Determination of 54 Volatile Hydrocarbons by Thermal Desorption-Gas Chromatography in Workplace Air

A method was developed for the determination of 54 volatile hydrocarbons in workplace air by thermal desorption/gas chromatography-hydrogen flame ionization detector. The workplace air was adsorbed by Tenax-TA thermal desorption tubes, then desorbed by thermal desorption and detected by gas chromatography. The experimental results indicated that the coefficients efficiency of 1, 1-dichloroethylene, dichloromethane, trans-1, 2-dichloroethylene, cis-1, 2-dichloroethylene, 2, 2-dichloropropane, bromochloromethane, 1, 1, 1-trichloroethane, 1,2-diehloroethane, 1,1-dichloropropene were 0.9941 - 0.9986. The detection limits of bromochloromethane, dibromomethane, trichloromethane, bromodichloromethane, 2,2-diehloropropane, dibromochloromethane, bromoform were 5.4 - 10.3 ng, the minimum detectable concentration was 0.01 - 0.1 mg/m(3) (the air volume = 0.5 L). The coefficients efficiency of other 38 volatile hydrocarbons was above 0.999, the minimum detectable concentration were 0.001 - 0.01 mg/m3. The detection limits of alkenes were 0.4 - 2.7 ng, alkanes 1.4 - 3.7 ng, aromatic hydrocarbons 0.2 - 1.0 ng and naphthalene 2.2 ng. The desorption efficiencies of 54 volatile hydrocarbons were 92.1% - 113.1% and the relative standard deviations (RSDs) were 0.6% - 17.4%. Except for the RSD values of cis-1,2-dichloroethylene, 1, 1-dichloroethane, 1, 1, 1-trichloroethane, 1, 1-dichloroethylene, 2, 2-dichloropropane, trichloromethane, trans-1, 2-dichloroethylene, dichloromethane, bromochloromethane were 5.1% - 17.4%, those of other volatile hydrocarbons were below 5%; The experimental results indicated that the breakthrough capacities of 9 volatile hydrocarbons were 400 - 4000 ng, those of the other volatile hydrocarbons were above 10 mu g. Except for the loss rates of 2,2-dichloropropane, bromodichloromethane were 10% - 15% in stable experiment, those of other volatile hydrocarbons in Tenax desorption tubes were below 5%, which indicated that 54 volatile hydrocarbons stored in Tenax tubes were stable. The method is a quick and accurate for the detection of volatile hydrocarbons in workplace air.