ANALYSIS OF 3-(N-OXALYL)-L-2,3-DIAMINOPROPANOIC ACID AND ITS ALPHA-ISOMER IN GRASS PEA (LATHYRUS-SATIVUS) BY CAPILLARY ZONE ELECTROPHORESIS

A method was developed for the simultaneous quantitative determination of the neurotoxic nonprotein amino acid 3-(N-oxalyl)-L-2,3-diaminopropanoic acid (beta-ODAP) and its nontoxic alpha-isomer 2-(N-oxalyl)-L-2,3-diaminopropanoic acid (alpha-ODAP) in seeds of grass pea (Lathyrus sativus) by capillary zone electrophoresis (CZE). Samples of 0.5 g of seed flour were extracted in 2 volumes of 10 mL of ethanol-water (6:4) by tumbling for 45 min each time. Hippuric acid was used as an internal standard. The separation was performed in a 50 mu m i.d. uncoated capillary at 515 V/cm and 40 degrees C in 20 mM Na2HPO4 buffer at pH 7.8 with direct UV detection at 195 nm. A linear response was recorded in the concentration range 0.015-1.8 mM. This corresponds to a detection limit of 0.1 g kg(-1). Comparison between the CZE method and a standard colorimetric method for measuring total ODAP in 38 lines of grass pea gave a coefficient of correlation of 0.994.