COMPARISON BETWEEN AN ENZYME-LINKED-IMMUN OSORBENT-ASSAY AND A GAS-CHROMATOGRAPHIC PROCEDURE FOR THE DETERMINATION OF DILUTED FRACTIONS OF ATRAZINE IN RUNOFF WATER

The response of a non-specific enzyme-liked immunosorbent assay (EIisa ) for triazines was compared to a gas chromatography technique specifi c for atrazine by using diluted fractions (1:800, 1:2000 and 1:2000) o f runoff water containing high atrazine concentrations. Elisa was used because it could be applied in routine analysis of waters for screeni ng or monitoring purposes and no attempt was made to improve ol valida te the method. Four atrazine metabolites were also analyzed by chromat ography in order to examine the risk of their potential interference o n the determination of atrazine by the Elisa. Comparisons showed that the highest dilution (1:2000) exhibited the poorest correlation betwee n the results obtained from the Elisa and by GC (r = 0.63). When using the mean of the sample concentrations (direct measurements x dilution factor) determined by the Elisa from the three dilutions, a moderate relationship was found with GC (r = 0.82). Even if the EIisa overestim ated (32 %) the atrazine concentration as determined by GC, this assay was found to be useful for the sceening of triazines in diluted fract ions of highly concentrated water.