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I would like to know if it is advisable to use any of these processes ( silylation, alkylation, acylation and chiral derivatization) to produce a more volatile and thermally stable compound using GC/MS for pharmaceutical analysis in water samples?
The idea is to reduce polarity of compounds and eliminate the active hydrogens with any of these groups: silyl , acy, alkyl, & chiral derivatization agents. In other words, can an acy group do the work of a silyl reagent?
Please any potential explanation for ...?
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For GC, there are three basic types of derivatization reactions: silylation, acylation, and alkylation. Silylating reagents react with compounds containing active hydrogens; these reagents are the most common type used in GC. Acylating reagents react with highly polar functional groups such as amino acids or carbohydrates. Alkylating reagents target active hydrogens on amines and acidic hydroxyl groups.
this link can help you choose the most efficient derivatization method for your sample
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While working on method development and simultaneous determination of two drugs, we have experienced that peaks of the plasma appear in between the peaks of two drugs. The retention time of the first drug was 2.69, while plasma peaks appeared between 3.3 to 3.7 min however, the retention time of the second drug was about 6.692 min. one drug was eluted earlier than the plasma and the second drug was eluted after the plasma. Is there any issue in acceptance of such method?
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As per my experimental experience, it is surely possible. The main concern is the effect of the matrix. Another point to be noted is that the first peak is coming out very early and it will be highly affected by the matrix in your case plasma, hence unsuitable for developing the bioanalytical protocol. As such a normal RHPLC protocol will not work, u also need to add an internal standard to maintain the integrity of the data. Furthermore, plasma peaks will not be stable so I don't think they will remain in the same place throughout the analysis.
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The concentration of aqueous solution of ibuprofen can be measured by using UV-VIS?
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Yes you can.
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Dear to whom it may concern,
I wonder whether benzopyrylium ion is permanently or temporarily positively charged because I would like to convert its positive charge to its neutral form.
Would you mind if you may give me some suggestions in this case?
Best regards,
Khoa.
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If you do that, you can destroy the ring system or by reaching a ring opening, get benzopyran or a substitution
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When the drugs overlap absorption at lambda max. then, how to calculate unknown concentration of both drugs with absorption correction method.
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In order to derive the concentration of a sample from its absorbance, additional information is required. ... Absorbance Measurements – the Quick Way to Determine Sample Concentration
  1. Transmission or transmittance (T) = I/I0 ...
  2. Absorbance (A) = log (I0/I) ...
  3. Absorbance (A) = C x L x Ɛ => Concentration (C) = A/(L x Ɛ)
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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,
I have been developing one sample preparation method for environmental samples. Hence, I am considering some of the carbonaceous adsorbents: Graphitized Carbons and Carbon Molecular Sieve.
As far as I know, graphitized carbon adsorbents include two types: porous graphitic carbon (PGC) and graphitized carbon black (GCB). However, I have no knowledge about carbon molecular sieve as well as the differences between graphitized carbons and carbon molecular sieve.
May you please spend a little time giving me what you suggest as well as your tips?
Thank you so much,
Khoa.
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Actually for the environmental samples, GCB is good enough, however, it depends on the analytes for which you are intended to use Graphitized carbon Black, sometimes, the recovery is seriously affected if it is used as large amount. Anyway for the carbon molecular sieve, you may visit the following link:
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Hello all 
I am working on drug molecule cilnidipine
trying to develop dissolution medium for in vitro release of my formulation
can anyone help me with the idea how to do it?
 i have tried following disso mediums but none of them show peak of my drug
0.1 N HCl
Phosphate buffer pH 6.8
Acetate buffer pH 4.8
Phosphate buffer pH 6.8 with 0.1 % tween 80
0.4 % SLS in deionized water
also can anyone tell me about authenticity of using methanolic buffer / solution as dissolution medium?
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Can anyone help me regarding how I can make a formula of Cilnidipine Tablets meeting dissolution as per JP monograph.
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I conducted an assessment studies on wastewater for the presence of pharmaceuticals and all values after working back to original sample of 1L were below the limit of quantification of the method of analysis used
How should the data be reported in a manuscript?
Ps: I used SPE in concentrating the 1L to 2ml for the HPLC reading and afterwards the obtained values were converted to back to the concentration in 1L
Thanks in advance for your answers
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You can report as BQL(Below Quantification Limit) and specify the Linearity, Range, LOD(Limit of detection) and LOQ(Limit of quantification) in separate table.
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I want to make a thesis about how can conductivity affect the dissolution testing of oral dosage forms of drugs. If you have information please help me.
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When Water is used as dissolution media, You have to be careful for pH and conductivity. Actually water should be passed as per USP criteria. pH and conductivity has important role in some critical drugs for dissolution. some drugs have pH dependent solubility. some drug's solubility also effected by minerals so conductivity is also a factor.
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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,
May I ask you about the difference between porous graphitic carbon (PGC) and graphitized carbon black (GCB) in terms of surface properties, retention mechanisms, and redox potentials?
Thank you so much,
Quynh Khoa Pham.
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I think the following link will be very much useful to know about porous graphitic carbon and GCB as well:
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Dear Chromatographers,
This method was developed on LC MS/MS. The quantifier for both analyte and internal standard have same product ion, will that have an impact on overall analysis. Any supporting article to read more about this would be very helpful.
Thanks
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Hi,
For those having a cross-talk problem, it is better to choose the deuterium or carbon isotope dilution method for internal standard (IS) quantitation. If you cant provide the isotope synthesized molecule or co-elution exist and you cant improve the chromatographic resolution then I strongly suggest switching your IS with an analog molecule, which behaves like your target compound (Extraction yield, ionization suppression effects etc.) but also giving fragmentation product at different MW far away from your target fragments.
