Methods using gas chromatography (GC) to determine Phosphamidon in crops have been developed. Phosphamidon was extracted from crops, using acetone; its analysis was determined by FPD-P after purification. Studies, performed at 0.025~1.5 ppm fortification levels, showed recovery between 90.2~101.0%. The limit of detection of Phosphamidon in orange pericarp tested was 0.02 ppm.