DETERMINATION OF CARNOSINE AND OTHER BIOGENIC IMIDAZOLES IN EQUINE PLASMA BY ISOCRATIC REVERSED-PHASE ION-PAIR HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

The isocratic reversed-phase ion-pair high-performance liquid chromatographic technique presented provides a sensitive, rapid and reproducible analytical method for the selective determination of carnosine and other biogenic imidazoles in equine plasma. Plasma was deproteinized with 5-sulphosalicylic acid and the compounds of interest were isolated by sorbent extraction on Bond Elut PRS cartridges. Recoveries were 97-105% and the lowest limits of detection were 58.3 80.1 nM. All compounds of interest were well resolved within a maximum retention time of 9.2 min. The mean equine plasma carnosine level determined by this method was 11.31-mu-M. Comparative determinations were made in canine and human plasma. Carnosine was not detected in human plasma. Concentrations of imidazole in canine plasma are reported here for the first time.