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I would like to label Human Serum Albumin for my experiments.
My supervisor suggested NHS and 6-Aminofluorescein as working agents.
Can anybody please suggest a working protocol?
Any suggestions on storing? Can I freeze the labelled protein in a solution?
If you have any other suggestions I would be very grateful!
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Obviously numerous examples of how you can perform the labelling can be found. It depends on whether you use the label(s) separately or as an already prepared ready-to-use sample like in:
In essence it comes down to the use of NHS in order to enable the fluorescein to get attached to your protein. Once the labelling is finished you need to rid of the excess of NHS and 6-aminofluorescein. In:
you see that they use dialysis to remove the excess of NHS and 6-aminofluorescein. In:
Bidmanova, S., Chaloupkova, R., Damborsky, J., & Prokop, Z. (2010). Development of an enzymatic fiber-optic biosensor for detection of halogenated hydrocarbons. Analytical and bioanalytical chemistry, 398(5), 1891-1898.
the conjugates (CF–BSA) were separated from unreacted dye by size-exclusion chromatography.
Your question about storage. Indeed you can make one stock solution (let say 20 mL) and make smaller portions (let say 0.5 mL) and freeze them. Once you take a portion out of the freezer you better use it one time and better not freeze it back again (to be one safe side).
Best regards.
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Most of the researchers working on protease inhibitory assay, they cited the Oyedepo etal, 1995, but I couldn't get the original paper. I followed their protocol, replicated 11 times, but unable to get the readings as absorbance was read very high. Even the Aspirin and Diclofenac sodium at the dose of 10-100 microgram/100 microlitre as well as 1-100 microgram/ml could not give the reading . I am wondering why I can not get the readings even on standard drug following their reported protocol. Does Trypsin (0.06 mg) have any specific concentration in their protocol ?
Oyedepo OO, Femurewa AJ (1995). Anti-protease and membrane
stabilizing activities of extracts of Fagra zanthoxiloides, Olax
subscorpioides and Tetrapleura tetraptera. Int. J. Pharmacog., 33: 65-69.
Please provide any info on the protocol of this paper and suggest another protocol for protease inhibitory assay if possible.
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OK
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Hello everyone,
When I use PDE on Clean Validation (CV) to evaluate the residue of CV, I have a problem that is the unit of PDE (mg/day) is different on 0.1%dose(mg/swab) and 10ppm(mg/swab).
How could I calculate to change the unit?
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Use the MACO formula that contain PDE value.
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Dear all
I read one literature in past, which discusses selection of solubilization technology based on the melting point and log P of active pharmaceutical ingredient.
The faint content back of the mind is:
There were two graphs, Log P on X-axis and Melting point on Y-axis
[1] Dose is less than 100 mg, what are the zones, where you choose (1) nanonization (2) liquid filled capsules and (3) solid dispersion as solubilization enhancement technology
[2] If dose is greater than 100 mg, then the similar selection based on zones
COuld you please help me find this reference?
This article is really a good read.
Thank you
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Dear Dr. Andrei Blasko
yes, I do agree with your comment. Solubilization of pharmaceutical compounds is a complex phenomenon and there are factors other than MP can affect the solubilization.
Moreover, in vivo conditions that include but not limited to presence of bile salts, pH of different parts of GIT, and mechanical movements can have further impact on the same.
You may check the paper that I mentioned in previous comment to this thread (link copied below). This publication summarizes various tools to support formulation development based on physicochemical properties of poorly water-soluble pharmaceutical molecule(s).
Sincerely
Samarth
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Hello everyone! The problem with amoxicillin is that it is easily degraded in the environment. I haven't found any studies on the environmental presence of its metabolites (e.g. AMX-S-oxide, AMX penicilloic acid, AMX diketopiperazine). How do I find indicators of its true concentration and why aren't the metabolites investigated?
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LC-MS or other HPLC options.
regards,
GB
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The global average surface temperature rose 0.6 to 0.9 degrees Celsius (1.1 to 1.6° F) between 1906 and 2005, and the rate of temperature increase has nearly been doubled in the last 50 years. Temperatures are certain to go up further and may lead to fast genetic mutations in some pathogenic microbes to become accustomed to the new climate and proliferate resistant gene distribution over geographies. In addition, the overuses of antibiotics is also triggering the issues at a great step. Near about 10 most deadly bacterial pathogens have already been registered as antibiotic-resistant. Mycobacterium tuberculosis is one of them, that has already been created a huge challenge to overcome in their own right and will only become harder to control as their resistance to antibiotics grows. The development of new antibiotics is slow and difficult work but bacterial resistance is decreasing our arsenal of existing drugs posing a catastrophic threat as ordinary infections become untreatable.
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Addressing the global shortage of, and access to, medicines and vaccines
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I am looking for studies that surveys pharmaceutical drugs on the market (in the US or internationally) and analyze drugs by form (solid, liquid, semi-liquid). I am not necessarily interested for method of administration.
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Several reports related to African and Asian countries mention that the menace of counterfeit pharmaceutical products is a global menace.
This information is based on effective measure to determine this or this news has been spreaded beyond proportion ?
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Counterfeit pharmaceutical product is a biggest challenge especially where pharma regulation is weak.
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I have the diffractogram of a compound with 3 different types of polymorphs, form A, form B and form C.
Looking at the diffractogram, the 2-theta peaks for form A and form C looks identical, however the absolute intensity (counts/cps) is different. Both diffractogram for form A and form C are from two different parties. My questions will be:
1) If the peaks look similar for form A and form C but having different absolute intensity, are these two different form?
2) Is there are possibility that the difference in absolute intensity caused by sample preparation or due to different XRD machine?
