Triple immunochromatographic test system for detection of priority aquatic toxins in water and fish

Aquatic toxins are a group of toxic compounds produced by several types of freshwater and marine algae and cyanobacteria and transported through the food chains of water bodies. Potential contamination of aquaculture products (raw and processed fish and seafood) with aquatic toxins requires the use of efficient screening methods for their control. In this study, a multiplex immunochromatographic test system for the simultaneous detection of three aquatic toxins—phycotoxins domoic acid (DA) and okadaic acid (OA), and cyanotoxin microcystin-LR (MC-LR)—is for the first time developed. For this, a competitive indirect immunochromatographic analysis (ICA) based on gold-labeled secondary antibodies was carried out. The LODs/cutoffs/working ranges of the ICA were 0.05/0.3/0.07–0.29, 1.3/100/3.2–58.2, and 0.1/2.0/0.2–1.1 ng/mL for MC-LR, DA, and OA, respectively. The assay duration was 18 min. The developed test system was used to analyze water samples from natural sources (salt and fresh water) and fish samples. For sample preparation of water, simple dilution with a buffer was proposed; for fish samples, methanol–water extraction was utilized. It was demonstrated that the triple LFIA specifically detected target aquatic toxins with recoveries of 85.0–121.5%. The developed multiplex LFIA can be considered a promising analytical solution for the rapid, easy, and sensitive control of water and food safety. Graphical abstract