Simultaneous analysis of 25 pesticides in crops using gas chromatography and their identification by gas chromatography-mass spectrometry.

The simultaneous analysis of 25 pesticides in soy beans and rices was performed by gas chromatography with dual electron-capture detection and nitrogen-phosphorus detection. The pesticides were extracted from the samples with solvent and the Bio-Beads S-X3 clean-up procedure was used. Recovery studies were performed at the 1-ppm level of pesticides added to each crop. Their recoveries ranged between 83 and 105% with coefficient of variations of 0.5-8.2%. The gas chromatographic properties of the 25 pesticides were also investigated. Conformation analysis was achieved by the retention time and characteristic fragment ions using the technique of gas chromatography-mass spectrometry-selected-ion monitoring.