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Microcystins (MCs) and nodularins (NODs) exhibit high structural variability, including modifications of the Adda (3S-amino-9S-methoxy-2S,6,8S-trimethyl-10-phenyldeca-4E,6E-dienoic acid) moiety. Variations include 9-O-desmethylAdda (DMAdda) and 9-O-acetylDMAdda (ADMAdda) which, unless targeted, may go undetected. Therefore, reference standards were prepared of [ADMAdda5]MCs and [DMAdda5]MCs, which were analyzed using multiple approaches. The cross-reactivities of the [DMAdda5]- and [ADMAdda5]MC standards were similar to that of MC-LR when analyzed with a protein phosphatase 2A (PP2A) inhibition assay, but were, Graphical abstract Image 1, Highlights • Toxic ADMAdda/DMAdda microcystins (MCs) exhibit low cross-reactivity with Adda ELISA. • A method for oxidative cleavage was expanded to test for ADMAdda/DMAdda MCs. • Two sites of oxidative cleavage of the Adda/DMAdda/ADMAdda were observed. • Oxidation products were identified and analytically tested to quantitate ‘total MCs’.

In the summer of 2012, over 750 dead and dying birds were observed at the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island, Maryland, USA (Chesapeake Bay). Clinical signs suggested avian botulism, but an ongoing dense Microcystis bloom was present in an impoundment on the island. Enzyme-linked immunosorbent assay (ELISA) analysis of a water sample indicated 6000 ng mL −1 of microcystins (MCs). LC-UV/MS analysis confirmed the presence of MC-LR and a high concentration of an unknown MC congener ( m/z 1037.5). The unknown MC was purified and confirmed to be [D-Leu 1 ]MC-LR using NMR spectroscopy, LC-HRMS and LC–MS 2 , which slowly converted to [D-Leu 1 ,Glu(OMe) 6 ]MC-LR during storage in MeOH. Lyophilized algal material from the bloom was further characterized using LC-HRMS and LC–MS 2 in combination with chemical derivatizations, and an additional 24 variants were detected, including MCs conjugated to Cys, GSH and γ-GluCys and their corresponding sulfoxides. Mallard ( Anas platyrhynchos ) livers were tested to confirm MC exposure. Two broad-specificity MC ELISAs and LC–MS 2 were used to measure free MCs, while ‘total’ MCs were estimated by both MMPB (3-methoxy-2-methyl-4-phenylbutyric acid) and thiol de-conjugation techniques. Free microcystins in the livers (63–112 ng g −1 ) accounted for 33–41% of total microcystins detected by de-conjugation and MMPB techniques. Free [D-Leu 1 ]MC-LR was quantitated in tissues at 25–67 ng g −1 (LC–MS 2 ). The levels of microcystin varied based on analytical method used, highlighting the need to develop a comprehensive analysis strategy to elucidate the etiology of bird mortality events when microcystin-producing HABs are present.

In 2016, the Pennsylvania Department of Environmental Protection conducted a limited survey of streams in the Susquehanna River basin in Pennsylvania, USA, to screen for microcystins/nodularins, anatoxin-a (ATX) and homoanatoxin-a (HTX). Testing revealed the presence of HTX in samples collected from the Pine Creek basin, with ATX present at lower levels. Microcystins/nodularins (MCs/NODs) were also tested and found to be concomitant, with NOD-R confirmed present by LC-MS/MS.

In 2013 and 2015, the Pennsylvania Department of Environmental Protection conducted a survey of lotic habitats within the Susquehanna, Delaware, and Ohio River basins in Pennsylvania, USA, to screen for microcystins/nodularins (MCs/NODs) in algae communities and smallmouth bass (Micropterus dolomieu). Periphyton (68 from 41 sites), juvenile whole fish (153 from 19 sites) and adult fish liver (115 from 16 sites) samples were collected and screened using an Adda enzyme-linked immunosorbent assay (ELISA). Samples that were positive for MCs/NODs were further analyzed using LC-MS/MS, including 14 variants of microcystin and NOD-R and the MMPB technique. The ELISA was positive for 47% of the periphyton collections, with NOD-R confirmed (0.7–82.2 ng g−1 d.w.) in 20 samples. NOD-R was confirmed in 10 of 15 positive juvenile whole fish samples (0.8–16.7 ng g−1 w.w.) and in 2 of 8 liver samples (1.7 & 2.8 ng g−1 w.w.). The MMPB method resulted in total MCs/NODs measured in periphyton (2.2–1269 ng g−1 d.w.), juvenile whole fish (5.0–210 ng g−1 d.w.) and adult livers (8.5–29.5 ng g−1 d.w.). This work illustrates that NOD-R is present in freshwater benthic algae in the USA, which has broader implications for monitoring and trophic transfer.

