Differences in the yields of polycyclic aromatic hydrocarbons by pressurized liquid extraction and the Japanese official method.

To improve the extraction of polycyclic aromatic hydrocarbons (PAHs) from sediment samples, we optimized the conditions of pressurized liquid extraction (PLE). The yields increased as the extraction temperature increased from 100 to 190 degrees C, but the effect of increasing pressure (from 15 to 20 MPa) was small. Parameters of 190 degrees C and 20 MPa, near the maximum of the equipment, gave the highest yield. Under these conditions, the yields of 17 PAHs were 1.5-34 times those obtained by the Japanese official method (shaking and ultrasonic extraction with acetone at room temperature).