An infrared spectrophotometric procedure was used for simultaneous determination of small amounts of sumithion and methylparathion in a mixture extracted from spinach and lettuce. Measurements of the strong absorption peaks at 10.3μfor sumithion and at 10.8μ for methylparathion permit the determination of about 1 p.p.m. of these insecticides with 50 g. of spinach or lettuce.
