CYCLIC AMINO-ACID DERIVATIVES IN GAS-CHROMATOGRAPHY

The basic protein amino acids, together with more than twenty other α-amino acids, were divided according to chemical similarity into characteristic groups and the particular mixtures were first condensed with 1,3-dichlorotetrafluoroacetone and, if necessary, treated with reactive anhydrides in a subsequent reaction step. The rate of condensation of 14C-labelled protein amino acids was followed by flat-bed chromatography. Approximately half of the tested compounds were converted into cyclic forms within a few minutes and analysed immediately. Amino acids with reactive side-chain groups were acylated in the condensation medium at room temperature instantaneously and subjected to analysis after a simple extraction procedure. The imidazolyl group of histidine was effectively blocked when, during extraction, a minute amount of chloroformate was added. Polyorganosiloxane phases coated on silanized supports of the usual particle size (80-100 mesh) enabled most of the derivatized amino acids to be determined. Analysis of diaminodicarboxylic acids, histidine and tryptophan required the use of larger support particles (45-60 mesh). © 1979.