CONTINUOUS KINETIC METHOD FOR THE QUANTITATIVE RESOLUTION OF STRUCTURAL ISOMERS OF ARGININE AND ORNITHINE

A flow injection method for the determination of L-arginine and L-orni thine based on the inhibition of L-histidine crystallization was devel oped. The open-closed system used permits turbidimetric multidetection of the signal in the crystallization of L-histidine in the presence o f an organic solvent (2-propanol). The proposed method permits the sel ective determination of L-arginine (0.3-12 mg l(-1)) and L-ornithine ( 0.5-20 mg l(-1)) in the presence of their D-enantiomers and other L-am ino acids without the need for a prior separation. The relative standa rd deviation was ca. 2.3% (n = 11). Both amino acids were determined s atisfactorily in pharmaceutical preparations, and their recovery after addition to samples was 100 +/- 3%. The sampling frequency was 7 +/- 1 h(-1).