A gas chromatographic method using a capillary column is described for the determination of total amitraz residue in honey samples. The method consists of a preliminary extraction of the sample, an alkaline hydrolysis, an extraction of the 2, 4‐dimethylaniline formed, without the aid of steam distillation/continuous extraction, its derivatisation with heptafluorobutyric anhydride and a gas chromatographic determination using an electron capture detector. The method is very rapid and can be carried out in a test tube. The detection limit is 0.020 mg kg−1 and recoveries are of the order of 85%.
A method is described for the simultaneous determination of residues of five fungicides used for foliar treatment of apple and pear trees, and for postharvest application. After extraction, the mixture of these fungicides is cleaned‐up on a ‘SEP PAK C18’ cartridge and the components determined by gas‐liquid chromatography with electron‐capture detection. The minimum detectable amounts in apples and pears, on a fresh weight basis, were 0.005mg kg−1 for vinclozolin, 0.010mg kg−1 for captan, folpet and iprodione, and 0.020 mg kg−1 for captafol. The percentage recovery for each fungicide (calculated by analysing four samples of untreated apples and pears, to which varying concentrations of each active ingredient had been added) varied for vinclozolin between 70.0 and 89.2, for captan between 72.0 and 83.8, for folpet between 73.0 and 93.0, for captafol between 70.8 and 91.8, and for iprodione between 75.1 and 97.1.
An HPTLC method for determining fluorimetrically the residues of coumaphos in honey samples is described. The active ingredient is solid phase extracted with a C‐18 disposable column and determined densitometrically on HPTLC pre‐coated silica plates. The method does not require additional clean‐up steps, is extremely quick and can easily be adapted to routine determinations of a large number of samples. The determination limit is 0‐01 mg kg−1 and recoveries are above 87%.
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