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.

Occurrence and profiles of lipophilic toxins in shellfish harvested from Argentina

“…Uncited references Q2 Anon, 2005;Dickey et al, 1993; European Food Safety Authority, 2008;Fern andez et al, 2003;Hess, 2010;Hummert et al, 1995;Lacaze et al, 2007;Lee et al, 1987Lee et al, , 1989McCarron et al, 2011;Satake et al, 1997Satake et al, , 1999Smienk et al, 2013;Suzuki et al, 2011;Yasumoto and Takizawa, 1997;Yasumoto et al, 1995. …”

Dinophysis Toxins: Causative Organisms, Distribution and Fate in Shellfish

“…Several PP inhibition assays (PPIA), using different phosphatase sources and colorimetric or fluorimetric substrates, have been developed [316,317,318,319,320,321]. Recently, a colorimetric PPIA, OkaTest, has been interlaboratory-validated for quantification of the OA toxin group in molluscs [322], and it could be also applied for Dinophysis cell samples. This colorimetric PPIA, OkaTest, could be used as a complementary (screening) assay to the reference method for determination of OAs in molluscs according to Commision Regulations (EC) No.…”

Effect of the industrial steaming on the toxicity, estimated by LC–MS/MS, of mussels exposed for a long time to diarrhetic shellfish poisoning (DSP) toxins

“…In order to limit the possible impacts, different monitoring systems have been established, especially in developed countries, which use several techniques and methods to determine the toxicity or toxin concentration of the bivalves. Traditionally, mouse bioassays have been used to monitor this group of toxins (EU-RL-MB, 2013;Fernández & Cembella, 1995;Fernández et al, 2002Fernández et al, , 2003, but in recent years other methodologies, such as liquid chromatography coupled to mass spectrometry through electrospray interfaces (Gerssen, Mulder, McElhinney, & de Boer, 2009;Quilliam, 2003;Regueiro, Rossignoli, Álvarez, & Blanco, 2011), or phosphatase inhibition assays (Eberhart et al, 2013;Garibo et al, 2012;Smienk et al, 2013), have been widely implemented.…”