QuЕChERS SAMPLE PREPARATION IN THE DETERMINATION OF PESTICIDES OF DIFFERENT CHEMICAL CLASSES BY HPLC
The method has been developed of simultaneous determination of active ingredients of different kinds of pesticides in biological tissues (fish liver) by applying HPLC with ultra-violet detection and the rapid method of QuEChERS sample preparation. We defined optimum volume and composition of the reagents for the extraction, time of centrifugation and ultrasound treatment, the origin and composition of sorbents that ensure maximum extraction of the substances studied and further cleanup of interfering substances. Acetonitrile was used as a solvent. The extraction was carried out in the presence of a buffering mixture - trisodium citrate dihydrate and disodium citrate hemihydrate. Bondesil PSA bulk sorbents (alkylated amine containing two amine functional groups - secondary and primary) and C18E (reversed-phase sorbent based on silica gel with grafted octadecylsilane groups were used to purify the extract from coextractable substances (fats, proteins, sugars, organic and fatty acids, pigments and other impurities). The degree of extraction of the analyzed active ingredients of pesticides from the liver of fish was 79%. The detectable pesticide concentrations ranged from 0,4 to 0,97 mg/kg. The relative standard deviation of the analysis results amounted to 0,01-0,14