DEVELOPMENT OF A FLOW FLUOROIMMUNOSENSOR FOR DETERMINATION OF THEOPHYLLINE

A new fluorescence immunosensor for theophylline with on-line incubation and in situ fluorescence detection was developed to overcome interference problems and speed up sample throughput. Protein A on controlled-pore glass acts as a solid-phase immunoreactor sited in the flow cell of the spectrofluorimeter. The immunosensor has a limit of detection of 0.3 ng ml(-1), a throughput of 10-12 samples per hour and high reproducibility (4.4% at 2.5 ng ml(-1) and 3.3% at 3.75 ng ml(-1)) and selectivity, Possible interferents such as 7-(2,3-dihydroxypropyl) theophylline, caffeine and aminophylline do not interfere up to concentrations 50-fold higher than that of the theophylline present, This immunosensor was successfully applied to the determination of theophylline in serum samples.