TURBIDIMETRIC FLOW METHOD FOR THE ENANTIOMERIC DISCRIMINATION OF L-ASPARTIC AND D-ASPARTIC ACID

The proposed enantiomeric resolution of aspartic acid is based on the inhibition of the crystallization of L- and D-histidine. A flow-throug h system permits the turbidimetric multi-detection of the signal produ ced in the crystallization of histidine from a supersaturated solution , The presence of L- or D-aspartic acid delays the growth of L- Or D-h istidine crystals, respectively, the delay being proportional to the c oncentration of aspartic acid. Calibration graphs are linear down to 4 0 mg l(-1) of L- and D-aspartic acid, with a precision (repeatability, as RSD, n = 11) of 2.5%, The method was applied to the determination of L-aspartic acid in pharmaceutical preparations (spiked with D-aspar tic acid) and the resolution of a racemic sample of D,L-aspartic acid, The results obtained were consistent with the nominal contents.