**2.2.2 Qualitative analysis and quantitative analysis**

#### **2.2.2.1 The qualitative and quantitative analysis of PAH**

The GC-MS was calibrated with standard compounds of known concentrations at eight different concentrations: 0.2 ppm<sup>1</sup> , 0.4 ppm, 0.8 ppm, 1 ppm, 2 ppm, 4 ppm, 8 ppm, and 10 ppm. The calibration curves of 16 PAHs based on the average response factors were used for concentration determination. Target compounds were qualified using the internal standard technique. Their concentrations were reported as nanogram/gram (µg/g) based on dry sediment weight.

#### **2.2.2.2 The qualitative and quantitative analysis of aliphatic compositions**

The lack of standard compounds seems to bring difficulty to the qualitative and quantitative analysis of aliphatic composition, but the equally-spaced retention time makes it possible to determine the carbon number of aliphatic compositions properly once one of a series of samples was subject to GC-MS analysis. Because the response factors of aliphatic compositions with different carbon number are almost the same, the quantitative analysis was accomplished in accordance to the response factor of internal standard C20d42.
