Determination of polycyclic aromatic hydrocarbons in milk samples by high-performance liquid chromatography with fluorescence detection

This paper describes a high-performance liquid chromatographic (HPLC) method for the determination of polycyclic aromatic hydrocarbons (PAHs) in milk samples. The method involves a liquid-liquid extraction procedure after saponification of milk samples with sodium hydroxide. Reproducible determination with highly sensitive detection was attained by HPLC with fluorescence detection using 1,2-bis(9-anthryl)ethane as an internal standard. The detection limits of 12 kinds of PAHs ranged from 1.3 to 76 ng/kg milk at a signal/noise ratio of 3. By the proposed method, the presence of 12 and 11 kinds of PAHs could be confirmed in commercial milk and human milk samples, respectively. The average concentrations of total PAHs (mean+/-SD, micro g/kg) were found to be 0.99+/-0.37 for commercial milk (n=14), 2.01+/-0.30 for infant formula (n=3) and 0.75+/-0.47 for human milk (n=51). High correlation coefficients between the concentrations of total PAHs and triglyceride were observed for commercial milk (r=0.659) and human milk (r=0.645).