Abdul Aziz Khalfan Al Bahri

8 Questions 5 Answers 0 Followers

Questions related from Abdul Aziz Khalfan Al Bahri

Does the concentration of analyte affect when adding mobile phase to the matrix (urine /blood) after extraction and prior LC-MS/MS?

in bio-fluid samples, we used to add mobile phase (mobile phase A, B, or mixture) to the sample after extraction and prior to LC-MS/MS Wondering, it does not affect the analyte concentration?!!!....

28 October 2023 10,055 2 View

Why some time drug screening results higher than conformation results and vice virsa?

In our daily drug analysis. We note sometimes the screening results are higher than the confirmation. For example, THC is in most time the screening concentration is higher than the confirmation....

13 December 2021 5,988 1 View

How to estimate the optimal volume of enzyme and buffer volume in enzymatic hydrolysis?

Dear all I am wondering how to estimate the optimal volume of enzyme and buffer volume in enzymatic hydrolysis. For example, if my enzyme is 150 KU/ml b-glucuronidase and want to develop an...

22 September 2021 4,589 1 View

Can we use blood or urine case samples to study matrix matching by standard additions?

I am trying to study the matrix effect by standard addition. From my reading, I found a standard addition method that is used to study ion suppression and enhancement. Aliquots of the case sample...

05 June 2021 3,332 1 View

Who is the volume of enzyme estimated?

We do use enzymatic hydrolysis in the extraction of abused drugs in blood and urine. For example, if I am using 150 kU/ml b-glucuronidase and the sample volume is 100 ul, what is the optimal...

17 November 2020 3,101 3 View

I could not confirm the THCA in urine?

To those who are interesting in toxicology, I have postmortem urine and blood samples, both are initially positive for THCA using EIA and ELISA techniques respectively. The THCA in blood has been...

05 May 2020 3,085 0 View

Why there is difference in instrumental uncertainties?

From my GC-MS and LC-MS/MS experience, the chemist of Agilent we deal with ecommends to set uncertainty during quantitation setup 20 while of Schmedizo recommends it to be 30 Any comment is...

30 March 2020 7,028 9 View

Calculation of alcohol percentage of unknown alcohol content beverage

Hi everyone I am wondering what is the easiest calculation of % alcohol percentage in beverage if I used GC-FID and the result is by mg/100ml unit I hope to see full calculation with example...

01 January 1970 6,649 0 View