the doctorant Can beneficied a short course. Please to purpose us a laboratory to complete study and prepar a scientific paper.
Thank you vert much.
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Thank you dear colleague.
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1.Looking for easy comprehensive and authentic books on analytical chemistry
I am already using
G.D christian
Harris Quantitative chemical analysis
Skoog and west
I just want to explore some book other than these!
2. Do tell me some good precise and easy to understand books on spectroscopy?
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Dear Yasir Iqbal,
One of my favourite book is the encyclopedia of spectroscopy and spectrometry (John C. Lindon, George E. Tranter, David. W. Koppenaal ; Eds), 2010. I would also recommend some other books specialized in NMR and fluorescence.
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Chemical analysis of layers of ice (arctic, antarctic) revealed evidence of climatic changes occurring long before human started polluting our planet-
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interesting question
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Recently my supplier delivered steel with the composition 0.04 C, 0.7 Si, 4.7 Mn, 21.8 Cr, 0.5 Cu, 0.45 Mo, 0.3N, 0.7618Ni, 70.2381Fe (chemical analysis report attached ), I am not sure about the grade of the steel as it is magnetic.
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Dear Jayant,
There is no information about Ni content, but at first sight it fits S32101-lean duplex steel. This steel grade contains from 1.35 to 1.7%. Ni. The two-phase structure is magnetic.
Compare e.g. with: Niagaj, J. (2012). Ferrite content measurements in S32101 lean duplex stainless steel and welded joints. Archives of Metallurgy and Materials, 57(3), 779-787.
Maybe someone has a different idea?
Best regards,
Dariusz
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I have had great success with Tasmota firmware on a dozen Sonoff basic devices and a couple of TH16s.
I'm looking to go deeper and if possible create code for a chlorine level capacitive level detector.
Using a concept I have used in the past, with a 32 bit 8 core microcontroller, of applying a voltage momentarily to a capacitor to an output Pin, while simultaneously starting a counter, switching that pin from output to input, then when the voltage on that same pin falls to 1/2 VCC the counter stops and that count value is compared. The 1/2 VCC threshold was simply when the state of the now input pin transitioned from on to off.
I'd like to do a similar thing using the ESP 8266 with a couple of large plates on the outside of a plastic chlorine tank and determine the approximate level based on how long it takes to charge this crude capacitor which should vary via tank level.
I'm not looking for super high accuracy like +/- .1" but something +/- .5" would be sufficient.
While I am quite adept at programming in Assembly, my C skills are standard & basic in python.
I'd like to make this part of my Node Red Home Automation system running on a Raspberry Pi so as to monitor the tank's chlorine level via my cell phone.
Anyone use the ESP8266 for this or similar purpose? Ideally I'd like to use a Sonoff Basic as it has the power supply and is self contained. I'd obviously have to add some external leads to the tank's capacitor plates.
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Mohamed-Mourad Lafifi Thanks a lot for helping me & taking forward to my research!
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I have seen recent papers about this technology. However, the great majoritty these don´t explain the concept in depth. Can anyone help me? Can anyone indicate some reviews about this subject?
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A biosensor generally consists of at least two functional components: a molecular recognition element (receptor) that selectively interacts with its target analyte (e.g., ions, DNA, antibodies, cells, and microorganisms) and a physicochemical transducer. The latter converts the bio-recognition information into a measurable quantity, being an electrochemical, electrical, optical, magnetic, mass-sensitive, or thermal signal.
Due to the fact that biological analytes are often hard to detect purely on basis of their intrinsic physical properties, biosensors often require labels such as enzymes and fluorescent or radioactive molecules attached to the targeted analyte. As a result, the final sensor signal corresponds to the amount of labels, representing the number of bound target molecules. As a drawback, label-based technologies are often labor- and cost-intensive as well as time-consuming. In addition, labeling of biomolecules can block active binding sites and alter the binding properties. Altogether, this may adversely affect the affinity-based interaction between the recognition elements and the target molecules.
In contrast, label-free biosensing technologies, by definition, do not require the use of labels to facilitate measurements. Instead, they utilize intrinsic physical properties of the analytes, such as molecular weight, size, charge, electrical impedance, dielectric permittivity, or refractive index, to detect their presence in a sample. Label-free biosensing methods have made enormous progress in recent years due to their ability for rapid and inexpensive bio-detection in small reaction volumes. Moreover, they lend themselves for integration into lab-on-chip platforms and allow monitoring the concentration of target analytes in real time.
