Combination of high-performance liquid chromatography and microplate scintillation counting for crop and animal metabolism studies: A comparison with classical on-line and thin-layer chromatography radioactivity detection

Samples from crop or animal metabolism studies of pesticides were used to evaluate the performance of the combination of analytical or narrow-bore HPLC and microplate scintillation counting (TopCount). Samples with extreme matrix content such as grain and tomato extracts from crop metabolism studies as well as extracts from hen excreta or goat urine from farm animal metabolism studies could be injected, analyzed, and quantified directly without any sample pretreatment. The minimum amount of radioactivity injected was similar to1 Bq (60 dpm). Counting times from 5 to 60 min were used for detection and quantification. These results were compared with those from classical on-fine radioactivity detection and with radioactivity detection on thin-layer chromatography plates. The combination of analytical or narrow-bore HPLC and microplate scintillation counting (ropCount) offers high sensitivity and high resolution power at the same time. It could be clearly demonstrated that the combination of HPLC with microplate scintillation counting is superior to the classical on-line radioactivity detection and at least equivalent to the classical thin-layer radiochromatography regarding performance and sensitivity.