Recoveries of the 16 PAHs were tested by spiking samples with
mixed PAH standard solution and they ranged from 64.0% to 124.0% for
rice roots, from 57.0% to 115.0% for soil, from 60.0% to 120.0% for air,
and from 74.2% to 131.0% for water. The method detection limits were 0.85 (NAP) to 6.8 (BghiP) ng/ml for the extractants. All glassware was cleaned using an ultrasonic cleaner (Kunshan KQ-500B) and heated to 400 C for 6 h.