See also recently published book: M.J. Schöning, A. Poghossian, Label-free biosensing: Advanced Materials, Devices and Applications, Elsevier, 2018.
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Through casual conversation at the Practical Surface Analysis (PSA) meeting this week in Japan, I have become aware that there is still confusion on the availability and accessibility to terms and definitions in surface chemical analysis. While the ASTM E42 vocabulary document, E673, was widely available through most research libraries in the annual volume of ASTM standards, keeping the document consistent with the ISO vocabulary standard for surface chemical analysis, 18115-1, was difficult, particularly since the ISO document was adopting many more terms and growing quickly. It was decided to withdraw the ASTM document and make normative reference to the ISO vocabulary document in ASTM standards.
As part of this change, several people (Don Baer at PNNL and Cedric Powell at NIST in particular) made great effort in getting ISO to agree to make these terms free and readily accessible. They were very successful in getting this cooperation, and now all of the surface analysis vocabulary terms are readily accessible through the IOS Online Browsing Platform (https://www.iso.org/obp/ui). Now there are several sites also hosting links to this, in order to make these terms and definitions accessible. This is a valuable resource, and is freely accessed to check terminology to be used in publications.
This ISO vocabulary document (18115-1) is also being revised, adding new terms and clarifying those that have been found to be lacking information or that are confusing.  Please use this resource, and if you find that there are necessary terms missing , or if there is confusion in any of the existing terms, please contact Dr. Alex Shard at NPL, who is the chair of TC201/SC1 and is currently actively revising this document. There is also a companion document (18115-2) for terms used in scanning probe microscopy, and these are also available through the ISO Online Browsing Platform. 
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Please look at the following below link and the attahed book which may help you in your analysis:
Thanks
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Hello everyone,
I'm having some issues with lead acetate solutions for some zebrafish toxicity testing. I'm preparing a stock solution highly concentrated in miliQ water. Then I dilute it to 25ppm (our highest tested concentration) in zebrafish medium (E3, pH 7.2) and the solution looks fine. However, after 24h, when I'm changing the larvae to fresh medium, I have these white precipitates all over on the 24h-old solution. My issue is that I'm not sure my larvae are really exposed to 25ppm Pb. And I can't perform chemical analysis to confirm it.
I wonder if someone else got these issues and what's causing these precipitates? I've also realized the pH decreased which is quite bad for zebrafish larvae (lower than 7.2 is not good for their health).
This is the type of troubleshooting problems that aren't explicit in published papers, so I have no clue if other people are going through the same?
Thank you in advance!
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hey, sometimes the sulfate in the medium can precipitate with metals (like Mn), in my medium it was sulfate ions the problem, when I removed them no more Mn precipitates...
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In the framework of the ongoing research project, we will sample pore water from sediments in the mesocosms to investigate on carbon cycling within the system.
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You may follow the method of Burdige et al. (1992) or Sharp et al. (2002).
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Dear Dr. Posz, we are currently working on a project to characterize various Euphrasia spp. chemically by HPTLC, and microscopically, to see if these species can be distinguished by chemical analysis. We are looking for additional samples of Euphrasia, in particular from Eastern Europe since this is where most of the commercial material is collected. In addition, we are interested in authenticated samples of Odontites species, since these are often sold labeled as "Euphrasia".
Please let me know if you are willing to help
Thank you so much for considering this
Stefan
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I have made a steel composition and after chemical analysis i found the carbon is beyond acceptable limit however, other elements are within the limit. Is there any way I can remelt the cast structure and add something to bring down the carbon % in steel or may be any other way ?
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Practically it is very difficult to remove carbon from steel by just remelting. Carbon can be removed by introducing oxygen in steel (by blowing, or by addition of oxygen bearing agents like scrap, iron ore, mill scale etc.)
Even by doing so, first elements which has got higher affinity to oxygen will react first like (Al, Si etc), and your whole chemistry will be disturbed.
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Lot of research is going on to invent an alternative source of conventional fuel in place of Diesel because petroluem fuels are depleting. Out of which, biodiesels are found to be reliable source of fuel however, this suffers with high NOx emissions. Exhaust gas recirculation has been used to reduce the same. Various forms of biodiesels are prepared and tested (performance wise, exhaust gases and chemical analysis) and found suitable to use in diesel engine. However, there is a limited usage. What could be its limitations in brief?
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