Simultaneous Determination of Four Residual Solvents in Fluorene Derivatives by Headspace-Gas Chromatography

Headspace-gas chromatography was applied to the simultaneous determination of 4 residual solvents (i.e., methanol, ethanol, 1,4-dioxane and toluene) in fluorene derivatives. The sample (0.500 0 g) was placed into the 20 mL headspace flask and dissolved in 1 mL of N,N-dimethylformamide. The flask was then closed tightly. Equilibrium temperature and time taken for headspace sampling were 100 ℃ and 30 min. The capillary chromatographic column SE 54, using a mixture of diphenyl siloxane and dimethyl siloxane mixed by volume ratio of 5 to 95 as stationary phase was used as separation column on which the 4 solvents were separated clearly. Hydrogen flame ionization detector was adopted for detection and external standard method was used for quantification. Linearity ranges of the standard curves for methanol and ethanol were same between 8.0 to 800 mg·L^-1, which for 1,4-dioxane and toluene were same between 10.0 to 1 000 mg·L^-1, with limits of detection (3S/N) of 10.30, 10.51, 24.87, 25.79 μg·L^-1 for the 4 solvents respectively. Test for recovery was made by addition of standards at 3 concentration levels, giving average recoveries of 99.4% (for CH₃OH), 100% (for C₂H₅OH), 101% (for 1,4-dioxane) and 100% (for toluene).