Application of the Microwave-Assisted Extraction and Dispersive Liquid-Liquid Microextraction for the Analysis of PAHs in Smoked Rice

Abstract

This study developed an analytical method based on microwave-assisted extraction (MAE) and dispersive liquid-liquid microextraction (DLLME) followed by high-performance liquid chromatography for the extraction and quantification of four polycyclic aromatic hydrocarbons in smoked rice. Benzo[a]pyrene (BaP), benzo[a] anthracene (BaA), benzo[b]fluoranthene (BbF), and chrysene were employed as model compounds, and smoked rice sample was spiked with them to assess the extraction procedure. Effective parameters controlling the performance of the microextraction process, including the nature and volume of hydrolysis, extracting and disperser solvents, microwave time, and pH, were optimized. Optimized conditions were as follows: a hydrolyzing solution volume of 10 mL with 50 % ethanol, a pH of 5, and extracting and disperser solvent volumes of 250 mu L and 1.2 mL, respectively. Satisfactory results were achieved when this method was applied to analyze the polycyclic aromatic hydrocarbons (PAHs) in smoked rice samples. The MAE-DLLME method followed by HPLC provided excellent enrichment factors (in the range of 258-307 for PAHs) and good repeatability (with a relative standard deviation between 3.68 and 7.47 %) for spiked smoked rice. The chromatographic peak area was linear with concentrations in the range of 0.2 to 100 ng mL(-1) and with correlation coefficients ranging from 0.996 to 0.998 and detection limits between 0.05 and 0.12 ng mL(-1). The recoveries of those compounds in smoked rice were from 87 to 98 %. A comparison of proposed method with previous methods demonstrated that it is a simple, highly selective and sensitive, rapid, and reliable sample pretreatment method that gives good enrichment factors and detection limits for determining PAHs from smoked rice.