Application of a high-enrichment microextraction approach for the extraction of polycyclic aromatic hydrocarbons in smoke-infused milled rice.

BACKGROUND: In this study, an efficient sample preparation method was developed for the extraction and preconcentration of selected polycyclic aromatic hydrocarbons from smoke-infused milled rice samples, using a homogeneous liquid-liquid microextraction technique. In a conical-bottom glass test tube, a standard solution of the target analytes was added, followed by a few microliters of 1,2-dibromoethane and toluene. The mixture was vortexed to form a homogeneous solution. Subsequently, sorbitol was introduced and the mixture was vortexed again, leading to phase separation. After centrifuging, the organic phase containing the extracted analytes was collected at the bottom of the tube. An aliquot of the organic phase was then injected into a gas chromatograph equipped with a flame ionization detector.

RESULTS: The method exhibited excellent analytical performance, with low detection limits (0.19-0.59 μg L-1), high enrichment factors (1358-2232), and good linearity (r2 = 0.9907-0.9988) of the calibration curves. Relative standard deviations were ≤15% for intra-day and inter-day precisions obtained at concentrations of 10, 25, and 100 μg L-1 of each analyte.

CONCLUSION: Phase homogeneity was disrupted using sorbitol for preconcentration of analytes. The aqueous solution of analytes was placed in a conical-bottom test tube, and 1,2-dibromoethane along with toluene were used to form a homogeneous phase. The method was simple, cost-effective, and environmentally friendly, and suitable for monitoring analytes in smoke-contaminated food matrices such as milled rice. © 2026 Society of Chemical Industry.