Objective:To establish a GC method for the determination of metacresol. Methods:The separation was performed on an Agilent DB-225 MS column (30 m × 0. 25 mm,0. 25 μm). The initial column temperature was set at 90℃,maintained 10 min, raised to120℃ with a rate of 2℃·min-1 ,and then raised to 150℃ with a rate of 10℃·min-1 and maintained for 5 min. The inlet temperature was 200℃. The detector was a flame ionization detector (FID) and the temperature was 250℃. The flow rate was 1. 8 ml ·min-1 split ratio was 1∶30 and the carrier gas was nitrogen. Results:The linear range was 0. 6-1. 8 mg·ml-1 . The average recovery was 96. 0% (RSD=2. 6%,n=9). The content of 3 batches of the samples was 99. 3%, 98. 7% and 98. 4%, respectively. Conclu-sion:The established quantitative analysis method is applicable in the quality control of metacresol.

Objective:To establish a GC method for the determination of residual organic solvents in lidocaine patches. Methods:GC was carried out on a DB-WAX capillary column (30 m × 0. 25 mm, 0. 5 μm). The detector was FID and the carrier gas was He. The initial temperature was 50℃, maintained for 8 min, and then raised to 250℃ with a rate of 50℃ per min. The inlet temperature and the detector temperature were 280℃. The separation was 50 ∶1. Results:The linear range of acetone, ethyl acetate and methanol was 15. 0-600. 0 μg·ml-1. The average recovery was 97. 4% (RSD =3. 2%, n=9), 95. 6% (RSD=1. 9%, n=9) and 112. 0%(RSD =4. 5%, n=9), respectively. Conclusion:The method is simple and accurate,which can be used for the determination of re-sidual organic solvents in lidocaine patches.