SIMULTANEOUS DETERMINATION OF VOLATILE ORGANIC POLLUTANTS IN WATER BY HEADSPACE GAS-CHROMATOGRAPHIC ANALYSIS WITH DUAL DETECTION

Headspace gas chromatographic analysis using a semi-wide bore capillary column and a dual detection system with a flame ionization detector (FID) and an electron capture detector (ECD) was carried out for the simple and rapid simultaneous determination of 13 kinds of volatile organic pollutants: benzene (1), toluene (2), ethyl benzene (3), o-, m- and p-xylenes (4-6), monochlorobenzene (7), o-, m- and p-dichlorobenzenes (8-10), 1,1,1-trichloroethane (11), trichloroethylene (12) and tetrachloroethylene (13) in drinking water at low ppb (10(-9) g/ml) level. The effects of the headspace and syringe temperatures as well as the equilibration time and injection volume of headspace gas on the sensitivity and reproducibility of analysis were examined to find the optimal conditions. The capillary column permitted satisfactory separation of the target compounds except m- and p-xylenes (5 and 6) without interference by trihalomethanes in drinking water. FID was sensitive to all aromatic hydrocarbons (1-6) and monochlorobenzene (7) at 0.3-0.5 ppb, while ECD was poorly sensitive to them. By contrast, ECD was highly sensitive to chlorinated hydrocarbons (11-13) and aromatic chlorinated hydrocarbons except monochlorobenzene (8-10) with detection limits of 0.005-0.02 and 0.2-0.6 ppb, respectively, while FID was poorly sensitive to them. The coefficients of variation (n = 4) in the simultaneous analysis using FID and ECD for sample water containing 0.1-20 ppb of the target compounds were 3.4-7.4% with good precision and reproducibility.