Label-free biochemical detection coupled on-line to liquid chromatography

The on-line coupling of a label-free optical biosensor to a HPLC system is described by combining the separation power of HPLC with the specificity of the biosensor system. A highly cross-reactive antibody against the pestici de isoproturon was used as model for affinity proteins, The binding strengt h of the antibody to the utilized pesticides was characterized with the bio sensor, first. In the on-line coupling setup, the eluate of the HPLC was mi xed continuously with the antibodies. The presence of antigens was detected by a reduction of the antibody binding to the transducer. This reduced bin ding was quantified by a differentiation of the sensor signal by applying a Savitzky-Golay algorithm. Limits of detection were found to be in the femt omole range without preconcentration, which is comparable to a study using fluorescence-based biochemical detection.