Abstract
A method was proposed for the electron-capture gas chromatographic determination of methyl parathion in rice grains. To 25 g of rice grains was added 50 ml of n-hexane. After allowing to stand at room temperature overnight, n-hexane was filtered through a glass filter (17G3), and the residue was washed several times with each 30 ml of ether. The eluate was evaporated to 10 ml, and cleaned up by the alumina column chromatography using n-hexane-ether (9 : 1) as developing solvent. An aliquot of the n-hexane solution was injected into a gas chromatograph with a spiral galss column, 5 feet × 1/8 inch (outside diameter), packed with 10% high vacuum silicone grease on 4060 mesh chromosorb W and an electron-capture detector. The column temperature was adjusted at 180°C. Nitrogen was used as a carrier gas, the flow rate being maintained to 20 ml per minute. Seventy to 101% of methyl parathion was recovered by this method from rice grains containing 0.1 to 10 ppm of the methyl parathion and Sumithion.
