A COMPARATIVE-STUDY OF THE 0-PHTHALALDEHYDE METHOD FOR THE NEUROTOXIN3-N-OXALYL-L-2,3-DIAMINOPROPANOIC ACID AS MODIFIED BY VARIOUS LABORATORIES

The optimization of the quantitative photometric estimation of the neu rotoxin 3-N-oxalyl-L-2,3-diaminopropanoic acid (ODAP) after hydrolysis and reaction with o-phthaladehyde (OPT) reagent is described. Six mod ifications of the OPT procedure (as practiced in different laboratorie s) and the original Rao method were compared in estimating the ODAP co ntent of two cultivars of Lathyrus sativus. Considerable variation in the ODAP content of the same sample was observed even when determined by the same procedure in some cases. The desired reproducibility was o bserved with the procedure of the Agriculture Canada Research Station, Mordsen, Manitoba, Canada (Campbell method). The use of 0.5 M tetrabo rate as buffer further significantly improves the reproducibility. The Campbell modification includes a number of controls which reduce vari ation. The present study recommends the Campbell modification of the O PT method but with tetraborate buffer as standard procedure for the sc reening of the toxicity of L. sativus cultivars.