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The difference in peak intensities is correlated to the cation distribution in the occupation sites of the structure. If the positions of the peaks are identical, it is quite acceptable to be considered as identical structure.
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I am working on a mixture of three different API in my product. Their peaks are merging with each other. I would like to use chemometrics to solve my problem. Please suggest.
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Do you have the chromatograms for each of the individual API's? Is your detector a fixed WL or DAD? If you share (in a general format - Excel, tab delimites, comma separated values, etc) the mixture chromatogram data as well as the individual API chromatograms I can try to take a look and give you some feedback. Regards, Luis
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Hello All,
Which methodology should I follow to measure water activity of pharmaceutical materials?
I am aware that there are two USP procedures in this regard, chapter 922 and 1112. Which of these is the most correct? Also, would you be able to provide full document of any of these?
Finally, is thee any alternative method to the USP ones?
Many thanks in advance,
Antonio
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I am working on a mixture of three different API in my product. Their peaks are merging with each other. I would like to use chemometrics to solve my problem. Please suggest.
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Dear Bhupendra Shrestha , When you mention three API peaks, are you referring to 3 chromatographic unresolved (partially overlapping) peaks? If yes, it seems you are trying to circumvent an analytical problem by using numerical tools instead of solving the problem itself (by optimizing your analytical method/procedure). I can tell you that you are, most probably enlarging your problem as you will need, when submitting a MA or a Variation to a MA, to properly justify and validate the use of “numerical/chemometric” methods in the quality part of the regulatory documentation. At that stage you will, most certainly, be asked to redo all the product development using properly validated procedures!
If you are working in a very early phase of the drug product development (with no GMP compliance) and with a tight budget I would recommend trying R or Python as they’re free to use – but again you will not most probably (I’m just guessing) be solving your problem.
Unscrambler X as well as OriginPro are commercially available and quite powerful - but not cheap.
Hope it helps, Regards, Luis
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I am doing an experiment on the change of viscosity of a gel sample after freeze-drying and reconstitution. I took 3 measurememts of the gel before freeze-drying and the same for after freeze-drying/reconstitution. The results on the viscosity at no-shearing state are 132/128/90 Pa.s before freeze-drying and 90/112/120 Pa.s after freeze-drying/reconstitution. My main question is that does the viscosity really change after freeze-drying. Before answering that, I have some questions about statistics:
Are these results enough for me to make a conclusion?
- If yes, can I say directly that the viscosity decreases after freeze-drying (because it seems really to decrease, but for me it is quite a subjective conclusion) or do I have to do a statistic test and what test should I do (eg T-test)?
- If no, how many measurements should I take in this case? And then how can I conclude if there is a change or not?
Thank you in advance for your opinions.
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2 sample t test is a special case of one way ANOVA where the no. of treatment levels(before and after freeze drying) of the factor is 2, it tests the statistical hypothesis that the two treatment means are equal under the assumption that the corresponding population variances are equal.
The t test therefore depends on two issues , the magnitude of difference of your sample means and variation at the individual treatment levels, for a given sample size, and given difference of sample means, there is a greater chance of null hypothesis being rejected when sample std. deviations at individual treatment levels are small than in the situation where the sample std. deviations are larger.
In the case of your problem i suggest you go with a larger sample size , e.g 10 measurements at each treatment level, but before applying the t test do an F test to validate the assumption of equality of treatment level variances , if the assumption is not met, application of t test on raw data will not be useful.
Lastly using statistics you cannot prove or disprove anything , what the t test will give you is whether there is sufficient or sufficient evidence of your null hypothesis to be true at the pre chosen level of significance.
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Hi everybody,
I need to quantitatively separate vegetable oil from a w/o emulsion in order to determinate the oil content and perform further analysis (such as saponification) on the separated oil. How can I achieve this purpose? The emulsion contains about 3% of oil, Tween 80 as emulsifier and thickening agents. Thanks for your answers!
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It is necessary to separate organic phase (vegetable oil + TWEEN) using simple liquid-liquid extraction. Extraction by equal volume of chloroform or hexane-chloroform mixture would be quite efficient. It should be noted that usual and well known Folch or Radin-Hara alcohol-based extraction methods must be used necessarily to extract MUCH MORE polar lipid components such as phospholipids, monoglycerides or nonesterified fatty acids (but vegetable oil almost completely consists of non-polar triglyceride components and is effectively extracted from water matrix with organic liquid of rather low polarity).
If the water and organic phases of extraction emulsion are poorly separated due to the presence of TWEEN detergent impurity, add a few drops of ethyl alcohol and, possibly, centrifuge or filter the mixture. Then organic extract is evaporated using vacuum or a weak stream of nitrogen.
The sample obtained is ALMOST pure plant triglyceride, since the detergent (TWEEN) is usually added in very small concentrations (up to 1–2% by weight of the substance to be emulsified) to produce an emulsion. Thus, the presence of detergent will have almost no effect on the results of subsequent titrimetric or chromatographic determination of plant triglycerides (the values of the own relative errors of these methods exceed the error introduced by such an insignificant impurity content).
Nevertheless, it is possible to easily separate low polar oil triglycerides from rather polar polyhydroxylated TWEEN by solid phase extraction: the sample is deposited in the cartridge prepacked with silica gel (for example, BONDELUT or other – take sorbate no more than 2% by weight of silica gel). Triglyceride is eluted quantitatively with pure chloroform thus being separated from TWEEN (polar TWEEN may be eluted only by means of much more polar chloroform-methanol mixtures).
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We have tried with Accucore C18, but we found colistin has an affinity to the column materials, therefore it exist in blank.
