Analytical Methods for Anatoxin-a Determination: A Review

Abstract

Anatoxin-a (ATX-a) is a potent neurotoxin produced by several species of cyanobacteria whose exposure can have direct consequences, including neurological disorders and death. The increasing prevalence of harmful cyanobacterial blooms makes the detection and reliable assessment of ATX-a levels essential to prevent the risk associated with public health. Therefore, the aim of this review is to compile the analytical methods developed to date for the detection and quantification of ATX-a levels alone and in mixtures with other cyanotoxins and their suitability. A classification of the analytical methods available is fundamental to make an appropriate choice according to the type of sample, the equipment available, and the required sensitivity and specificity for each specific purpose. The most widely used detection technique for the quantification of this toxin is liquid chromatography-tandem mass spectrometry (LC-MS/MS). The analytical methods reviewed herein focus mainly on water and cyanobacterial samples, so the need for validated analytical methods in more complex matrices (vegetables and fish) for the determination of ATX-a to assess dietary exposure to this toxin is evidenced. There is currently a trend towards the validation of multitoxin methods as opposed to single-ATX-a determination methods, which corresponds to the real situation of cyanotoxins' confluence in nature.

Keywords: analytical methods; anatoxin-a; cyanotoxins; parameter validation.

Figure 1

Structures of (A) ATX-a and (B) HATX-a and their respective derivatives.

Figure 2

% of publications focused on determination of ATX-a alone or in combination with other cyanotoxins in relation to years of publication.

Figure 3

Techniques employed for determination of ATX-a alone or in combination with other cyanotoxins. ELISA: enzyme-linked immunosorbent assay; TLC: thin-layer chromatography; UV: ultraviolet; FLD: fluorescence detection; MS: mass spectrometry; ECD: electron capture detector; MS/MS: tandem mass spectrometry; HRMS: high-resolution mass spectrometry: HRMS/MS: high-resolution mass spectrometry tandem mass spectrometry.

Figure 4

Matrices of the samples employed for the determination of ATX-a alone or in combination with other cyanotoxins.

Figure 5

Advantages (green) and disadvantages (red) of the methods developed for ATX-a analysis. ELISA: enzyme-linked immunosorbent assay; HPLC-FLD: high-performance liquid chromatography coupled to fluorescence detection; LC-MS/MS: liquid chromatography–tandem mass spectrometry.