Sol-gel glass doped with isoproturon antibody as selective support for the development of a flow-through fluoroimmunosensor

In this work, isoproturon was determined in a competitive fluoroimmunoassay with a reactive phase constituted by an antibody encapsulated in a sol-gel matrix, this kind supports increase the selectivity of immunoassay. The parameters affecting both the entrapment of the antibody and the immunoreaction were optimized. The immunosensor developed has a detection limit of 2 mug l(-1) and a dynamic range of 0.002-0.2 and 0.004-1 mg l(-1), depending on the amount of antibody immobilized. The relative standard deviation (R.S.D.) obtained for 10 measurements was 6% at 0.05 mg l(-1) level and 4% at 0.15 mg l(-1) level. The cross-reactivity of the phenylurea-related compounds tested was negligible. The method developed was applied to the determination of isoproturon in sea-water and potato-enriched extracts obtaining, in all cases, recoveries higher than 94%. The matrix effects observed when analyzing these types of samples using other antibody immobilized supports were minimized when using the antibody entrapped in sol-gel glass. (C) 2001 Elsevier Science B.V. All rights reserved.