ORGANOPHOSPHORUS COMPOUNDS BY GAS CHROMA

Method 8141 provides gas chromatographic conditions for the determination of part per billion concentrations of organophosphorus compounds. Prior to the use of this method, a measured volume or weight of sample (approximately 1 L for liquids, 2 to 30 g for solids) is extracted using the appropriate matrix-specific sample extraction technique. 2.1.1 Aqueous samples may be extracted at neutral pH with methylene chloride using either Method 3510 (separatory funnel), Method 3520 (continuous liquid-liquid extraction), Method 3535 (solid-phase extraction), or other appropriate technique. 2.1.2 Solid samples may be extracted with hexane-acetone (1:1) or methylene chloride-acetone (1:1) using Method 3540 (Soxhlet extraction), Method 3541 (automated Soxhlet extraction), Method 3545 (pressurized fluid extraction), Method 3546 (microwave extraction), Method 3550 (ultrasonic extraction), or other appropriate technique. 2.2 A variety of cleanup steps may be applied to the extract, depending on the nature of the matrix interferences and the target analytes. Suggested cleanups include alumina (Method 3610), Florisil (Method 3620), silica gel (Method 3630), gel permeation chromatography (Method 3640), and sulfur (Method 3660). 2.3 After cleanup, the extract is analyzed by injecting a measured aliquot into a gas chromatograph with either a narrow-bore or wide-bore fused-silica capillary column, and either a flame photometric detector (FPD) or a nitrogen-phosphorus detector (NPD).