title: Development and single-laboratory validation of a pseudofunctional biosensor immunoassay for the detection of the okadaic acid group of toxins.
abstract: A rapid analytical optical biosensor-based immunoassay was developed and validated for the detection of okadaic acid (OA) and its structurally related toxins from shellfish matrix. The assay utilizes a monoclonal antibody which binds to the OA group of toxins in order of their toxicities, resulting in a pseudofunctional assay. Single-laboratory validation of the assay for quantitative detection of OA determined that it has an action limit of 120 microg/kg, a limit of detection of 31 microg/kg, and a working range of 31-174 microg/kg. The midpoint on the standard matrix calibration curve is 80 microg/kg, half the current regulatory limit. Inter- and intra-assay studies of negative mussel samples spiked with various OA concentrations produced average coefficient of variation (CV) and standard deviation (SD) values of 7.9 and 10.1, respectively. The assay was also validated to confirm the ability to accurately codetect and quantify dinophysistoxin-1 (DTX-1), DTX-2, and DTX-3 from shellfish matrix. Alkaline hydrolysis was not required for the detection of DTX-3 from matrix. Excellent correlations with the data generated by the biosensor method and liquid chromatography/tandem mass spectrometry (LC/MS/MS) were obtained using a certified reference material (R(2) = 0.99), laboratory reference material, and naturally contaminated mussel samples (R(2) = 0.97). This new procedure could be used as a rapid screening procedure replacing animal-based tests for DSP toxins.
authors.affiliation: Institute of Agri-Food and Land Use, Queen's University of Belfast, Stranmillis Road, Belfast, Northern Ireland BT9 5AG. l.stewart@qub.ac.uk
authors.forename: Linda D
authors.initials: LD
authors.lastname: Stewart
authors.forename: Philipp
authors.initials: P
authors.lastname: Hess
authors.forename: Lisa
authors.initials: L
authors.lastname: Connolly
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Elliott
mesh_terms: D000818:Animals; D015374:Biosensing Techniques; D002853:Chromatography, Liquid; D007118:Immunoassay; D008387:Marine Toxins / Q000737:chemistry*; D019319:Okadaic Acid / Q000032:analysis* / Q000031:analogs & derivatives; D011714:Pyrans / Q000032:analysis; D012758:Shellfish; D053719:Tandem Mass Spectrometry
chemical_list: D008387:Marine Toxins; D011714:Pyrans; C092883:dinophysistoxin 3; D019319:Okadaic Acid; C051904:dinophysistoxin 1; C076221:dinophysistoxin 2