A selective, easy-to-implement, express method for the simultaneous determination of amitraz and its metabolites residual content in honey in the range of analytes mass fraction from 25 to 250 μg/kg has been developed and validated. The technique is based on the analytes liquid-liquid extraction with dichloromethane from alkalized aqueous solutions of honey to improve the stability of the acid-labile insecticide during sample preparation. The resulting extracts are sufficiently pure and do not require additional purification using solid-phase extraction or its variants. The extractant choice is based on a preliminary study of amitraz, DMFF, DMF and DMA distribution in water-organic solvent (n-hexane, toluene, dichloromethane, chloroform) extraction systems. Quantitative determination is carried out with HPLC–MS/MS in multiple reactions monitoring mode using matrix calibration in the range of the mass fraction of analytes in honey from 25 to 250 µg/kg. Depending on the analyte, the values of the detection limit ranged from 0.2 to 2.3 µg/kg, the limit of determination was from 0.6 to 4.6 µg/kg, the relative standard deviation of the repeatability – from 1.4 to 5.8 %, relative standard deviation of intermediate precision – from 1.4 to 7.7 %, relative expanded uncertainty – from 9 to 22 %. Calibration graphs were linear in the range from 25 to 250 µg/kg. The instrumental limits of detection and determination, the matrix effect, the degree of extraction, the overall efficiency of the process, and the bias were also evaluated in the course of the validation process.

The distribution constants of amitraz and its three main metabolites (DMFF, DMF, DMA) for water–organic solvent (n-hexane, toluene, dichloromethane, chloroform) extraction systems were estimated. Based on the analysis of the substances distribution in the studied systems, it was established that dichloromethane is the optimal choice for amitraz and its metabolites liquid-liquid extraction for method development for their simultaneous determination in honey. Amitraz stability study in water-acetonitrile solutions with various additives demonstrated that 50 mM ammonia solution in water– acetonitrile mixture (1 : 1, vol.) should be used as solvent for the samples final solutions.

Method for determination of the insecticide amitraz residual content in honey has been developed and validated. The method is selective, express and easy-to-perform. The technique is based on the extraction of amitraz from alkalized aqueous solutions of honey with n-hexane and quantitative determination by high-performance liquid chromatography with mass spectrometric detection. Validation was performed using three types of honey at three levels of amitraz application 6, 120 and 220 µg/kg. The limit of quantification was 0.9 µg/kg, the calibration curves were linear in the concentration range from 2.5 to 125.0 ng/mL (the corresponding analyte content in honey is from 5.0 to 250.0 µg/kg), relative values of the standard deviations of repeatability and within-laboratory reproducibility did not exceed 3.4 and 5.9 %, respectively, the bias values varied from –8.2 to 5.6 %, the expanded uncertainty estimates of the results ranged from 12 to 16 % (P = 0.95). Instrumental limit of quantification, overall efficiency of the process and robustness were also evaluated during the validation process.

The distribution of six acid-type penicillins (penicillin G, penicillin V, oxacillin, cloxacillin, nafcillin, dicloxacillin) in the extraction systems of chloroform–aqueous solutions of ammonium sulfate was studied. The reported distribution coefficients values of penicillins demonstrated the effectiveness of using ammonium sulfate as a salting-out agent. Based on the data obtained, a procedure for milk sample preparation was developed for the quantification of the residual content of six acid-type penicillins.

. Extraction of six acid type penicillins (penicillin G, penicillin V, oxacillin, cloxacillin, nafcillin, dicloxacillin) from their water solutions by polar organic solvents ( n -hexane, toluene, chloroform, isoamyl alcohol) was studied. Penicillins were quantified by high performance liquid chromatography-mass spectrometry. The penicillins distribution constants were calculated. А possibility of developing a fast, effective and inexpensive method for the determination of trace amounts of acid type penicillins in foodstuffs using extraction by chloroform was shown.

A standardized procedure is developed for the determination of chloramphenicol in food products of animal origin of different groups using HPLC with tandem mass spectrometric detection with a limit of detection of 0.2 µg/kg. The extraction of chloramphenicol from aqueous solutions with organic solvents was studied. Optimized procedures for the extraction of chloramphenicol, purification of the extracts, and preconcentration of the analyte and the use of the deuterated form of chloramphenicol ensure quantitative determination using an external calibration method with an internal standard with the maximum expanded uncertainty of the results 18.4%.

Разработана методика одновременного определения остаточного содержания восьми антибиотиков группы пенициллина в продукции животного происхождения методом высокоэффективной жидкостной хроматографии с масс-спектрометрическим детектированием. Выделение аналитов из пищевой матрицы включает жидкостную экстракцию смесью воды и ацетонитрила, очистку от липидов гексаном и твердофазную экстракцию. Разделение определяемых соединений проводят на обращеннофазной колонке в режиме градиентного элюирования, количественное определение - по матричной калибровке методом внутреннего стандарта. Диапазон определяемых концентраций для каждого пенициллина в молоке и молочной продукции - от 2 до 100 мкг/кг, в мясе и мясных продуктах - от 10 до 800 мкг/кг. Abstract - A procedure for simultaneous determination of residual content of eight penicillin group antibiotics in foodstuffs of animal origin using high-performance liquid chromatography-mass spectrometry method was developed. The procedure involves liquid solvent extraction of target analytes from food matrix with the use of water-acetonitrile mixture, purification from lipids with hexane followed by solid phase extraction. The analytes were separated on reversed-phase column using gradient elution mode. Quantification of analytes was performed by the internal standard method with matrix-matched curves. The range of determined concentrations for each penicillin type varied from 2 to 100 mkg/kg for milk and dairy products, and from 10 to 800 mkg/kg for meat and meat products.