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  • You can use 30M sodium sulfate and acetonitrile as the mobile phase.
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Hello to everyone. Does anybody could share a protocol or technique for tissues collection from rabbit eye for pharmaceutical analysis? I need to collect cornea, bulbar conjunctiva, aqueous humor, iris ciliary body, vitreous body and retina. I will be thankful for any information.
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Thank you, Varun!
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I'm searching data of prescription of carbamazepine and sulfamethoxazole in some nations in some years. Who knows a web site, or a survey that can be usefull for me?
The kg/year consumption I'm searching are:
-Sulfamethoxazole in China in 2005
-Sulfamethoxazole and Carbamazepine in Spain in 2007
-Sulfamethoxazole and Carbamazepine in Italy in 2004
-Sulfamethoxazole and Carbamazepine in Sweden in 2003
-Sulfamethoxazole and Carbamazepine in UK in 2007
-Sulfamethoxazole in USA in 2001
-Carbamazepine in Austria in 2016
-Carbamazepine in German in 2006
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Very good question! I have students looking into carbamazepine ADR's.
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Drug release study requires taking absorbance of samples at absorption maxima (Lambda max) of drug. What should be the approach in case of poly herbal formulation (nanogel). There are atleast 5 active components in the nanogel with different absorption maxima.
In this case, at what lambda max should the absorbance be taken?
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you can use HPLC with program sequence of diffrent lamda maxima & can anlyze the release quantity of drug.In primary stage you have to validate your method.
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In dissolution test for Abilify 5mg (aripiprazole) Results show high results about 110%, while maximum result should not exceed 104%(max. result in content uniformity test).
This problem does not happened in Abilify 10 or 15 or 30mg.the different in Abilify 5mg is the colorant which is indigo carmine aluminum lake (E132).
When i run the dissolution test with placebo tablets (without active) it give results about 6%.
Dissolution medium contain KCL and 0.2N HCL. PH 1.2
The same method used for all types of Abilify tablets
UV- visible at 249nm , rpm 60 for 30 min.
So, if the reason is the colorant, how to avoid it?
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Determine absorbance of your samples using a blank solution made with the placebo of the formulation containing the lake colorant, to substract the effect of such colorant.
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Which (natural) polymeric carrier system would be suitable to carry poly-phenols (derivatives) as an anti-diabetic drug, orally?
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Thank you for your recommendation.
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The dissolution test results for a particular product have a high variability and are very high. What is the upper limit for the amount of drug released in dissolution testing?
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@Vipul, Would you be so kind to clarify what do you actually want to know (please take a look to my previous post)?
@Md R Khayer. Would you be so kind to let us know to which "dissolution guideline" are you  referring to? And where is the 85-115% drug dissolved (wrt label claim) requirement stated?
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what bacterial-cell wall component that must not be in any pharmaceutical products?
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Lipopolysaccharides, endotoxin containing fragments and mutagenase fragments.
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I am preparing a film containing asenapine maleate. How should I select the composition of the dissolution medium?
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Agree. Use a buffer that has pH of saliva
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How can the interference of excipients in the dissolution results be minimized when the quantitative procedure is by UV-vis spectrophotometry?
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Try standard addition (spiking) method.
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Hi, I am preparing liposomes with drug loaded inside them. I would like to quantify the drug inside them through HPLC. There is an established HPLC method for that drug.Somehow I am not able to see the drug peak, and many other peaks are coming up ( I am able to see the peak with standards but not with the liposomes). I speculate this may be due to phospholipid interference. For extracting the drug from liposomes, I am using methanol as drug is soluble in it. Any suggestions please?
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You have not provided any detailed sample information, HPLC conditions, detection types or information at all. This type of basic information is needed to reply.
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After Preparation of Liposomes-containing Bevacizumab using dehydration-rehydration method , sample was centrifuged,then concentration of avastin in supernatant was measured with BCA method.
Strangely  the amount of protein in supernatant is a bit higher than tatal protein. So encapsulation efficiency (EE%) is negative! Do you think it is because of Experimental error or there is something else in reaction that  has aborbance?
 
thx
 
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I found that bradford and BCA are not suitlable for my goal. They interfere with lipid. so results seems weird. 
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I have some tablets, which contain Amlodipine, Valsartan and Hydrochlorothiazide. There is no problem with dissolution test and all results are within acceptance criteria but I get low assay values  for all active substances (especially for amlodipine). I perform a HPLC method, with these conditions: 4.6-mm*5-cm; 3- micron packing L1, column temperature: 30, as mobile phase I use water and acetonitrile in 15 minutes gradient system. The UV detector works in 225 nm. 
I would be grateful, if you could help me.
Thank you
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When doing dissolution test, what is the method used in quantification.
I think that the problem is in solubility of amlodipine and valsartan , so you should add something to enhance solubility such SDS, or to make Amlodipine as a salt.
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I've been preparing a film of hyaluronic acid intended to administer in the skin. My main objective is to prepare a film that can dissolve really quickly in the skin surface. Despite Hyaluronic acid itself being a high-molecular-weight polysaccharide, I also added Polyvinyl alcohol as a film forming agent. Additionally, I introduced sodium starch glycolate as super-disintegrants as well as gelatin to make the film melt away rapidly. However, I haven't got the success as much as I would have liked. What would be the best strategies for rendering the film dissolvable in normal skin condition? Thank you.
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incorporate some ester linkage between the copolymers that will allow the fast degradation 
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Hi, Im working on a small molecular weight drug which is about 25 kDa. I want to compare it with existing large molecular weight drug which is about 150 kDa. So im wondering which drug has better ADME properties in body or say what are the pros and cons of small weight drug compared with large weight drug? Thanks a lot
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Hi,
Since ADME properties have four major components, so the effect of each of them will not be same.
