Determination of pesticide residues by chromatographic methods for food safety

Abstract

The paper presents a methodology for the preparation of samples of oilseeds, lettuce leaves, apple fruits for the study of xenobiotics by chromatographic control of the following chemical groups of pesticides: benzimidazole derivatives, anilinopyrimidine derivatives, bipyridyl derivatives. The following processes are considered: homogenisation of the sample, purification of the extract by solid-phase or liquid-liquid extraction methods, obtaining of plant extract, and obtaining of analytes extract. For fine-grained homogenised samples of sunflower seeds, the optimal raw material-extractant ratio is 1:20, for paste-like homogenised samples of apple fruit – 1:10, and for liquid samples of homogenised lettuce – 1:5. Analysis of the distribution of xenobiotics parameter in the octane/water system (log Pow), reference data on dielectric constant and dipole moment of solvents allowed identifying extractants capable of dissolving and removing xenobiotics from raw materials. It has been found that a mixture of acetonitrile and methanol (4:1) should be used for the extraction of benzimidazole derivatives and anilinopyrimidine derivatives, bipyridyl derivatives are best extracted with methanolic trifluoroacetic acid (9.5:0.5). The content of xenobiotics in extracts obtained from samples artificially enriched with xenobiotics was quantitatively analysed. Xenobiotics were removed from samples of crop products containing traces of fat. The most difficult process of sample preparation is the process of extracting sunflower seeds. The content of xenobiotics in extracts obtained from samples artificially enriched with analytes is affected by the temperature at which the process takes place and the duration of extraction. Based on the chemical composition of the sample matrix and the list of analytes, the conditions of the variable component of the methodology are proposed: obtaining plant extracts under the action of selective solvents, homogenised raw material-solvent with constant stirring of the extraction system at a speed of 180-200 rpm, or when exposed to ultrasonic vibrations at a frequency of 37 kHz from 4 °C to 25 °C for 5-25 minutes. Control of the qualitative and quantitative composition of the studied plant extracts and extracts of analytes was studied by methods of high-performance liquid and gas chromatography (liquid and gas) with mass-selective detectors