Comparative Analysis of Microcystin Prevalence in Michigan Lakes by Online Concentration LC/MS/MS and ELISA

Abstract

Fast and reliable workflows are needed to quantitate microcystins (MCs), a ubiquitous class of hepatotoxic cyanotoxins, so that the impact of human and environmental exposure is assessed quickly and minimized. Our goal was to develop a high-throughput online concentration liquid chromatography tandem mass spectrometry (LC/MS/MS) workflow to quantitate the 12 commercially available MCs and nodularin in surface and drinking waters. The method run time was 8.5 min with detection limits in the low ng/L range and minimum reporting levels between 5 and 10 ng/L. This workflow was benchmarked by determining the prevalence of MCs and comparing the Adda-ELISA quantitation to our new workflow from 122 samples representing 31 waterbodies throughout Michigan. The frequency of MC occurrence was MC-LA > LR > RR > D-Asp3-LR > YR > HilR > WR > D-Asp3-RR > HtyR > LY = LW = LF, while MC-RR had the highest concentrations. MCs were detected in 33 samples and 13 of these samples had more than 20% of their total MC concentration from MCs not present in US Environmental Protection Agency (US EPA) Method 544. Furthermore, seasonal deviations between the LC/MS/MS and Adda-ELISA data suggest Adda-ELISA cross-reacts with MC degradation products. This workflow provides less than 24-h turnaround for quantification and also identified key differences between LC/MS/MS and ELISA quantitation that should be investigated further.

A Mini-Review on Detection Methods of Microcystins

“…Besides, the developed paper spray ionization method coupled with a time of flight (TOF) MS and a filter-feeder organism coupled with matrix-assisted laser desorption ionization-TOF MS (MALDI-TOF MS) were found to yield effective MCs determination in various water samples [ 83 , 129 ]. It is worth knowing that the high throughput method based on on-line SPE coupled to LC–quadrupole TOF resolution MS (on-line SPE-LC-QToF HRMS) (LOD between 0.004 and 0.01 µg/L), on-line SPE-UHPLC-HRMS (LOD between 8 and 53 ng/L), online SPE-UHPLC-MS/MS (LOD between 0.1 and 0.5 µg/kg) and online concentration LC/MS/MS workflow (LOD between 0.6 and 3.8 ng/L) also successfully detected different variants of MC in water samples [ 34 , 96 , 101 , 102 ]. The matrix solid-phase dispersion (MSPD) followed by HPLC/MS/MS (MSPD-HPLC-MS/MS) (LOD 13.0 μg/kg (dw)) and SPE-UPLC-MS/MS (LOD 0.06–0.42 ng/g f.w) were also used to determine trace levels of MCs in various vegetables [ 142 ].…”

“…Although LC/MS detectors are limited by equipment cost, they are becoming cheaper, and thus, a water monitoring laboratory with a limited budget may soon be able to purchase them for routine analysis. It is of interest that MS can be used to separate, quantify and present potential for high throughput towards MCs detection [ 101 , 102 , 103 , 122 ]. With the availability of suitable analytical standards, the technique can be used to confirm, identify and quantify variants of MC in an unknown sample, and regarding method specificity LC/TOF-MS is preferred due to its accurate mass capability [ 83 , 84 , 88 , 103 , 129 ].…”

“…For MS sample enrichment and cleaning, complex preparation is needed due to its level of sensitivity and selectivity [ 34 , 93 , 120 ]. Further, though MS/MS detection is more sensitive and selective, standard reference is needed to detect the optimal ion transitions of the analyses and for quantitative purposes [ 101 , 102 , 103 , 115 ].…”

Analysis of multiclass cyanotoxins (microcystins, anabaenopeptins, cylindrospermopsin and anatoxins) in lake waters using on-line SPE liquid chromatography high-resolution Orbitrap mass spectrometry

“…The use of on-line SPE has proven effective in past studies aiming at including diverse cyanotoxins in a single high-throughput method, without signicantly affecting sensitivity. [37][38][39][40][41][42][43] The methods proposed earlier can still be improved by expanding the scope of targeted cyanotoxins for a wider screening. Some studies have also explored the possibility of using high-resolution MS to quantify known cyanotoxins and identify unknown cyanopeptide variants using LC-QTOF or LC-Orbitrap.…”

Perspectives on Harmful Algal Blooms (HABs) and the Cyberbiosecurity of Freshwater Systems

“…and associated toxins (anatoxin-a, saxitoxins, cylindrospermopsin, euglenophycin, etc.) have been observed in a range of freshwater systems (Graham et al, 2010; Foss and Aubel, 2015; Loftin et al, 2016; Birbeck et al, 2019). Today, a critical gap still exists on the relationship between human and animal health impact and the range of conditions under which the toxins are produced and the resulting range of toxicities (~50 to >5,000 μg kg −1 ) (Chorus and Bartram, 1999).…”