As I can infer from your question that the smaller molecular weight drug will probably have higher surface area which will enhance its absorption capability within the cellular membranes. Also, it will be widely distributed in the blood. But this wide distribution will have subsequent side effects also.
The most important parameter is metabolism which will not be effected much by the weight of the drug. Rather, the substituents attached to the compound and its other chemical properties will have a greater effect.
Moreover, the excretion of smaller molecular weight drug will be a little quick. But this effect will not be much changed.
Good Luck
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3-aminopropanol is a degradation product of panthenol (active ingredient in many creams). it present in low concentrations, so sample of the cream would have a large amount of cream. so what is the best method to determine it quantitatively?
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Hello sir,
HPLC would be a preferable method for detection of 3-aminopropanol present in low concentrations. Furthermore Spectrofluorimetric method could also be applied for the same. Please find the references.
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i want to increase the dissolution profile of cefpodoxime proxetil FC tablets IP.
Medium: Glycine buffer pH 3
Ingredients used: Cefpodoxime proxetil (D90 NLT 50micron), Carmellose calcium, SLS, Lactose & Magnesium stearate.
Granulation: Direct compression
Disso limit: NLT 70% but we achieved only 65-70%
Kindly help us to increase the disso profile. 
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Dear Sir. Concerning your issue about how to increase the dissolution profile of cefpodoxime proxetil tablets. Cefpodoxime proxetil (CP) is third generation cephalosporin antibiotic and has poor aqueous solubility which has direct impact on bioavailability. Dissolution profile predicted that solid dispersion prepared with 1:4 % w/w CP and PEG 6000 by solvent evaporation has shown highest drug release. Powder blend of all formulations was evaluated for pre-compression parameters (FTIR, Hausner’s ratio, Carr’s index and angle of repose) and it was observed that all excipients were compatible with CP and has excellent flow properties. Dispersible tablets were prepared by direct compression method using different concentration (0, 2.5 and 5 % w/w) of croscarmellose sodium and were evaluated for drug content, weight variation, friability, dispersion time and in vitro drug release studies. Drug content was found to be more than 97 % for all prepared tablets whereas friability and weight variation were below 1 % and 5 % w/w respectively. Tablet formulations containing 5% w/w of croscarmellose sodium showed least dispersion time (2.51 minutes) and highest drug release 98.09 % in just 30 minutes which was better than marketed formulation (CEFOPROX) as well as pure drug. Additionally, the prepared tablets (CPGT 5%) have quick onset of action that may provide fast relief from infection and consequently improvised patient compliance. I think the following below links may help you in your analysis:
Thanks
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My aim is to prepare glyceryl monostearate based NLCs gel employing Carbopol 974 (0.5% to 1.5%) as a gelling agent. However, upon addition of NLCs (blank/drug loaded) either during or after the gel preparation leads to formation of cream rather than retaining its gelling structure. Methyl paraben (>0.5%) is also added to the gel as a preservative. Kindly suggest the any solution for the same.
Regards 
Deepinder Singh
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I recommend keeping a close focus on your pH as you formulate as Dignesh has pointed out. Inclusion of glycerol in the aqueous gel may also help to stabilize your gel behavior. I would recommend an experiment to assess the impact of various pH levels on viscosity and the impact of glycerol. When deciding on pH levels to test, consider the pH and salt composition of the physiological system that will be encountered upon administration.
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I had tried three times for detection of andrographolide in blood after oral adminstration. Standard in mobile and plasma is detected very well with mobilw phase methanol: water at 223nm with very good linearity i.e 0.99. Can any one help me?
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Thank you
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Hello Dear Colleagues,
I need your help. Our company has manufacturing chemical material (sodium hydroxide, sodium percarbonate, etc that has been used for detergent's raw material.). We give this products an expiry date as 2 yrs. After two yrs, we retest retained sample according to specification. We obtained result within specification. And we prepaerd new CoA and give retest date as 1 year. We did not give an expiry date, only retest date.
Is it applicable procedure or not?
Thanks in advance,
Umut BASTURK
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This probably depends somewhat on your customers needs and usage of the materials you sell and then also on your own stock levels (ie how much stock you still carry and want to be able to sell to customers a year after you manufacture it.
Expiry or retest dates are both valid ways to advise customers of material shelf life but the stated shelf life should be accompanied by storage condition instructions. (e.g. keep dry and store below 25oC)
If your purpose in retesting after two years is to be able to sell more material from an older manufacture lot to customers who are happy with a 1 year shelf life then what you describe is an applicable procedure.
Chemical suppliers that we deal with will not offer us, the customer, a new CoA for the material upon retest in their factory probably because they cannot be sure we have correctly stored the material.  Customers may be able to conduct their own material retest if they want to extend the shelf life of the material in their own business use.
If you accumulate data over time that justifies reissuing another 2 year expiry I would suggest that is probably something you should consider doing.  However, if 1 year shelf life is acceptable to most of your clients then a 1 year expiry or retest date would be acceptable.
Hope these thoughts help.
Kind regards, Colin
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I've made ibuprofen tablets containing a 1:1 ratio of ibuprofen (20mg) and PEG. I've drawn a calibration curve by diluting my stock solution (0.2mg/ml) with 100ml phosphate buffer to make solutions with concentrations 0.01mg/ml-0.02mg/ml and calculated their absorbances. I've drawn a calibration curve, how do I calculate drug content using the equation of the curve and what happens if drug content is less than 85%?
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Plot the data (more than three concentrations) in excel and make a chart (scatter type). Click on any data point inside, then right click, select add trendline, then check "display equation on chart". This equation is Y= mX + C. Where Y is the absorbance, m is slope, X is the conc of drug and C is intercept.  If you have absorbance of unknown conc, then it can be determined.
