Multicommuted fluorescence based optosensor for the screening of bitertanol residues in banana samples

A multicommuted flow through optosensor is developed in order to determine bitertanol in banana samples, by measuring the pesticide native fluorescence at 261/326 nm. The solid support used in the flow-through cell, C18, allows both high selectivity and sensitivity necessary for the screening of the pesticide at residue levels. These characteristics of optosensing are implemented with low sample consumption and automation intrinsic properties of multicommutation, providing a useful tool for pesticide residue routine determination in foods. An acetonitrile extraction/partitioning and dispersive solid-phase extraction clean-up procedure proved to be useful; an additional cleaning step with C18 solid phase extraction (SPE) cartridges was carried out, eliminating all matrix limitations. Recovery experiments performed on banana samples at different concentrations provided recoveries between 81% and 115%. A detection limit of 0.014 mg kg−1 was obtained. This makes the method suitable for screening bitertanol in banana samples, fulfilling the maximum residue levels of 3 mg kg−1 established by the European Union.