WATER-QUALITY CONTROL IN THE PRODUCTION OF DRINKING-WATER FROM RIVER WATER - THE APPLICATION OF IMMUNOLOGICAL TECHNIQUES FOR THE DETECTION OF CHLOROPHENOXY ACID HERBICIDES (2,4-D)

In the production of drinking water from river water, the quality of t he raw water is extremely important. For this reason the Water Transpo rt Company Rhine-Kennemerland (WRK) operates, among others, an early w arning system. This system was found to be inappropriate for the detec tion of certain chlorophenoxy herbicides (e.g., 2,4-D, MCPP, MCPA and 2,4-DP) that are occasionally found in the Rhine in increased levels ( above the drinking water norm of 0.1 mu g l(-1)). Commercially availab le immunoassay kits were evaluated for use in pre-screening. With some modifications to adapt the working range and to enhance the sensitivi ty of the kits, they were found to be applicable in the early warning. Comparison with a gas chromatography-mass spectrometry reference anal ysis revealed no false negative results and a rate of false positive r esults of about 10%. However, it should be taken into account that mat rix effects may affect the results. A daily sampling frequency combine d with an analysis frequency based on the actual flow in the river all owed for a periodic batchwise analysis. This permitted a timely availa bility of the results as well as a cost-effective use of the (modified ) kits.