Fuad Al-Rimawi

17 Questions 9 Answers 0 Followers

Questions related from Fuad Al-Rimawi

Can we use Milliq water for LC/MS?

Milliq water is used for HPLC with UV detection , but can it be used for LC/MS.

07 January 2018 2,640 12 View

What is the best method to determine 3-aminopropanol in a cream formulation?

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...

08 May 2017 1,956 2 View

How to get high resolution in cation exchange Liquid chromatography of two basic analytes?

In a separation of a basic drug analyte from its impurity using strong cation exchange chromatography (HPLC), using 150 mM of ammonium dihydrogen phosphate at pH 3 and flow of 1.4 ml/min, the...

24 January 2017 2,615 5 View

When is it better to use peak height in HPLC analysis instead of peak area?

Usually and in most cases peak area is used for analysis in HPLC, but in some methods (and also in few ones in USP) peak height is used. I am wondering if peak height can be used for HPLC analysis.

31 October 2016 1,143 15 View

What is the difference between Inertsil column and conventional columns in RP-HPLC?

In RP-LC there is a type of C18 column called Inertsil. Is there any difference between it and the conventional C18 columns in terms of separation, selectivity, resolution..etc.

02 September 2016 2,618 8 View

Is it possible to separate an analyte and its salt simultaneously by HPLC?

I am asking about the possibility of separation of an analyte like pseudophedrine and its salt pseudophedrine hydrochloride using HPLC simultaneously i.e using the same method? If it is not...

12 October 2015 286 7 View

What are the major compound-using phenyls that can be separated via stationary phase HPLC?

Phenyl is not widely used in reversed phase HPLC separation as C8 and C18 stationary phases. However it is used in certain cases (compounds), where C8 and C18 do not work.

01 July 2015 1,551 3 View

What are the main causes of retention time instability in reversed-phase analysis by HPLC?

In analysis of a weak acid with pKa of 4.6, using mobile phase of phosphate buffer pH 7.7 and methanol (63:37, v/v) and hypersil C18 column, the retention time of this analyte is not stable (it is...

21 May 2015 8,184 13 View

What is the antioxidant activity (FRAP and ABTS) of vitamin C as positive control compared to plant extracts.

Antioxiadant activities of plant extracts are measured using FRAP and ABTS assays, and usually vitamin C is used as positive control. The question is what is the antioxidant activity of Vitamin C?

18 February 2015 2,085 8 View

Do USP analytical methods need validation?

USP methods are usually validated and needs only system suitability test. But the question do really they need validation?

21 January 2015 9,718 3 View

Any tipps about TBARS method for lipid peroxidation quantification as malondialdehyde (MDA) by UV-visible spectrophotometry?

I am testing the potential of olive leaves extracts as natural antioxidants in food applications (meat products) by inclusion of different concentrations of olive leaves extracts in the meat...

04 August 2014 7,176 3 View

What is the minimum amount of a compound needed for proton and C13 NMR?

I am doing analyses of natural products using NMR andC13 NMR for fractions from plant extracts collected from preparative HPLC, but no signals appears in either proton NMR or C13 NMR.

03 August 2014 4,339 15 View

Any tips on derivatization of flavonoids by BSTFA and TMCS reagent for GC/MS?

I am doing derivatization of different flavonoids (Quercetin, morin, rutin, luteolin, apigenin-7- glucoside, luteolin-7-glucosie, catechin, taxifolin) using BSTFA and TMCS reagent (99:1 ratio)...

30 July 2014 3,022 3 View

How does one differentiate between two flavonoids (quercetin and morin) with the same chemical formula and molar mass using mass spectrometry?

Quercetin and morin have the same molecular formula (C15H10O7) and molar mass (302.2 g/mol). Quercetin is 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one while morin is...

07 July 2014 8,764 11 View

Which is more polar flavonoid: quercetin or morin?

Quercetin and morin have the same molecular formula (C15H10O7). Quercetin is 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one while morin is...

05 July 2014 4,165 2 View

What is the difference between specificity and selectivity of the HPLC method?

In method validation (ICH and USP) they use specificity of an HPLC method. Can we say that a validated HPLC method is specific for a particular analyte (e.g. pharmaceutical or impurity)? What I...

03 March 2014 7,491 9 View

Can we use Milliq water for HPLC?

Does it need filtration through 0.4 or 0.2 micrometer filters?

01 March 2014 2,849 12 View