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A recently published method involving the simultaneous extraction, gel permeation cleanup, and electron capture gas chromatographic detection of residues of the insecticide and acaricide chlorpyrifos and its principal metabolite 3,5,6-trichloro-2-pyridinol is successfully applied to Lorsban-treated peach and Bahia samples. Previous quantitation of these compounds has required 2 separate analytical procedures. Multilevel temperature programming and manipulation of the gel permeation column effluent rate are the only adjustments of experimental parameters necessary to avoid large amounts of gas chromatographic interferences. Chromatographic peaks are more clearly defined and easier to integrate with the multilevel program than they are with 2-step or linear programs. This is one reason that recovery data are improved over those reported for the method as applied in the pea vine work. Residue analysis conducted on field-treated peaches and Bahia grass show the newly published procedure to be sensitive and effective.

Three halogenated hydrocarbon compounds were applied to the surface of each of two .57 ha bluegrass plots in October. Each plot was stocked with 10 mature ewes 6 mo after application. Supplemental feed was not offered. Five ewes remained on the plots for 180 d, whereas the other five were removed and replaced at 60-d intervals. Average soil residues for the period of grazing were 13.3, 3.8, 29.3 and 32.8 mg/m2 HCB (hexachlorobenzene), DDE [1,1-dichloro-2,2-bi(p-chlorophenyl)ethylene], DDT [1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane] and PBB (polybrominated biphenyls), respectively, for plot 1 and 16.5 and 48.0 mg/m2 DDE and PBB, respectively, for plot 2. Average concentrations of residue in body fat of the five ewes grazing for 180 d were .37, .30 and .30 micrograms/g HCB, DDE and PBB, respectively, for plot 1 and 2.41 and .79 micrograms/g DDE and PBB, respectively, for plot 2. Average residue concentrations in ewes that grazed 60-d subperiods were nearly as great, which indicated that steady state residue levels were reached in less than 180 d. A second trial and was conducted 3 yr later after plowing and reseeding the plots, but only PBB was measured. Polybrominated biphenyl was distributed throughout the top 16 cm of soil but the quantity present had not changed appreciably from the first trial. After seven ewes/plot grazed 136 d, residues were detected in only one of the seven on plot 1, but were detected in all seven on plot 2 with an average concentration of only .032 micrograms/g. It is concluded that concentration of residue in body fat of ewes depended on the concentration of chemical at the soil surface and the amount of soil ingested.

Residue data from the 1972 (FY--73) National Soils Monitoring Program are summarized. Composite samples of agricultural soil and mature crops were collected from 1,483 of the 1,533 selected 4-hectare sites in 37 states. Analyses were performed for organochlorine and organophosphorus compounds, trifluralin and polychlorinated biphenyls (PCBs); analysis for atrazine was performed only when pesticide application data indicated current-year use. Organochlorine pesticides were detected in 45 percent of the soil samples. The most frequently detected compound was dieldrin, found in 27 percent of all soil samples. Other compounds detected, in order of frequency, included DDT, aldrin, chlordane, and heptachlor epoxide, found, respectively, in 21, 9, 8, and 7 percent of all soil samples. Crop samples were collected from 727 sites. All were analyzed for organochlorines; analyses were performed for organophosphates and atrazine only when pesticide application data indicated current-year use. For all crops, 40 percent of the samples contained detectable levels of organochlorines and 10 percent contained detectable levels of organophosphates. Atrazine was not detected.

In 1971 hay and soil samples were collected in 9 States to determine the incidence and levels of pesticide residues in hayfields. Residues were detected in 8 percent of the soil samples and 29 percent of the hay samples. DDT and its metabolites, DDE and TDE, were contained in 2 soil samples and 21 hay samples. Heptachlor epoxide and chlordane were detected in 1 soil sample, dieldrin in 5 soil samples, and diazinon in 4 hay samples.

Residue methodology is described for the determination of AC 217,300 residues in pasture grass and crop samples. After extraction and subsequent cleanup on an XAD-2 column, residues of AC 217,300 are determined by liquid chromatography (LC), using a reverse phase paired-ion chromatographic system and detection at 300 nm. The method has a validated limit of sensitivity of 0.05 ppm with corresponding control values for the commodities analyzed of less than 0.01 ppm. Apparent residues over 0.05 ppm can be confirmed by either gas chromatography with an electron capture detector (GC-EC) or gas chromatography-negative ion chemical ionization mass spectrometry (GC-NICI). The direct GC-NICI method circumvents the need for sample cleanup on the XAD-2 column, and offers a greatly simplified procedure that is useful for screening samples. Recoveries of AC 217,300 from the commodities analyzed have been satisfactory with all methods of analysis.