Free AA analysis
Jacek_Mozdzanowski-1@sbphrd.com
Tue, 30 Nov 1999 10:05:46 -0500
Angela,
Analysis of a single free amino acid does not necessarily mean that you will
have only that one amino acid in your sample. If you do have only one amino
acid in the sample, than ion exchange type separation with the use of sodium
buffers will do. If your sample contains a mixture of free amino acids, sodium
buffers will not (most likely) give you the separation which you need. In such
a case standard protocol for separation of free amino acids by ion exchange
calls for lithium citrate buffers which provide good separation of approx. 50
common free amino acids and their metabolites. I still remember from my college
days (long time ago, when amino acid analysis was as popular (?) as mass spec is
now) that sample preparation depended on amino acid source (blood, urine,
tissues and so on). Proteins were removed by precipitation with trinitrophenol
or sulfosalicilic acid. Trinitrophenol had to be removed from samples prior to
analysis, sulfosalicylic acid could stay in samples. I am sure there are
hundreds of specific applications described in literature and in many cases
sodium buffers may be sufficient. But since I do not know details of your
project/problem I can only offer such a general thought.
Jacek Mozdzanowski
Analytical Sciences
SmithKline Beecham