EFFECT OF HYDROGEN REARRANGEMENT ON THE DETERMINATION OF THE ENRICHMENT OF [N-15]LEUCINE BY GC/MS

摘要

In the determination of the enrichment of [N-15]leucine by GC/MS, the measured ratio of N-15/14-labeled leucine may be affected by H rearrangement, This effect was investigated using 11 esters of N-15-labeled and nonlabeled N-(heptafluorobutyryl)leucine. The H rearrangement is dependent on the nature of the alcohol used for the esterification. The labeling ratio increases with the length of the alkyl chain of the ester and with the number of the H atoms at the beta-site and, to a lesser extent, at the gamma-site on this chain. For the measurement of the enrichment of [N-15]leucine, better standard curves were obtained when ion fragments not affected by H rearrangement were used. [References: 9]