Direct Surface Plasmon Resonance immunosensing of Pyraclostrobin residues in untreated fruit juices
E.Mauriz, C. García-Fernández, J.V. Mercader, A. Abad-Fuentes, A. Medina-Escuela and L. M. Lechuga
Ana. Bional. Chemistry, 404, 2012, 2877-2886 - DOI: DOI 10.1007/s00216-012-6321-z
Abstract: A Surface Plasmon Resonance (SPR) immunoassay for the on-line detection of the strobilurin fungicide pyraclostrobin in untreated fruit juices is presented. The analysis of pyraclostrobin residues is accomplished in apple, grape and cranberry samples by monitoring the recognition events occurring separately in a two-channelled home-made SPR biosensor. The covalent coupling of the analyte derivative enables the reversibility of the method allowing more than 80 measurements on the same sensor surface. Optimization of the immunoassay conditions provides limits of detection as low as 0.16 g L-1. The selectivity and reproducibility of the analysis is ensured by studying both non-specific interactions with non-related compounds and inter-assay coefficients of variation. Excellent recovery values ranging from 98 to 103% are attained by a simple 1:5 dilution of fruit juice samples in assay buffer before the analysis. The lack of previous cleansing and homogenization procedures reduces the analysis time of a single food sample to only 25 minutes including the regeneration cycle.