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Hi everybody.
I was trying to analyse Ivermectin in a pharmaceutical product, but when I ran the standard it does not appear any peak (I'm using the USP 39 method for ivermectin).
I tried to modify the column and the mobile phase but it didn't appear anyway.
So I decide to check if the ivermectine was disolving correctly in methanol by analysing its UV spectrum and I found that there was no the expected spectrum, instead I got a weird signal (I have attached a photo).
So my question is: could it mean that the standard has degraded? or probably it could be a UV lamp problem?
By the way, the sample looked like it has the ivermectin compared to other analysis from months ago  (obviously I cannot be sure unless I compare it with the standar).
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Yes. Your concentration is far too high. Absorbance > 3 is not valid at all. The strange peaks may be noise of the detector. Your spectrum needs to be below 2, better around 1. By the way, your methanol seems to be too dirty. You need a UV or HPLC grade quality. The signal of methanol should be very low in your wavelength range.
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I am working on liposomal products and have found some paper about octreotide liposomal and would like to know if any products exist.
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Hi,
Still not on the market.
For a list of liposomal drug products on the market have a look at this article:
Pharmaceutical liposomal drug delivery: a review of new delivery
systems and a look at the regulatory landscape.
Claudia Zylberberg and Sandro Matosevic
Drug Deliv, 2016; 23(9): 3319–3329.
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Dear all.
What is the justification of different dissolution medium for Loperamide hydrochloride capsule and loperamide hydrochloride tablet in USP, though both are oral solid dosage form?
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It is necessary to understand that what is selected for dissolution testing in the USP is somewhat arbitrary. It is not based on science p- it is based on the submissions to the FDA for product approval. The dissolution test is a long way away from actually being a biomimetic test procedure and that is why we find many methods in the USP that have no physiological logic behind them. In this case I would guess that the capsule and tablet were developed by different companies and therefore they were separate submissions to the FDA and, on the approval of the FDA submission, the USP has no alternative but to accept whatever was in the registration files.
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If the compound to be detected is being run in HPLC, is it necessary to prepare that particular compound with the mobile phase??
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No, it is not.  But it is to good practice to prepare the sample with mobile phase, the baseline will be cleanner.
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Hello everyone,I want to detect steroid drug substances that contamination in herbal medicine so I know the method for detect them.There are TLC(thin layer chromatography).It use 10% sodium hydroxide ,1%Tetrazplium blue and heat until appear purple dot.so,heat is complicated when detect on out side laboratory.
Thank you
Vitsarut Primpray
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 You can review and adapt this article.
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I want to analyze carbohydrates (starch, glycogen, and cellulose) using one of these machines. Our University has the P/ACE MDQ CE system but we have been working with a collaborator (in another country) who has the PA800 system. I want to know if I could do the analysis without always sending samples someplace else. 
Any suggestions are greatly appreciated.
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Hi Corey,
they are different generations of CE systems, sold by Beckman Coulter (now scixe). Tareq's answer above does not refer to the same system, as that one was adapted to mass specs. The PA800 is a standalone version. The differences between the systems are different features and controls, although they are similar. I suspect you will need to do some method develoipment to transfer the method, but it might be wise to see if there is a manual online at the Beckman site which would help
St John
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There are four FTIR graphs all of which has their caption on beneath namely Acyclovir (API), Methocel-K15M (Polymer), Ethocel Standard 45P (Polymer) and Physical mixture of these three compounds. I had made the physical mixture in accordance with my formulation where the amount of pure drug was 200 mg and the cumulative amount of other polymers were around 1100 mg. I don't have in depth knowledge about FTIR. So I will be pleased if anyone explain my issue in a simpler way. Side by side I will be happy to get some link of website or article from where I can get a basic idea of interpreting FTIR graphs in a shorter period of time and use them as reference.
Thanks in advance.
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In theory, if you recalculate the graph into absorbance (A instead of T) you can calculate the fourth spectrum out from the first three Amix=c1A1+c2A2+c3A3, where c is the concentration of the mix. Differences between the theoretical and experimental  spectra of mixtures should show you some interactions between functional groups (like H-bonds).  In practice it is very hard to do it. If you try to do it, expect to spend a lot of time with high chance of failure.  Your spectra 2 and 3 are weak, it is obvious you do not control the humidity in the lab, spectrum 4 has T>100% which shows you have problems with the baseline.  The best chance is to see  a sharp peak slightly shifting left or right.
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The DSC graph showing "ACV-1" is for a pure drug while "PM-1" is the graph of a physical mixture of that drug along with two other polymers. I had made the physical mixture in accordance with my formulation where the amount of pure drug was 200 mg and the cumulative amount of other polymers were around 1100 mg. I don't have in depth knowledge about DSC. So I will be pleased if anyone explain my issue in a simpler way. Side by side I will be happy to get some link of website or article from where I can get a basic idea of interpreting DSC graphs and use them as reference.
Thanks in advance.
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Hello,
First I would go to the website of the DSC manufacturer and look up how to process your data after the experiment (hopefully using their software). This will be best since it would involve the same software you used to obtain your data and you would not need to convert your data back and forth. From a first glance you need to do two major things (assuming you have not already done them):
1) Display your data in the same way. Have the same tranisitions (like crystallization peaks) pointing in the same direction on all graphs. This does not seem to be the case and it causes lots of confusion. I also normalize my heat flow (y-axis) by the mass of the sample so the integrals can be directly compared in terms of crystallinity, etc.
2) You should do a baseline subtraction. This could be as simple as running an empty sample pan and subtracting that data from what you have. This will flatten your baseline and hopefully remove any odd stuff NOT caused by your samples.
