Complete automation of extraction, cleanup, and GLC determination of residue analysis of some important triazine herbicides in soils has been achieved. Manually sieved soil samples are continuously delivered to the system, which presents cleaned up extracts to an automated GLC injection system. Peak areas are calculated by a digital electronic integrator. The output of the integrator is connected to a teletype printer which generates both printed hard copy and a punched paper tape in standard ASCII code. This information is fed by a punchtape reader into a programmed Wang 700 desktop computer. Final analysis reports are printed by an attached typewriter. The system allows a 4-fold output of analytical results with half the personnel compared to manual analysis.
An analytical procedure is described for determination of residues of bromopropylate (BP) and its main degradation product 4,4'-dibromobenzophenone (BBP) in honey. The method also allows the determination of 4,4'-dibromobenzilic acid (BBA), a potential intermediate to BBP. The method involves dissolution of the honey in water and separation of BP and BBP from BBA on a partition column. BP and BBP are further cleaned up and separated on a silica gel column and determined by gas chromatography (GC) with electron capture (EC) detection. BBA is oxidized with potassium dichromate to BBP, which is partitioned into dichloromethane and further cleaned up on a silica gel column before determination by GC with EC detection. The method is sensitive to 0.02 mg BP or BBP/kg and 0.023 mg BBA/kg honey.
A gas chromatographic (GC) procedure is presented for the determination of residues of avilamycin and all its metabolites/conjugates which can be converted to the common moiety dichloroisoeverninic acid (DIA). The method involves alkaline hydrolysis to DIA, cleanup by partitioning with chloroform, acidification of the aqueous phase, and partitioning of DIA into methylene chloride. After methylation of DIA, the product, 3,5-dicMoro-4,6-dimethoxy-2-methylbenzoic acid methyl ester, is cleaned up on a silica gel column prior to the final determination by electron capture GC. The method is sensitive to 0.1 mg/kg avilamycin equivalent. Overall average recoveries were 85.4%, with a standard deviation of 9.1 % for n = 20. Analyses of feces, urine, tissues, and fat of pigs treated with avilamycin demonstrated that 93% of the administered substance is excreted in feces and urine, within 72 h after treatment, and that no residues (<0.1 mg/kg) can be found in the tissues and fat of the animals at any time between 0 and 7 days after treatment with medicated feed.
Complete mechanization of extraction and cleanup steps has been developed for atrazine residues in soils for analysis by nitrogen detector gas chromatography. Manually sieved and weighed soil samples are mechanically presented at a maximum rate of 6 per hour to this system, which delivers cleaned-up solvent extracts of the samples at the same rate to a fraction collector. Adjustment of final solvent volume in collection vessels and gas chromatography are performed manually in the present work. Atrazine residues in soils are thus rapidly determined down to a lower limit of 0.05 ppm.
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