Amr Hefnawy

7 Questions 1 Answers 0 Followers

Questions related from Amr Hefnawy

Waters 2707 HPLC autosampler problem?

I am using a 2707 waters HPLC device. When I try to inject a sample, it says missing plate or rack. I changed the needle and calibrated its position but I still get the same problem. I even get...

03 March 2021 2,219 1 View

Is it reliable to measure UV absorbance for a calibration curve at 207 nm? or would interference be too high at this short wavelength?

I need to have a calibration curve for Ribavirin which I found that its maximum absorbance is observed at 207 nm while most of the reported papers measure it at 250 nm

08 January 2019 7,970 1 View

What is the role of Triisopropylsilane during the cleavage of peptides from the resin using Solid Phase Synthesis?

During cleavage of peptide after solid phase synthesis ... cleavage is done using 1-5% TFA in methylene chlordie containing 5% triisopropylsilane. What is the role of the triisopropylsilane in...

04 January 2018 8,948 6 View

Why terminal groups in polymers do not appear on ATR-FTIR while they appear on FTIR instruments using KBr cells?

I have been working on a common reaction for the conversion of mPEG into mPEG-COOH. I used for the characterization ATR-FTIR that requires small amount of the powder sample (ThermoScientific...

06 February 2017 657 4 View

Is it possible to use clays as Zeolite for "intravenous" drug delivery systems?

Is there any data regarding the toxicity of clays as zeolite when used through the intravenous route? if there is known toxicity ... what is its mechanism?

28 March 2016 5,142 2 View

Is it possible to use DLS to determine the molecular weight of polymers? How would this be accurate? and what are the limitations?

I wanted to measure the molecular weight of alginate polymer, is it possible to be done using DLS measurement and if not, what would be the suitable method?

21 March 2016 6,528 8 View

What is the optimum count rate for accurate DLS measurement of chitosan nanoparticles?

I am using malvern Zetasizer for the measurement of chitosan nanoparticles loaded with drug.

25 November 2015 754 7 View