Procedures for extracting organic micro-pollutants from water samples to monitor toxicological stress

Methods that are elemental in toxicity monitoring of the aqueous compartment have been validated. One method has recently been implemented in a joint pilot monitoring of an RIVM/RIZA project to map the toxic potency of Dutch surface waters in terms of the Potentially Affected Fraction of species (PAF measured). Three procedures, partly laid down in Standard Operation Procedures, to obtain a 'water concentrate' of a surface-water sample were compared. All three rely on the use of macro-reticular resins of the XAD type to extract organic micro-pollutants from water, but are different as to how the toxicants are returned to the water phase. The performance of the methods was evaluated by comparing the chemical recovery of well-defined test mixtures. Increasing loss of test compounds was measured using two methods applied to chemicals in the (semi-)volatile range of 0.1 to 100 Pa.m3/mol. A new approach, based on the application of super-critical fluid extraction, the upper limit above which total loss of (volatile) substances was apparent, could be increased up to 2000 Pa.m3/mol