Steven Schoenfeld

8 Questions 47 Answers 0 Followers

Questions related from Steven Schoenfeld

What is the best method for determining amino acids on HPLC C18 column DAD?

So I have a GC method with ethyl chloroformate that works for almost all amino acids except it doesn't do arginine, and serine and threonine smear badly due to the active hydroxyls. I tried OPA...

12 May 2022 9,433 4 View

Need a way to separate nucleotides from NaCl SPE?

I have been using capillary electrophoresis to quantitate I+G in flavors. The one problem I cannot seem to overcome is that I need my samples have less ionic strength than the CE running buffer or...

21 July 2021 1,810 4 View

What is causing Agilent G1600 EL 5207 CE pressure problem?

I am going crazy trying to figure out why I keep getting EL 5207 &5500 on my Agilent 1600 CE. I checked the buffer bottles they seem fine I get a pretty good pop when I undo the cap. The air...

01 March 2017 8,286 14 View

For NDA amino acids is there any substitute for cyanide?

I am interested in doing some of the amino acids on my CE that are troublesome or impossible using GC (arginine serine threonine). I am looking at the NDA protocol and the problem I see is the use...

14 July 2016 499 0 View

I anyone doing GC of amino acids using trifluoroacetylacetone and isobutyl or ethyl chloroformate?

http://www.omicsonline.org/open-access/gas-chromatographic-determination-of-amino-acids-and-polyamines-in-human-skin-samples-using-trifluoroacetylacetone-2157-7064.1000248.pdf I am attempting to...

12 August 2015 4,168 6 View

What is the best way to go about the capillary electrophoresis separation of very small peptides to get a size profile?

I am looking to get into CE (mainly because I don't have the budget for an HPLC). One of the things I am looking at doing is separating peptides by size. I have read about CGE mode but it seems...

18 March 2015 7,025 4 View

Derivatization and GC of nucleotides?

I would like to do disodium guanylate (GMP) and disodium inosinate (IMP) via GC. I have tried 6 different reagents and dozens of conditions and none has been successful despite publication...

14 November 2013 184 2 View

Silylation of Nucleotides for GC?

I would very much like to be able to do disodium inosinate (IMP) and disodium guanylate (GMP) via GC. So far I've tried the chloroformates, phenylboronic acid for the ribose diol and then the...

14 November 2013 1,518 0 View