Determination of paralytic shellfish toxins in shellfish by receptor binding assay: collaborative study

Area of Science:

• Marine Biology
• Analytical Chemistry
• Food Safety

Background:

• Paralytic shellfish toxins (PST) pose a significant public health risk, necessitating reliable detection methods.
• Current validated methods for PST detection, like the mouse bioassay, have limitations.
• A microplate receptor binding assay (RBA) was developed to quantify composite PST toxicity.

Purpose of the Study:

• To collaboratively validate a microplate receptor binding assay (RBA) for quantifying paralytic shellfish toxins (PST) in shellfish.
• To assess the RBA's performance against established methods, including the mouse bioassay and HPLC.
• To determine the suitability of the RBA for routine monitoring of PST levels, especially near regulatory limits.

Main Methods:

• An interlaboratory study involving nine laboratories from six countries.
• Analysis of 21 naturally contaminated shellfish homogenates using the RBA.
• Comparison of RBA results with those from the mouse bioassay (AOAC Method 959.08) and precolumn oxidation HPLC (AOAC Method 2005.06).

Main Results:

• The RBA demonstrated good correlation with both the mouse bioassay (r(2)=0.84) and HPLC (r(2)=0.92).
• The assay showed no false negatives relative to the 800 µg STX diHCl equiv./kg regulatory limit.
• Interlaboratory relative standard deviation (RSDR) was 33.1% (28.7% after removing one lab), and intralaboratory RSDr was 25.1%.

Conclusions:

• The microplate receptor binding assay (RBA) is a suitable method for the routine determination of PST in shellfish.
• The RBA provides a reliable measure of composite PST toxicity, comparable to the mouse bioassay.
• This assay offers a valuable alternative for monitoring shellfish safety and compliance with regulatory standards.