An enhanced LC‐MS/MS method for microcystin‐LR in lake water

Abstract

A LC-MS/MS method with enhanced sensitivity and specificity was established for monitoring microcystin-LR (MC-LR) in drinking water supplies in southern Taiwan. The enhanced sensitivity was achieved by the selection of a doubly charged MC-LR as the precursor ion to result in an multiple reaction monitoring (MRM) pair ions of m/z 498.6 --> 135.0. Using this ion pair, a record low detection limit of 2 pg was achieved on column, found in the available literature. A sample preparation method involving C8 solid-phase extraction gave satisfactory recoveries of the analyte. Nodularin, with structural similarity to MC-LR, was used as an internal standard to minimize matrix effects of water samples collected from six different water reservoirs in southern Taiwan, where MC-LR was detected at sub-ppb levels in all the reservoirs. The best precision and accuracy of this method were found with samples prepared to contain MC-LR at 0.1 and 1 microg l(-1). This new method requires considerably smaller water sample volumes because of enhanced quantification sensitivity and hence reduces the time needed for analysis. It should serve as a useful example for method development for monitoring other members of the microcystin family in drinking water supplies.

Integrated Identification and Quantification of Cyanobacterial Toxins from Pacific Northwest Freshwaters by Liquid Chromatography and High-resolution Mass Spectrometry

“…The limits of detection and quantification (LODs, LOQs) were evaluated based on signal-to-noise ratio; the criterions of three and ten standard deviations were adopted for LOD and LOQ, respectively. LODs and LOQs of these toxins were between 0.5 ng/L and 50 ng/L, comparable to LODs previously reported for LC-MRM-based methods [57, 58]. The standard curves were linear (r > 0.998) over the concentration range of 0.5 ng/L to 5 μg/L for toxins spiked to blank freshwater.…”

Simultaneous quantification of microcystins and nodularin in aerosol samples using high‐performance liquid chromatography/negative electrospray ionization tandem mass spectrometry

“…Reversed‐phase HPLC coupled with photodiode array UV detection (DAD) has been used to identify a variety of MCs, even if is recognised that mass spectrometry detection is more specific and sensitive . Modern LC/MS protocols for quantitative analysis are usually based on the reversed‐phase separation coupled through an electrospray ionization (ESI) source to a single or triple quadrupole MS instrument, obtaining pg per injection values as typical detection limits . The aim of this study was to develop a new sensitive method to simultaneously quantify seven cyanobacterial toxins (microcystin LA, LR, LF, LW, LY, YR and nodularin) in the aerosol samples.…”

“…Little research exists on these toxins in the atmospheric environment. [5,6] In response to the need to monitor water sources relative to the proposed World Health Organization (WHO) drinking water guidelines, many techniques were developed to detect and quantify cyanobacterial toxins in water [7][8][9][10][11][12][13] and other matrices such as tissue, [9,[14][15][16] plasma, [17] or sediment. [18] Only a few studies in the literature [5,6] report the investigation of cyanotoxins in aerosol samples, and even less is known regarding aerosol contamination and human exposure.…”

“…To maximize ionization, alkaline conditions were used for the chromatographic separation, obtaining good sensitivity, good chromatographic resolution and detection limits similar to or lower than the ones reported in literature using a positive ionization source. [10,14,17,[22][23][24] The analytical procedure was optimized for aerosol sample treatment so as to improve recovery and accuracy.…”

DISTRIBUTION OF OLIGOPEPTIDE CHEMOTYPES OF THE CYANOBACTERIUM PLANKTOTHRIX AND THEIR PERSISTENCE IN SELECTED LAKES IN FENNOSCANDIA1

“…The screening of cyanobacterial biomass for oligopeptides by LC–MS/MS takes advantage of the high sensitivity of the instruments involved. Typical detection limits are in the magnitude of picograms on column (Li et al. 2006); that is, a conservative estimate of the limit of detection of the above screening method for our samples is 1 ng oligopeptide per mg Planktothrix sp.…”