The naturally derived cyanotoxin, cylindrospermopsin (CYN), has been detected in freshwater systems worldwide and poses a threat to human health. The methods for the extraction and detection of this toxin in source water are well documented, but methods for CYN determination in exposed individuals have not been investigated. In this study, the extraction and detection of CYN from two different matrices, serum and urine, was explored. Both serum and urine matrices inherently produce interference with analytical analyses and require extensive clean-up. Methods for extraction of CYN from both matrices were developed and validated using fortified samples. Serum extraction included homogenization followed by protein precipitation and solid phase extraction (SPE). Urine samples were processed using filtration, pH manipulation, and SPE. Analyses using a commercially available enzyme-linked immunosorbent assay (ELISA) and liquid chromatography coupled with mass spectrometry (LC/MS/MS) were assessed. Matrix effects inhibited ELISA's use as a quantitative tool for both matrices. LC/MS/MS was determined to be the most effective and reproducible means to detect and quantify CYN. The method detection limits determined in this study using LC/MS/MS were 0.25 and 0.50 ng mL⁻¹ for serum and urine, respectively. This method can be used to test individuals exposed to blooms of cyanobacteria producing CYN.

Toxigenic cyanobacteria are common components of Florida's surface waters and may pose a threat to their ecology and a risk to human health. The Lake County Water Authority, the Florida Department of Health, the St. Johns River Water Management District, the South Florida Water Management District, and the Lee County Health Department have all recently monitored local waters for cyanotoxins. In 2004, 6 central Florida lakes were sampled monthly for 12 months at centrally located open water sample sites. Toxin data (n = 72 for all toxin analyses) showed that microcystins (0.1–3.6 μg/L) were present in all 12 months; multiple bloom events per lake were observed; bloom concentrations ranged from 5–7,500 μg/L; and blooms occurred throughout the entire year. Cylindrospermopsin, ranging in concentration from 0.05 to 0.2 μg/L, was reported in 22% of all samples analyzed and occurred predominantly between August and December. Anatoxin-a was not reported in 2003/2004 but was identified in 2002/2003 (30%, ...

Paralytic Shellfish Toxins (PSTs) are highly toxic metabolic by-products of cyanobacteria and dinoflagellates. The filamentous cyanobacterium Lyngbya wollei produces a unique set of PSTs, including L . wollei toxins (LWT) 1–6. The accurate identification and quantification of PSTs from Lyngbya filaments is challenging, but critical for understanding toxin production and associated risk, as well as for providing baseline information regarding the potential for trophic transfer. This study evaluated several approaches for the extraction and analysis of PSTs from field-collected L . wollei dominated algal mats. Extraction of PSTs from lyophilized Lyngbya biomass was assessed utilizing hydrochloric acid and acetic acid at concentrations of 0.001–0.1 M. Toxin profiles were then compared utilizing two analysis techniques: pre-column oxidation (peroxide and periodate) High Performance Liquid Chromatography (HPLC) with Fluorescence (FL) detection and LC coupled with Mass Spectrometry (MS). While both acid approaches efficiently extracted PSTs, hydrochloric acid was found to convert the less toxic LWT into the more toxic decarbamoylgonyautoxins 2&3 (dcGTX2&3) and decarbamoylsaxitoxin (dcSTX). In comparison, extraction with 0.1 M acetic acid preserved the original toxin profile and limited the presence of interfering co-extractants. Although pre-chromatographic oxidation with HPLC/FL was relatively easy to setup and utilize, the method did not resolve the individual constituents of the L. wollei derived PST profile. The LC/MS method allowed characterization of the PSTs derived from L. wollei , but without commercially available LWT 1–6 standards, quantitation was not possible for the LWT. In future work, evaluation of the risk associated with L. wollei derived PSTs will require commercially available standards of LWT 1–6 for accurate determinations of total PST content and potency.

The eutrophication of water resources, mainly attributed to antrophogenic activities such as sewage and agricultural runoffs, has led to a worldwide increase in the formation of cyanobacterial harmful algal blooms (Cyano-HABs). Cyano-HABs have the ability to produce and release toxic compounds, commonly known as cyanotoxins, which comprise a potent threat for human and animal health as well as negative economical impacts. This chapter presents an overview on the sources and occurrence of species of cyanobacteria and their association with the production of cyanotoxins throughout the world. The main bloom-forming cyanobacteria that have been detected include Microcystis, Cylindrospermopsis, Anabaena, Aphanizomenon, and Planktothrix. The main cyanotoxins related to these cyanobacteria are microcystins, cylindrospermopsin, anatoxin-a and saxitoxins.

A study of silica-bound proteins used as chiral stationary phases for the optical resolution of benzoyl and dansyl derivatives of several amino acids by liquid chromatography is described. The proteins included bovine serum albumin (BSA), α-acid glycoprotein (AGP), ovalbumin, myoglobin and lactate dehydrogenase as well as two commercially available columns, Resolvosil ® -BSA and EnantioPac (AGP). Pretreatments with organic solvents as well as greater protein coverage increased the selectivity factors, α, of the BSA columns.