Medhat Emad

11 Questions 26 Answers 0 Followers

Questions related from Medhat Emad

What cause peak of l-lysine HCl to appear broad and how can i treat it?

I have a problem with l-lysine HCl peak in sample and standard as it appear with shoulder or broad.

05 May 2018 506 0 View

Can any one help me with an hplc UV method for determination of D-Sorbitol?

I am looking for a method to determine D-Sorbitol using hplc UV detector.any one can help

05 May 2018 9,021 7 View

What cause the sample and standard Peak to have a negative absorbance?

I have a problem in hplc analysis of L-cystine analysis that the peak of both sample and standard have negative absorbance. This the first trial . -UV detector at 500nm. -Mobile phase phosphate...

12 December 2017 8,080 2 View

In dissolution test for tablets, What kind of filters used to filter samples contain indigo carmine aluminum lake (E132) as colorant?

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...

08 August 2017 7,529 2 View

What is meant by HPLC grade water?

We have RO station produce purified water of conductivity less than 1.5µs/cm. will be any problem if i use it for HPLC analysis after filter it through 0.22 micron filter

01 January 2017 2,665 4 View

What cause shifting of retention time of a peak forward?

1- I have problem in shifting of retention time of a peak : During analysis of rebamipide, the peak of rebamipide shift forward. for example(Std at 20.0 and sample at 20.5), and as the sample set...

11 November 2016 1,441 10 View

What does it mean by about if it said in a monograph that the retention time is about 20?

In a monograph ,it said that the retention time of the peak is about 20.

11 November 2016 2,445 6 View

Why does the peak of one substance disappear when injecting a mix of two, but when I inject each substance alone separately, they both give peaks ?

mix consists of propylparaben as internal standard and glycyrrhizic acid, when i inject the mix only peak of internal std appear but when i inject each one alone each peak appear. using HPLC.my...

12 December 2014 9,925 13 View

How can I determine the shelf life (expiry date) of prepared volumetric solutions?

When I prepare a volumetric standard solution, I want to determine its expiry date by taking in consideration that it is not mentioned in any reference. And if possible I need a protocol for it.

04 April 2014 6,754 4 View

How to restore my column performance?

My column is Pico-Tag Column, 60Å, 4 µm, 3.9 mm X 150 mm used technique for HPLC amino acid analysis. Used in PicoTag® Amino Acid Analysis of Protein Hydrolysates.

01 January 2014 9,165 1 View

What is the official method for analysis of free amino acids by HPLC(WATERS)?

I need to know if this method is the official for analysis or not?

10 October 2013 6,895 5 View