Interlaboratory comparison study for the determination of halogenated hydrocarbons in water

Sixty laboratories of five different countries participated in a large-scal e interlaboratory comparison test for the determination of halogenated hydr ocarbons in water. Participants used their in-house method with 44 laborato ries applying head space GC ECD analysis and 5 using liquid/liquid extracti on. A set of two artificially produced samples was prepared; the halogenate d hydrocarbons investigated were trichloroethylene, tetrachloroethylene, 1, 1,1-trichloroethane, trichloromethane, terrachloromethane, 1,1-dichloroethy lene, dichloromethane, dibromochloromethane, bromodichloromethane, 1,2-dich loroethane and tribromomethane. The procedure of sample preparation, storag e and distribution was monitored by an extensive quality assurance system i ncluding homogeneity tests, stability tests, and trend analysis of the subm itted data. The analytical results submitted by the participants exhibited RSD values of up to 35% and outlier rates of up to 19%. The percentage of f alse positive and false negative results was at the highest 12% for selecte d substances. Recovery rates varying from 86% to 106% proved the correctnes s of the analytical results submitted by the participants and showed that t he procedure developed in this study for sample preparation and distributio n is well suited for the performance of large-scale interlaboratory compari son tests of halogenated hydrocarbons in water.