A comparative study of the O‐phthalaldehyde method for the neurotoxin 3‐N‐oxalyl‐l‐2,3‐diaminopropanoic acid as modified by various laboratories

Abstract

The optimization of the quantitative photometric estimation of the neurotoxin 3‐N‐oxalyl‐L‐2,3‐diaminopropanoic acid (ODAP) after hydrolysis and reaction with o‐phthalaldehyde (OPT) reagent is described. Six modifications of the OPT procedure (as practiced in different laboratories) and the original Rao method were compared in estimating the ODAP content 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 observed with the procedure of the Agriculture Canada Research Station, Mordsen, Manitoba, Canada (Campbell method). The use of 0.5 M tetraborate as buffer further significantly improves the reproducibility. The Campbell modification includes a number of controls which reduce variation. The present study recommends the Campbell modification of the OPT method but with tetraborate buffer as standard procedure for the screening of the toxicity of L. sativus cultivars.

Linking a rapid throughput plate-assay with high-sensitivity stable-isotope label LCMS quantification permits the identification and characterisation of low β-L-ODAP grass pea lines

“…Development of low-β-L-ODAP varieties or β-L-ODAP-free varieties has been held back by a lack of appropriate assays to screen large populations of grass pea accessions or mutants. The first assay developed to measure ODAP relied on a spectrophotometric method [22] which was later adapted by many other researchers [23, 24]. This assay is the most widely used [25–28] because of its low setup and running costs but lacks sensitivity and specificity.…”

“…The second aliquot was reacted, in parallel, directly with the Rao reagents to provide a non-hydrolysed ‘background’ reading that was then subtracted from that of the hydrolysed extract. This removed noise due to substances other than ODAP resulting in absorbance at 420 nm [24]. The absorbances of the wells in the two plates were measured using a plate-reader spectrophotometer and the ODAP content quantified according to the calculation shown in the Methods section.…”

Determination of β‐N‐oxalyl‐l‐α,β‐diaminopropionic acid and homoarginine in Lathyrus sativus and Lathyrus cicera by capillary zone electrophoresis

“…For all the above, the determination and quantification of both compounds in Lathyrus seeds are very important from the point of view of human and animal nutrition. Different methodologies have been used so far to quantify these compounds . However, the most selective and rapid methodology for the determination of these two compounds is capillary zone electrophoresis (CZE).…”

Development of an Amperometric Biosensor for β‐N‐Oxalyl‐L‐α,β‐Diaminopropionic Acid (β‐ODAP)

“…Despite numerous modifications reported it is practically not selective towards the b-isomer because the a-compound also hydrolyzes to DAP. It is also non-reproducible and time consuming [13].…”