Fuad Al-Rimawi

11 Questions 8 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 2,627 12 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 2,589 5 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 2,599 8 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 1,540 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 8,161 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 2,073 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 9,620 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 4,325 15 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 8,749 11 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 7,468 9 View

Can we use Milliq water for HPLC?

Does it need filtration through 0.4 or 0.2 micrometer filters?

01 March 2014 2,833 12 View