Preparation of 2H- and 3H-labeled phaseic acid and dihydrophaseic acid as standards for determination of abscisic acid metabolites in tomato fruit

There have been reports that the level of abscisic acid (ABA) increases during the cold storage of tomatoes. However, the important ABA metabolites, phaseic acid (PA) and dihydrophaseic acid (DPA) were never quantitatively determined in such a system. In order to obtain the labeled standards for quantitative determination of those compounds by GC-MS-SIM, we fed bean plants with 6,6,6-[2H3]-ABA (mean isotopic enrichment 60%) with addition of about 105 Bq per mg of [3H]-ABA. After 100 hours the plants were harvested and extracted with acetone. The extract were purified by solvent partitioning and, Prep-Sep amino column and on an HPLC C18 reverse phase column. Two major radioactive metabolites of ABA were obtained and identified by GC-MS as PA and DPA. Some results on the quantitation of ABA, PA and DPA in tomato fruit after cold storage will be presented