A hybrid technique for measuring the content of xenobiotics in wild and cultivated blueberries

Laboratory control requires testing of berry products for the content of residual amounts of mixtures of various xenobiotics: pesticides, polycyclic aromatic hydrocarbons. In this regard, the purpose of this study was to investigate the physicochemical conditions of extraction of xenobiotics from wild and cultivated blueberries and further chromatographic analysis of the obtained extracts. The leading approach to the development of a hybrid method of laboratory control of residual amounts of xenobiotics in berries is the construction of a theoretical model of the method and empirical studies of the proposed conditions of the method. The first stage of the study was sample preparation and extraction of xenobiotics. It was found that pesticides should be extracted from homogenized plant material, and for the extraction of polycyclic aromatic hydrocarbons, berries with an intact skin should be used. It was found that 1% acetonitrile solution of formic acid is a unified extractant of xenobiotics. The need for sequential chromatographic analysis of the obtained extracts by using high-performance liquid chromatography with a fluorescent detector, methods of high-performance liquid chromatography and gas chromatography with mass-selective detectors was substantiated. Approbation measurements showed that the limit of quantitative determination of residual quantities of pesticides is 0.01±0.001 mg/kg, and the limit of quantitative determination of polycyclic aromatic hydrocarbons is much lower and is 0.5±0.05 μg/kg. The hybrid technique allows detecting and measuring the content of xenobiotics in extracts of blueberry berries within 90 minutes. The working ranges for controlling pesticide content are from 1.0 mg/kg to 0.01 mg/kg, for polycyclic aromatic hydrocarbons – from 20 μg/kg to 0.5 μg/kg. The magnitude of the error of the quantitative analysis was estimated using the root-mean-square deviation from the mean (σ, %). The completeness of extraction of xenobiotics was established as a percentage (r, %) using a series of studies of model samples artificially enriched with xenobiotics. It was found that the measurement error of xenobiotic content does not exceed 20%, the value of analyte extraction is within 90-108%, the method is suitable for laboratory control. The developed hybrid method is of practical value for performing laboratory control of chemical compounds dangerous to human health