An immunosensor for the automatic determination of the antifouling agent Irgarol 1051 in natural waters

The development of an immunosensor for analysis of the antifouling agent Irgarol 1051 (2-methylthio-4-tert-butylamin-6-cyclopropylamin-s-triazine) is described. The immunosensor is based on a heterogeneous competitive enzyme immunoassay and uses binder azlactone support with immobilized protein A/G. The flow-through immunosensor is completely automated and is able to carry out a whole analysis cycle in about 23 min. Competitive calibration curves have an I-50 value of 0.053 mu g/L (0.21 nM), with a limit of detection of 0.010 mu g/L and a quantification dynamic range from 0.019 to 0.158 mu g/L. The protein A/G support can be used for more than 600 assay cycles without loss Of sensor performance. The sensor is prone to some interferences from tert-butyl-containing s-triazine compounds, such as terbutryn and terbumeton, bur little inteference is shown for other s-triazine compounds, e.g., atrazine or simazine. The developed sensor is applied to the determination of trace levels of Irgarol 1051 in water samples such as Mediterranean marina and beach seawater, estuarine river water, and lake water, without any sample pretreatment other than adjusting the pH and ionic strength of samples to those of standards. Good correlation is achieved between the immunosensor results and ELISA or HPLC analyses.