Optimization of conditions for the sample preparation using mathematical planning for determination of 1-hydroxypyrene in urine using method of gas chromatography-mass spectrometry

Abstract

Introduction. Biological monitoring of 1-hydroxypyrene is the most widely used method for evaluating the effects of PAHs on humans. The determination of 1-hydroxypyrene in urine is performed using gas chromatography-mass spectrometry (GC-MS). Material and methods. Sample preparation consists of extracting the analyte from the biological matrix by 2-fold liquid extraction with hexane, evaporation the extract to the dry residue in the nitrogen current, and re-dissolution of the dry residue in the silylating agent BSTFA. We used gas chromatograph Agilent 7890A with an HP-5MS capillary column and a mass-selective detector. 1-hydroxypyrene was identified as trimethyl silane on a mass chromatogram based on the retention time and intensity ratio of the registered ions. Results. Optimization of the conditions for liquid extraction of 1-hydroxypyrene was performed using mathematical planning, varying the mass of magnesium sulfate, the extraction time, and the extraction multiplicity. The planning matrix included eight experiments, and the degree extraction of 1-hydroxypyrene was used as an optimization parameter. Interpretation of the model showed the multiplicity of extraction to contribute more to the formation of the degree of extraction than the mass of magnesium sulfate and the extraction time. Discussion. The proposed method foк the sample preparation, based on the extraction of 1-hydroxypyrene by 2-fold liquid extraction with hexane for 2 min with the addition of 0.5 g of magnesium sulfate to the biological sample, allowed reaching the detection limit of 0.1 ng/ml. The evaluation of metrological characteristics showed RSD of the reproducibility to do not exceed 6.4%, the systematic error is not significant, and the accuracy index in the form of a total error is not higher than 15%. Levels of 1-hydroxypyrene in the urine of aluminum production workers are 53 - 414 times higher than in the control group. Conclusion. The choice of optimal conditions for liquid extraction of 1-hydroxypyrene by mathematical planning allowed developing a method for the determination this analyte in urine by GC-MS for biological monitoring.