Analysis of chlorophenoxy acids and other acidic contaminants in food crops.

Several chlorophenoxy acids and chlorinated phenols were determined by means of gas chromatography in contaminated samples of cereals. Extraction of plant matrix with acetone/water mixture followed by alkaline hydrolysis was proved to be suitable for isolation of both free and conjugated residues. The use of pentafluorobenzyl bromide for volatilization of analytes, despite of enhanced ECD response, cannot be recommended for routine analysis.

Determination of aryloxyphenoxypropanoic acid derivatives in crops treated with herbicidal sprays.

A reproducible and sensitive gas chromatographic method has been developed for the trace analysis of fluazifop-butyl, haloxyfop-ethoxyethyl and quizalofop-ethyl as well as their main metabolites (corresponding acids analysed after conversion to methyl esters) in some fruits and vegetables treated with herbicidal sprays. Comparable detection limits (0.01 mg/kg) were achieved when mass fragmentography and/or the electron capture detector were employed.

Gas chromatographic-mass spectrometric investigation of phenoxypropanoic acid derivatives possessing herbicidal activity.

Fluazifop-butyl, haloxyfop-ethoxyethyl and quizalofop-ethyl, active ingredients of new selective herbicidal preparations, as well as their metabolites converted in to corresponding methyl esters were separated on several gas chromatographic columns. Bromination of fluazifop esters increased significantly the response of the electron-capture detector. Electron impact mass spectra of all the compounds investigated were recorded, and characteristic ions suitable for selected ion monitoring are given.

Residues of clopyralide (3,6-dichloropicolinic acid) in strawberries and their changes.

Residues of clopyralide in strawberries treated with herbicide preparation Lontrel 300 were determined using gas chromatographic method. The decrease of clopyralide content during the processing of contaminated fruits was observed. The rate of decomposition of this compound in model solutions (held at 75 degrees C, pH 3.

The fate of ethylenebis(dithiocarbamate) fungicides during processing of contaminated apples.

A spectrophotometric method based on the liberation of carbon disulfide is suitable for the determination of ethylenebis(dithiocarbamate) (EBDC) residues on apples. Homogenization of samples before analysis initiates rapid breakdown of EBDC, resulting in low recoveries. Thermal conversion of mancozeb to ethylenethiourea (ETU) in the course of apple processing was investigated.