Immuno affinity extraction of pesticides from surface water

Abstract

The polar nature of present-day pesticides and the low levels in surface water make them difficult to analyze using available analytical instrumentation. Preconcentration is generally required which makes such methods complex and costly. Immuno affinity chromatography (IAC) seemed to be promising as a preconcentration technique due to the intrinsic selectivity and sensitivity of the underlying immunochemistry. The present study was, therefore, undertaken in order to find out whether a selective enrichment of a number of target pesticides could be achieved using IAC in a cost-effective way. Atrazine, 2,4-D, aldicarb and glyfosate were chosen as target pesticides and off-line columns were constructed using various antibodies and solid phases. These columns were evaluated regarding selectivity, recovery, capacity and certain other performance criteria, as well as the reusability. Pesticide analyses were done using immuno assay as well as LC and/or GC. The results clearly demonstrate the potential application of IAC in pesticide analysis. Repeated use (>20 times) had no significant influence on column stability, provided certain precautions were taken. However, the performance of the columns varied depending on the type and the amount of antibody used. Off-line IAC columns appear to be particularly suited for qualitative or semiquantitative measurements, e.g. in the identification of ‘hot spots’. Furthermore, the results indicate a potential for on-line applications where they may be useful for extracting, purifying and concentrating selected groups of polar pesticides from surface water samples.