As azaspiracids (AZAs) are being reported from the coastal waters of an increasing number of countries on a global scale, the need for rapid, simple and cost-effective methods to detect these marine toxins and protect seafood consumers' health is becoming evident. A magnetic bead (MB)-based direct immunoassay for the detection of AZAs, using protein G-coated MBs as supports for antibody immobilisation and peroxidase-labelled AZA as a tracer is detailed. A colorimetric approach was first developed to optimise the experimental parameters and establish the cross-reactivity factors for AZA-1-10. The subsequent combination of the immunorecognition MBs with 8-electrode arrays enabled the multiplexed electrochemical detection of AZAs. Naturally-contaminated mussel samples were analysed and the results obtained showed an excellent correlation with LC-MS/MS analysis. The MB-based immunoassay facilitated the quantification of a wide range of AZA concentrations (120-2875μg AZA-1 equiv./kg), with a limit of detection (63μg AZA-1 equiv./kg) below the European regulatory threshold, using a protocol that requires very few steps and a short analysis time (~ 15min). The simplicity, cost-effectiveness, rapidity, robustness, selectivity and precision of the assay provide a valuable tool for the detection of all regulated AZAs and other toxic AZA analogues, suitable for end users in the field of food safety.
Keywords: Azaspiracid; Electrochemical; Horseradish peroxidase; Immunoassay; Magnetic bead; Mussel.
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