In addition, I would search if anyone has done DSC on your pure drug so you can see what the result should look like and compare it to yours. Hopefully this would put you in a better position to analyze your data. Good Luck.
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Dear all, I just came across with the efavirenz tablets dissolution test in USP (apparatus II, 50rpm; Medium: 2.0% (w/v) sodium lauryl sulfate in water; 1000ml) and it states “Do not deareate” the medium. I know that when using surfactants (and some buffers) the air bubble formation in the tablets surface (as well as in the paddle and vessel surfaces) does not occur in such an extent as to become critical. However, one thing is to state that there is no need to deareate and another is to state not to do it. So, any clue on the actual reason for USP stating to not deareate the dissolution medium?
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write directly to USP. for possible explaination
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Hi,
I'm preparing for studying the effect of some pharmaceutical excipient  on P-glycoprotein  function in intestinal brush border. Unfortunately, we had some technical problems during preparation of everted gut sacs. So, can we prepare gut sacs without eversion by placing the test solution inside the gut sacs? then samples were collected from the outside acceptor  compartment?
Thanks .
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Hi Khaled,
You can use gut sac without eversion, however eversion of gut sac helps in getting more volume in contact, because without eversion less volume of solution of drug/ excipients can be used, however in everted sac you can put it in a suitable container containing your desired amount of medium.  
Hope you find this answer helpful...
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Experimental results of IC 50 were calculated 3 times for each compound wich means we have got IC50 +/- error.
for QSAR modeling we used to take the pIC50 but for exact values of IC50 not like this time.
Please let me know is there a way how to fix values or to use theme as they are shown with the error +/- ?
Thank you in advance
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Yeah, one can avoid the uncertainty(i.e convert 10.80 into pic50 and leave the +/- 3.01). However, the best way is "not to incorporate the molecules whose activity is uncertain " This is only possible if one has enough number of active compounds otherwise stay with avoiding uncertainties. 
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when I reacted acridine with imidazole in toluene at 140 C  to get imidazolium salts, I got percipate means there was reaction happened ...bt when i checked H NMR only acridine peaks appear ? any suggestion why
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Acridine and imidazole would not react under those conditions.  Something is missing from your description.  (Perhaps you are using a 9-halogenated acridine?) 
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If the gelatin caps are stored in ware house for 1.5 year and they have expiry date of 3 years.then if they are used for product having expiry of two years how the gelatin caps will be used and what can be impact on the product?
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Provided the storage conditions are adequate and controlled and you already know that the shelf life of the drug product (i.e. capsules filled with excipients and drug substance) under certain conditions is 2 years, if you produce capsules with starting materials that are within each respective shelf life the shelf life of the drug product is, as you mention, 2 years.Of course what Ashish wrote is always valid.
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We have a Bruker Raman Spectrometer, what we have been using for solid opaque sample successfully. But, when it comes to liquid sample, even using Raman probe we are not getting any spectrum. Can anybody please help me by directing how to use liquid samples (both opaque and transparent) for getting Raman spectrum? Thanks in advance.
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This question is perfect for being answered by Bruker customer support, isn't it?
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How should I make a calibration curve for clarithromycin in water?
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Dear co- lerner,
Its very simple step, just make different dilution/serial dilution of clarithromycin in water and scan it in UV spectroscopy on 353 nm using water as blank. 
 you can follow these paper, 
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I found that almost all the applied cases related to  pharmaceutical analysis through UV spectroscopy obey beer's lambert law which is a linear problem. Is there any application in the pharmaceutical analysis field where non-linear models should be used rather than linear models in UV spectral data ? thanks 
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I've been preparing an oral dispersible film of Meclizine HCL (25 mg) that has to be solubilized in water. Unfortunately, it is almost insoluble in water (0.1 mg/ml). I tried using complexation method with cyclodextrins, solid dispersion method taking PEG 4000 as a carrier, used sodium citrate to shift the pH to an upper range so that drug ionization takes place aiding in enhanced solubility; however, the result has not been as promising as I would have liked. I would be grateful to get your inputs. Thank you.
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You can make trial by using surfactant micellization. Use some type of surfactants like Spans or Tweens to get your drug solubilized.
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I have a plant with interesting anti-diabetic activities (in vivo experiments) and i want to investigate the effect of some phytochemical constituents of this plant on diabetic enzymes (enzyme inhibition) 
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Dear Thamere, here you have some that we are working on: Amylase, glucosidase, dipeptidyl peptidase-4
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Is it possible to analyze only with HPLC. As far as I have read the literature, MS is required. Is there any alternative?
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ng/L if referred to as single ng/L from contaminated surface water or waste water by means of HPLC-DAD. not completely impossible but in reality not feasable.
as you need about 1 ng on column to get a reasonable signal from a DAD, you would need to extract a lot clean up terrifically and concentrate massively.
1 ng on column if injected 100 µL means 10 ng/ml  extract concentration as you need multiple injections you should probably have at least 500 µl extract volume. i.e. you need 5 ng total.
you need vigorous multistep clean (e.g. size exclusion and SPE on e.g. cyanopropyl SPE) up to remove as much matrix as possible.
to get 5 ng total you would need to extract 5 L of a water sample with 1 ng/L. The most critical is still the matrix and the clean up.
so you need to be VERY (very very very) good at clean ups, extractions and HPLC-DAD to get that done.
kind regards
Kai
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how to extract simvastatin from plasma to be detected by HPLC ?
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C18 SPE cartridge. Supelco has a published solution to this on their Web site.
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How can i break an amide bond to obtain a drug from its prodrug in in-vitro condition?
