Extension of the Validation of AOAC Official MethodSM 2005.06 for dc-GTX2,3: Interlaboratory Study

Abstract

AOAC Official Method(SM) 2005.06 for the determination of saxitoxin (STX)-group toxins in shellfish by LC with fluorescence detection with precolumn oxidation was previously validated and adopted First Action following a collaborative study. However, the method was not validated for all key STX-group toxins, and procedures to quantify some of them were not provided. With more STX-group toxin standards commercially available and modifications to procedures, it was possible to overcome some of these difficulties. The European Union Reference Laboratory for Marine Biotoxins conducted an interlaboratory exercise to extend AOAC Official Method 2005.06 validation for dc-GTX2,3 and to compile precision data for several STX-group toxins. This paper reports the study design and the results obtained. The performance characteristics for dc-GTX2,3 (intralaboratory and interlaboratory precision, recovery, and theoretical quantification limit) were evaluated. The mean recoveries obtained for dc-GTX2,3 were, in general, low (53.1-58.6%). The RSD for reproducibility (RSD(r)%) for dc-GTX2,3 in all samples ranged from 28.2 to 45.7%, and HorRat values ranged from 1.5 to 2.8. The article also describes a hydrolysis protocol to convert GTX6 to NEO, which has been proven to be useful for the quantification of GTX6 while the GTX6 standard is not available. The performance of the participant laboratories in the application of this method was compared with that obtained from the original collaborative study of the method. Intralaboratory and interlaboratory precision data for several STX-group toxins, including dc-NEO and GTX6, are reported here. This study can be useful for those laboratories determining STX-group toxins to fully implement AOAC Official Method 2005.06 for official paralytic shellfish poisoning control. However the overall quantitative performance obtained with the method was poor for certain toxins.

An improved sensitive assay for the detection of PSP toxins with neuroblastoma cell-based impedance biosensor

“…To date, the official methods for PSP toxins detection are the mouse bioassay (MBA) and the pre-column oxidation liquid chromatography with fluorescence detection (ox-LC-FLD) (Turner et al, 2011;Ben-Gigirey et al, 2012;Meneely et al, 2013;Nicolas et al, 2014). The first analytical method permitted by the government in PSP toxins detection is ox-LC-FLD (Humpage et al, 2010).…”

Review and analysis of occurrence, exposure and toxicity of cyanobacteria toxins in food

“…Several authors reported the use of the so-called Lawrence method (AOAC Official method 2005.06) (Ben-Gigirey et al, 2012;Botelho et al, 2010;Devlin et al, 2011;Rawn et al, 2009;Turner EFSA Supporting publication 2016:EN-998 The present document has been produced and adopted by the bodies identified above as authors. This task has been carried out exclusively by the authors in the context of a contract between the European Food Safety Authority and the authors, awarded following a tender procedure.…”

“…Ben-Gigirey et al (2012) introduced a hydrolysis step to convert GTX6 in NEO for which a standard is available. The fraction 2 collected after COOH SPE cleanup was hydrolysed with HCl, in a water bath, and the reaction was stopped with NaOH.…”

“…As part of the AOAC Official Method 2005.06, the SPE-cleaned extracts go through periodate and peroxide oxidation procedures prior to the injection in the LC-FLD system (Ben-Gigirey et al, 2012;Botelho et al, 2010;Turner et al, 2014).…”

“…SPE-COOH ion exchange cleanup is used only for extracts that are found to contain N-1-hydroxylated PSP toxins after C18 cleanup. Three fractions are collected from the cartridge containing respectively the (i) Ctoxins, (ii) the GTXs with B1 and B2 and (iii) NEO, STX, and dcSTX (Ben-Gigirey et al, 2012;Botelho et al, 2010;Turner et al, 2014).…”