New developments in immunochemical water analysis down to 30 mul sample volume

The determination of trace levels of pesticides like atrazine in water samples of small, restricted volumes is one of the future demands of environmental analysis. In a brief review existing chromatographic and immunochemical methods for atrazine are critically discussed. Then a simple rapid enzyme-linked immunosorbent assay (ELISA) using the tip of an inoculation needle as a solid surface is presented. The sample volume could be reduced to 30 mul. The assay had a centre of the test IC(50) of 0.12 mug l(-1) and permitted the characterisation of atrazine at levels of 0.022-2.90 mug l(-1). A first outlook for automatisation is given. The new method was compared with an ELISA using 96 well microtiter plates as a solid phase. Surface water samples with low atrazine contents were analysed to check the new method.