The PAHs were quantified using an external standard method.
The standard curve of each PAH was prepared by plotting the peak
area against standard concentration (ng/ml), and the amount of
each PAH was calculated on the basis of its respective calibration
curve. The limits of detection (LOD) and quantitation (LOQ) were
calculated by using the signal-to-noise ratio of S/N ¼ 3 and S/N ¼ 10,
respectively. The average LOD of 16 PAHs ranged from 0.005 to
0.36 mg/kg. The method recovery was determined by spiking the
samples with individual PAHs standards at three levels from 10 to
200 ng/ml in triplicate. Linear equations of the calibration curves
and recoveries of 16 PAHs are shown in Table 2. The regression
coefficient (R2) of the PAHs standard calibration curves covering the
concentrations from 5 to 200 ng/ml ranged from 0.9893 to 0.9998.
Average recoveries of 16 PAHs were in the range of 72e108%.