REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC METHOD FOR THE DETERMINATION OF SOIL-BOUND [C-14] ATRAZINE AND ITS RADIOLABELED METABOLITES IN A SOIL METABOLISM STUDY

A rapid and simple reversed-phase high-performance liquid chromatography (RP-HPLC) method has been developed to determine [14C]atrazine and its radiolabeled degradation products using radioisotope detection and liquid scintillation counting quantitation. A 25 cm × 4.6 mm, 5-μm octadecylsilane (C18) column was used with gradient elution of acetonitrile and 0.01 M monobasic potassium phosphate (pH 2.0). The mobile phase was delivered at 1.0 ml/min. Fractions of the HPLC eluate were collected and the radioactive peak were quantitated as percent of the total radioactivity injected into the chromatographic system. A histogram of radioactivity (dpm) versus fraction number was constructed. Identification of individual radioactive peaks was conducted by comparing the retention time of the peaks in the histogram with the retention time of the peaks of non-radiolabeled standards obtained by ultraviolet detection at 230 nm. This method was applied to determine the degradation products of [14C]atrazine in a soil metabolism study. Four degradation products in the soil metabolism study were positively identified by co-chromatography technique. The limit of detection of the method for [14C]atrazine and its degradation products was 5 ng/ml for a 100-μl injection volume and when [14C]atrazine had a specific activity of 7.62 · 105 Bq/mg. © 1990.