Determination of hydrocarbons in water interlaboratory method validation before routine monitoring

The clarification of hydrocarbon input into the Baltic sea via rivers is on e of the priority issues of the 4th Pollution Load Compilation (PLC-4) with in the framework of international Baltic Sea marine monitoring. An interlab oratory comparison was conducted to check the applicability of a new method for the determination of hydrocarbons by solvent extraction and gas chroma tography. Surrogate oil solutions with known hydrocarbon content were distr ibuted among the participants for preparation of water samples of different hydrocarbon concentration. In using these concentrations as assigned value s and by setting target values for precision,the proficiency of participati ng laboratories could be tested as a qualifying step before involvement in PLC-4 routine monitoring. The results of the exercise indicate that hydroca rbons in water samples can be monitored as a mandatory test item within the framework of PLC-4.