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Clinical Chemistry, Vol 21, 838-843, Copyright © 1975 by the American Association for Clinical Chemistry
1 The Manhattan and South Bronx Kidney Centers and The
Bronx-Lebanon Hospital Center, Bronx, N. Y. 10456.
The Bronx-Lebanon Hospital Center, 1276 Fulton Ave., Bronx, N.Y. 10456.
We present a method for separating and measuring guanidino acids by gasliquid chromatography. Compared to ion-exchange techniques, this system is faster, more sensitive, requires smaller sample volumes, is independent of colorimetric reactions, and permits simultaneous determination of both amino and guanidino acids. N-Trifluoroacetyl-n-butyl esters are formed and then are separated by using a column containing a mixed silicone liquid phase coated on Chromosorb W-HP. Analytical recoveries from plasma ranged from 86 to 112% and were optimal when purification and derivatization were done without prior protein precipitation. Speculations as to the cause of this interference by protein include coprecipitation, protein-binding, and cyclization of the guanidines in the acids used for denaturation. Evidence presented suggests that all three occur: ultrafiltrability is diminished in the presence of protein and nuclear magnetic resonance demonstrates cyclization of some of these esters.
Submitted on January 9, 1975
Accepted on March 17, 1975
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