Rapid preparation of micro sample and gas-liquid chromatographic determination of methoxychlor residues in animal tissues and water.

Methods are described for analyses of methoxychlor (2,2-bis(p-methoxyphenyl)-1,1,1-trichloroethane) in tissues of fish and invertebrate animals and in water samples. These micro methods offer economy in solvents and materials, and reduce health and fire hazards. Furthermore, the methods sufficiently reduce sample weights to allow analyses of small animals (mayflies) or animal organs. Samples are extracted in a ball-mill with n-hexane, and lipids are removed from fatty samples by freezeout. Small Florisil columns give final lipid cleanup and partial separation of methoxychlor from interfering materials. Methoxychlor is determined on a short gas-liquid chromatographic column (retention time 2.2 min). Animal tissue samples as small as 0.1 g and water samples of 5 ml can be analyzed at sensitivities of 10 and 1 ppb, respectively. Methoxychlor recoveries were 84-101% (fish and crab tissue), 92-100% (cod liver oil), and 98-107% (water) over a concentration range of 0.-10 ppm. Results obtained for fish tissue by using micro procedures agreed to within 20% of results reported by an independent laboratory using an established method.