Determination of Residual Organic Solvents in Melatonin Analogue by GC

OBJECTIVE To establish a capillary GC method for the determination of residual organic solvents including ethanol, ethyl acetate, methylene chloride, tetrahydrofuran and toluene in melatonin analogue. METHODS The residual organic solvents were separated on DB-Wax capillary column(30 m×0.45 mm, 0.85 μm). FID was used as detector with a temperature of 250 ℃, and the inlet temperature was 200 ℃. The carrier gas was nitrogen, and the flow rate was 3.5 mL·min^-1. The programmed column temperature was set as follows: maintained at 45 ℃ for 9 min and raised to 200 ℃ at the rate of 30 ℃·min^-1 followed by holding for 9 min. The sample dissolved in dimethylsulfoxide and acetonitrile was used as the internal standard. The assay of residual solvents was calculated by internal standard method. RESULTS Five residual organic solvents were completely separated. The linear ranges of ethanol, ethyl acetate, methylene chloride, tetrahydrofuran and toluene were 107.44-1 074.4 μg·mL^-1(r=0.999 9), 108.24-1 082.4 μg·mL^-1(r=0.999 7), 18.550-185.50 μg·mL^-1(r=0.999 8), 14.208-142.08 μg·mL^-1(r=0.999 4), 19.074-190.74 μg·mL^-1(r=0.999 9), the average recovery of the preparation were between 98%-102%. CONCLUSION The method is simple, sensitive, accurate, and can be used for the determination of the residual organic solvents in melatonin analogue.