Feasibility of gamma irradiation as a stabilisation technique in the preparation of tissue reference materials for a range of shellfish toxins

Abstract

The effect of γ-irradiation on concentrations of hydrophilic and lipophilic phycotoxins has been investigated by use of HPLC-UV and LC-MS. Pure toxins in organic solvents and toxins in mussel (Mytilus edulis) tissues were irradiated at three different doses. In solution all toxin concentrations were reduced to some extent. Most severe decreases were observed for domoic acid and yessotoxin, for which the smallest dose of irradiation led to almost complete destruction. For pectenotoxin-2 the decrease in concentration was less severe but still continuous with increasing dose. Azaspiracid-1 and okadaic acid were the least affected in solution. In shellfish tissue the decrease in toxin concentrations was much reduced compared with the effect in solution. After irradiation at the highest dose reductions in concentrations were between ca. 5 and 20% for the lipophilic toxins and there was no statistical difference between control and irradiated samples for azaspiracids in tissue. Irradiation of shellfish tissues contaminated with domoic acid led to a more continuous decrease in the amount of the toxin with increasing dose. The effect of irradiation on the viability of microbial activity in shellfish tissues was assessed by using total viable counting techniques. Microbial activity depended on the type of shellfish and on the pretreatment of the shellfish tissues (with or without heat treatment). As far as we are aware this is the first investigation of the effectiveness of irradiation as a technique for stabilising tissue reference materials for determination of phycotoxins. Our results suggest that this technique is not effective for materials containing domoic acid. It does, however, merit further investigation as a stabilisation procedure for preparation of shellfish tissue materials for some lipophilic toxins, in particular azaspiracids.

A mussel tissue certified reference material for multiple phycotoxins. Part 4: certification

“…With the increased use of LC-MS for multi-toxin monitoring, the need for a CRM certified for multiple groups of toxins has also increased. An international collaboration to produce a freeze-dried mussel tissue (Mytilus edulis) CRM (CRM-FDMT1) [11] was initiated following a series of feasibility studies [7,[11][12][13][14][15]. This Electronic supplementary material The online version of this article (doi:10.1007/s00216-016-0004-0) contains supplementary material, which is available to authorized users.…”

A mussel (Mytilus edulis) tissue certified reference material for the marine biotoxins azaspiracids

“…The decision to proceed with the production of a wet tissue homogenate is strengthened when it is considered that this matrix is very similar to the type of wet shellfish samples generally received as part of routine regulatory monitoring programs. Feasibility studies showed that γ-irradiation was suitable as a stabilization procedure for use in the preparation of AZA RMs, and it was demonstrated that the treatment was highly effective in eliminating microbial activity in shellfish tissue RMs after they have been bottled [32]. Irradiation was therefore selected as a post-bottling stabilization process for CRM-AZA-Mus.…”

“…The bottles were transported on dry ice to the Agriculture and Agri-Food Canada facility in Ste-Hyacinthe (Quebec, Canada) for γ-irradiation. The irradiation dose received by all bottles was in the range of 14.3 to 19.4 kGy (γ-irradiation, source cobalt 60) [32]. The bottles were returned frozen to the NRCC in Halifax for sealing (12ASD Heat Sealer, Sentinal Packaging Inc., Hyannis, MA, USA) inside trilaminate lightproof foil pouches (Retort Pouches, ISE USA Inc).…”

A mussel tissue certified reference material for multiple phycotoxins. Part 1: design and preparation

“…Extracts were combined in 25 mL volumetric flasks and made up to the mark with extraction solvent [30]. OA group esters were determined using the base hydrolysis method [41].…”

“…However, this method is inappropriate for the AZAs [29]. A feasibility study on gamma-irradiation showed that it was suitable for various toxin groups [30] . However, long-term stability information is not available for this treatment for many of the toxin of interest in this project.…”