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Cattle were fed chlorpyrifos daily for 30 days at levels of 3,10, 30, and 100 ppm. Muscle, liver, kidney, omental fat, renal fat, and subcutaneous fat were collected at the end of this period. In addition, omental fat was collected by biopsy at weekly intervals for 5 weeks following withdrawal of the highest level of 100 ppm chlorpyrifos. Residues of chlorpyrifos and its oxygen analogue were determined by thermionic or flame photometric gas chromatography. The 3,5,6-trichloro-2-pyridinol moiety as the trimethylsilyl derivative was determined by electron-capture gas chromatography. The procedures were used to quantitate chlorpyrifos and its oxygen analogue down to 0.01 ppm and 3,5,6-trichloro-2-pyridinol to 0.05 ppm. Residues of chlorpyrifos were mainly in the fat tissues and averaged 0.02 ppm (<0.01-0.05 ppm) with 3 ppm in the diet and 3.28 ppm (2.28-4.70 ppm) in fat of cattle fed 100 ppm. The 3,5,6trichloro-2-pyridinol was predominantly in the liver and kidney and averaged 0.20 ppm (0.16-0.23 ppm) in liver and 0.11 ppm (0.09-0.15 ppm) in kidney at 3 ppm; 2.41 ppm (2.16-2.61 ppm) in liver and 1.75 ppm (1.46-1.95 ppm) in kidney at the 100 ppm feeding level. No chlorpyrifos oxygen analogue was detected in any tissue at any feeding level.DURSBAN, trademark of The Dow Chemical Company

A method is described for the determination of residues of dinoseb (2-sec-butyl-4,6-dinitrophenol) in alfalfa, corn, cottonseed, field beans, almonds, peanuts, peas, potatoes, soybeans, grapes, oranges, peaches, pears, barley, wheat, and soil at levels ranging from 0.05 to 100 ppm. Dinoseb is first extracted by hot hydrolysis in methanol-sulfuric acid and subsequently partitioned into diethyl ether and adsorbed onto basic alumina. After elution with sodium bicarbonate, ether partition, and diazomethane methylation, the dinoseb methyl ether is adsorbed onto acidic alumina and eluted with ether. Electron-capture gas chromatography provides a sensitive means of quantifying residues of dinoseb down to 20 pg. Average recoveries ranged from 77 to 99%.

Freeze-dried samples of the morel mushroom (Morchella spp.) as well as other genera were hydrolyzed with hydrochloric acid and the free amino acids isolated by ion exchange chromatog-