New gas chromatographic method for residue determination of dithiopyr in soil, wheat grain and straw

A gas chromatographic method has been developed for a new pyridine herbicide, dithiopyr, utilising an electron capture detector. The method makes use of a column (10 m x 0.534 mm I.D.; 1 microm film thickness) containing HP-1 with nitrogen as a carrier gas at a flow rate of 15 ml min(-1) at temperatures of 190, 210, 270 degrees C for oven, injector port and detector, respectively. Soil, wheat grain and straw samples fortified with dithiopyr were extracted with acetone-0.2 M HCl (95:5) and cleaned up by partitioning with hexane. The technique has a sensitivity of 0.05 microg ml(-1) and the recovery of dithiopyr from soil, wheat grain and straw ranged between 80 and 99%.