Determination of 4-n-nonylphenol in water by enzyme immunoassay

A range of monoclonal antibody-based competitive immunoassays in the format of microtitre plate ELISA and dipstick tests for quantitative and semi-quantitative detection of 4- n -nonylphenol in water was developed. A simple visual dipstick test was based on changing of spot colour from green to brown in the presence of 4- n -nonylphenol at concentrations within the range 10-100 ng mL(-1). Two different detection systems were used for quantitative immunoassay. Application of enhanced chemiluminescence (ECL) resulted in an increase of the sensitivity of ELISA when compared to conventional colorimetric detection. Thus a detection limit of 0.06 ng mL(-1 )of 4- n -nonylphenol was achieved with IC(50) 2.0 ng mL(-1). The tests developed were applied to natural and spiked water samples.