Gas-liquid chromatographic determination of captan and two metabolites in milk and meat.

A gas-liquid chromatographic (GLC) method has been developed for the determination of captan (N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide) and 2 metabolites, tetra-hydrophthalimide (THPI) and tetrahydrophthalamic acid (THPMA), in milk and meat. The sample is extracted with ethyl acetate and is cleaned up by acetonitrile partition and silica gel chromatography where captan, THPI, and THPMA are separated. Captan is directly determined by GLC. THPI and THPMA are separately derivatized in an acetone solution of pentafluorobenzyl bromide. The resultant derivatives are purified separately on an Al2O3 column and quantitated by GLC, using an electron capture detector. Recoveries from milk samples fortified at 0.02-10 ppm ranged from 71 to 102%; recoveries from meat samples fortified at 0.04-10 ppm ranged from 75 to 99%.

Residues in broiler chick tissues from low level feedings of seven chlorinated hydrocarbon insecticides.

Two chlorinated insecticide feeding studies from 1967-1968, using broiler chicks, have been completed. In Study I, lindane, heptachlor epoxide, dieldrin, endrin, methoxychlor, and DDT were fed in combination at 3 levels: 0.05, 0.15, and 0.45 ppm. Data show that, in fat tissues, heptachlor epoxide attained a level approximately 20 times the respective levels in the feed; dieldrin 15 times; endrin 10 times; p,p'-DDT 9 times; lindane 3 times; and o.p'-DDT less than the feeding levels. Of the DDT metabolites, p.p'-DDE and p,p'-DDD, only p,p'-DDE was significant at 3 times the 0.45 ppm feeding level. Endrin ketone, a metabolite of endrin, reached plateau levels approximately equal to feeding levels. All residue levels in liver tissues were less than 0.02 ppm. In Study II, technical chlordane was fed singly at the 0.05, 0.15, and 0.45 ppm levels. Results are tabulated for both total chlordane and for 6 identifiable isomers. Total chlordane in fat tissues attained plateau levels 3-5 times the respective feeding levels. Total chlordane levels in liver and breast tissues were all less than 0.01 ppm.

Gas-liquid chromatography and liquid chromatography of ethylenethiourea in fresh vegetable crops, fruits, milk, and cooked foods.

The Onley-Yip procedure for determining ethylenethiourea (ETU) in milk and crops was modified to reduce interferences by the ethylenebisdithiocarbamates (EBDCs). A 20 g crop-methanol extract is cleaned up by adsorbing the sample onto Gas-Chrom S. desorbing ETU, and eluting ETU from aluminum oxide with chloroform containing ethanol. ETU is converted to the S-butyl derivative for gas-liquid chromatography (GLC) and flame photometric detection (sulfur mode). For liquid chromatography (LC), ETU is cleaned up on another aluminum oxide column and injected directly. LC and GLC results are confirmed by thin layer chromatography. A cooking procedure based on conversion of EBDCs to ETU is included for surveying crops for possible EBDC content. Recoveries from 8 crops and milk fortified at 0.05 ppm ETU ranged from 73 to 100%.