Immune affinity extraction of pesticides from surface water

The polar nature of present-day pesticides and the low levels in surface wa ter make them difficult to analyze using available analytical instrumentati on. Preconcentration is generally required which makes such methods complex and costly. Immune affinity chromatography (IAC) seemed to be promising as a preconcent ration technique due to the intrinsic selectivity and sensitivity of the un derlying immunochemistry. The present study was, therefore, undertaken in o rder to find out whether a selective enrichment of a number of target pesti cides could be achieved using IAC in a cast-effective way. Atrazine, 2,4-D, aldicarb and glyfosate were chosen as target pesticides an d off-line columns were constructed using various antibodies and solid phas es. These columns were evaluated regarding selectivity, recovery, capacity and certain other performance criteria, as well as the reusability. Pestici de analyses were done using immune assay as well as LC and/or GC. The results clearly demonstrate the potential application of IAC in pestici de analysis. Repeated use (>20 times) had no significant influence on colum n stability, provided certain precautions were taken. However, the performa nce 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 w here they may be useful for extracting, purifying and concentrating selecte d groups of polar pesticides from surface water samples. (C) 1999 Elsevier Science B.V. All rights reserved.