Dispersive Liquid-Liquid Microextraction for HPLC-UV Determination of PAHs in Milk

A simple and rapid analytical method for the extraction and quantification of four polycyclic aromatic hydrocarbons in milk sample has been developed using dispersive liquid-liquid microextraction followed by the use of HPLC. Benzo(a)pyrene, benzo(a)anthracene, and benzo(b)fluoranthene were used as model compounds; the milk sample was spiked with these compounds to assess the extraction procedure. Experimental parameters that influence the extraction efficiency, including the nature and volume of the disperser and extraction solvents, pH, and the volume of milk sample, were optimized. Under the optimum extraction conditions (extraction solvent: chloroform, 200 μL; dispersive solvent: acetonitrile, 700 μL; and extraction time 5 s or less), the performance of the proposed method was evaluated. The chromatographic peak area was linear with concentrations in the range of 0.2-10 ng/mL(-1) and with correlation coefficients ranging from 0.9968 to 0.9985. The LODs, based on a S/N ratio of 3, ranged from 0.06 to 0.18 ng/mL(-1). The RSDs varied from 3.68 to 9.7% (n = 3). The recoveries of these compounds were from 88.38 to 100%. The performance of the present method was evaluated for the determination of polycyclic aromatic hydrocarbons in various types of milk samples.