GC Determination of Benzene Homologues in Methanol after Extraction with Carbon Disulfide and Backwashing with Water

A method of GC for the determination of 8 benzene homologues in methanol was proposed. The methanol sample (200.0 mL) was extracted with 5 mL of CS2 and 200 mL of water. After phase separation, 200 mL of the upper layer was poured out, and another portion of 200 mL of water was added to the lower layer of CS2, shaked for 3 min to perform the 1st back-washing, and the back-washing with water was repeated 2 times more in the same way. Finally, the CS2 layer was taken for GC analysis. DB-WAX capillary column was used for seperation, and hydrogen FID used for determination. Linear relationships between values of peak area and mass concentration of 8 benzene homologues were kept in the same range of 1.0-40 mg·L-1, with detection limits (3S/N) in the range of 0.25-0.45 μg·L-1. The proposed method was applied to the determination of benzene homologues in industrial methanol, and recovery was tested by standard addition method, giving values of recovery in the range of 96.9%-101% with RSD′s (n=10) in the range of 0.56%-2.5%.