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Dear Paulami,
You may conduct hydrolysis in the presence of sodium hydroxide (a base) or a strong acid such as sulfuric acid.
For more on these conditions, please see the publication contained in the following link:
Or you may cleave the amide by amidase enzymes:
Hoping this will be helpful,
Rafik
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My drug conc. in sample is very poor (0.05%) ,but povidon conc. is high, UPLC analysis it giving large interference and wave baseline at lower nm , as other nano-meters i cannot use , so only way in front of me to remove it from sample using suitable methology.
Thanks in advance
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Dear Rahul,
You can use the following procedures to precipitate povidone if your drug is stable in the following conditions:
1-To 5 ml of a 1 in 50 solution of the sample add 5 ml of dilute hydrochloric
acid TS, 5 ml of water and 2 ml of 1 in 10 solution of potassium dichromate.
A yellow precipitate forms.
2-Add 5 ml of a 1 in 50 solution of the sample to 75 mg of cobalt nitrate and
0.3 g of ammonium thiocyanate dissolved in 2 ml of water, mix and acidify
with dilute hydrochloric acid TS. A pale blue precipitate forms. 
3-To 5 ml of a 1 in 50 solution of the sample add 1 ml of 25% hydrochloric
acid and 5 ml of 5% barium chloride solution and 1 ml of 5%
phosphomolybdotungstic acid solution. A voluminous white precipitate is
formed which becomes gradually blue on standing in daylight.
The precipitate should be filtered and the filtrate is to be injected into the UPLC.
For more information on povidone, please use the following link:
Hoping this will be helpful,
Rafik
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 before assaying phenolic acids such as rosmarinic acid, ferulic acid, caffeic acid, salvianolic acid, lithospermic acids and etc.  with HPLC 
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Dear Ghasem Esmaeili,
Please find the method for the determination of total phenols, and phenolic acid in my publication ( Food Measurement and Characterization).
Best regards
Aly R Abdel-moemin
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I have looking for the data on stability of Curcumin in water. Although, many studies show pH dependent stability of Curcumin, but i couldn't get any which shows stability in water. Specially how long it's stable in water as emulsion form. Can anybody please help me.
Thanks in advance. 
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Dear Mohammad,
The following link contains a recent kinetic study on curcumin in water at different pHs and in combination with organic solvents. Curcumin have should a first order kinetics when was studied in its free form:
AAPS J. 2016 May;18(3):777-87. doi: 10.1208/s12248-015-9863-0. Epub 2016 Apr 1.
A Kinetic Degradation Study of Curcumin in Its Free Form and Loaded in Polymeric Micelles.
Naksuriya O1,2, van Steenbergen MJ2, Torano JS3, Okonogi S4, Hennink WE5.
Author information
 
Abstract
Curcumin, a phenolic compound, possesses many pharmacological activities and is under clinical evaluation to treat different diseases. However, conflicting data about its stability have been reported. In this study, the kinetic degradation of curcumin from a natural curcuminoid mixture under various conditions (pH, temperature, and dielectric constant of the medium) was investigated. Moreover, the degradation of pure curcumin at some selected conditions was also determined. To fully solubilize curcumin and to prevent precipitation of curcumin that occurs when low concentrations of co-solvent are present, a 50:50 (v/v) aqueous buffer/methanol mixture was used as standard medium to study its degradation kinetics. The results showed that degradation of curcumin both as pure compound and present in the curcuminoid mixture followed first order kinetic reaction. It was further shown that an increasing pH, temperature, and dielectric constant of the medium resulted in an increase in the degradation rate. Curcumin showed rapid degradation due to autoxidation in aqueous buffer pH = 8.0 with a rate constant of 280 × 10(-3) h(-1), corresponding with a half-life (t1/2) of 2.5 h. Dioxygenated bicyclopentadione was identified as the final degradation product. Importantly, curcumin loaded as curcuminoid mixture in ω-methoxy poly (ethylene glycol)-b-(N-(2-benzoyloxypropyl) methacrylamide) (mPEG-HPMA-Bz) polymeric micelles and in Triton X-100 micelles was about 300-500 times more stable than in aqueous buffer. Therefore, loading of curcumin into polymeric micelles is a promising approach to stabilize this compound and develop formulations suitable for further pharmaceutical and clinical studies.
Hoping this will be helpful,
Rafik
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Hi there,
I could separate the R and S enantiomers of Baclofen successfully, but I have problem with "Chiral column" that should not be run with more than 15% of organic solvent. Avoiding organic solvent results in loosing the resolution of peaks. 
Does any body have an idea that how I can overcome ion suppression in LC/MS-MS without using organic solvent?
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You can increase the % of organic used to obtain better resolution with your Crownpak column, but the column's lifetime will be reduced. Sometimes this is a good trade off for creating a method that works, but only if it is reproducible and reliable.
Reducing the sample concentration can help with peak shape if you are overloading the column. If so, reduce the injection volume amt to reduce the load on the column (in general, chiral columns have very poor capacities).
Alternatively, try a different chiral method (column & mobile phase). Plenty of examples can be found on the web using a keyword search. *Crownpak columns are not well suited to this task.
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Should I use Non-Compartmental Analysis or Compartmental Analysis? If Compartmental analysis, should it be 1or2 compartment model and why?
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Dear Showande,
Recently the compartmental pharmacokinetic analysis has achieved the great height, now many computational systems are available that includes whole body and calculates you the pharmacokinetics of any drug as it like a human body. Systems are available that have as many as 18 or more physiological compartments in it. One of this PK-Sim of Bayer technology Services Gmbh. You can go to the link 
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K=0.0893,T50=5.115,Correlation coefficient =0.993 n=0.268
T50=5.115