CONTINUOUS-FLOW DISCRIMINATION OF L-HISTIDINE AND D-HISTIDINE

A continuous turbidimetric method for the sequential determination of L- and D-histidine is reported. The method is based on the decrease in the rate of crystal growth of L- and D-glutamic acid caused by the ad sorption of foreign species (L- or D-histidine, respectively) at speci fic point of the crystal surface. The method provides a limit of detec tion of 3 and 5 mg/l for Land D-histidine, and a relative standard dev iation of 3%. The high selectivity and sensitivity of crystal growth i nhibitory processes make them potentially useful for the enantiomeric resolution of inhibitory substances (e.g. L- and D-histidine). The pro posed method was applied to the determination of L- and D-histidine in synthetic samples, containing both enantiomers in variable concentrat ion ratios (from 1:1 to 1:30) with relative errors less than 3%. (C) 1 998 Elsevier Science B.V. All rights reserved.