title: Quantitative determination of the okadaic acid toxins group by a colorimetric phosphatase inhibition assay: interlaboratory study.
abstract: An interlaboratory collaborative study to validate a colorimetric phosphatase inhibition assay for quantitative determination of the okadaic acid (OA) toxins group in molluscs, OkaTest, was conducted. Eight test materials, including mussels, scallops, clams, and cockles, were analyzed as blind duplicates. Blank samples and materials containing different OA toxin levels ranging from 98 to 275 microg/kg OA equivalents were included. The study was carried out by a total of 16 laboratories from 11 different countries. Values obtained for repeatability relative standard deviations (RSDr) ranged from 5.4 to 11.2% (mean 7.5%). Reproducibility RSD (RSD(R)) values were between 7.6 and 13.2% (mean 9.9%). The Horwitz ratio (HorRat) values ranged between 0.4 and 0.6. A recovery assay was also carried out using a sample spiked with OA. A mean recovery of 98.0% and an RSD of 14.5% were obtained. The results obtained in this validation study indicate that the colorimetric phosphatase inhibition assay, OkaTest, is suitable for quantitative determination of the OA toxins group. OkaTest could be used as a test that is complementary to the reference method for monitoring the OA toxins group.
authors.affiliation: ZEU-INMUNOTEC, C/Bari 25 Dpdo. 50197, Zaragoza, Spain.
authors.forename: Henry
authors.initials: H
authors.lastname: Smienk
authors.forename: Elena
authors.initials: E
authors.lastname: Domínguez
authors.forename: María L
authors.initials: ML
authors.lastname: Rodríguez-Velasco
authors.forename: David
authors.initials: D
authors.lastname: Clarke
authors.forename: Katrin
authors.initials: K
authors.lastname: Kapp
authors.forename: Panagiota
authors.initials: P
authors.lastname: Katikou
authors.forename: Ana G
authors.initials: AG
authors.lastname: Cabado
authors.forename: Alberto
authors.initials: A
authors.lastname: Otero
authors.forename: Juan M
authors.initials: JM
authors.lastname: Vieites
authors.forename: Pedro
authors.initials: P
authors.lastname: Razquin
authors.forename: Luis
authors.initials: L
authors.lastname: Mata
mesh_terms: D003124:Colorimetry / Q000379:methods*; D004791:Enzyme Inhibitors / Q000032:analysis*; D019319:Okadaic Acid / Q000032:analysis*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D015203:Reproducibility of Results
chemical_list: D004791:Enzyme Inhibitors; D019319:Okadaic Acid; D010749:Phosphoprotein Phosphatases