Quantitative Analysis of Cyanobacterial Toxins by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

Abstract

Microcystins (MCs) are a growing problem in drinking water supplies worldwide. Common analytical techniques used to determine MC concentrations have several shortcomings, including extensive sample handling and lengthy analysis times. A simple, rapid method for quantitation of MCs by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is presented. Four potential internal standards were tested, including an 15N-labeled MC. For MC-LR in mixed standard solutions, a linear range of 0.11-5.0 microM (R2 = 0.98) was achieved, with a method detection limit (MDL) of 0.015 microM. Matrix effects due to extracted cell components decreased the MC-LR linear range slightly to 0.19-5.0 microM (R2 = 0.99), with MDL = 0.058 microM. Extensive analysis of possible internal standards indicates that nodularin was preferred over [15N]10-microcystin-YR or angiotensin I. The ionization efficiency and analyte-analyte suppression for four MCs of varying polarity are presented; the three polar congeners exhibited good ionization efficiency and acceptable levels of analyte-analyte suppression. These results indicate that MALDI-TOF MS represents a viable alternative for the quantitative measurement of MCs in field samples.

An integrated strategy for rapid and accurate determination of free and cell-bound microcystins and related peptides in natural blooms by liquid chromatography–electrospray-high resolution mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry using both positive and negative ionization modes

“…As a result, all the MCs were simultaneously ionized and a fingerprint of MC presence was provided quickly and easily by the full scan mass spectra. However, the poor spot-to-spot and shot-to-shot reproducibility of analyte signal intensities makes it necessary to use an IS for quantitation [32] but with solid samples was difficult to handle. Therefore, for quantitative analysis, methanolic extracts of lyophilized sestonic fraction were analyzed using LC/ESI-HRMS as chosen method.…”

“…Additionally, electrospray (ESI) recorded in negative ion mode has recently been applied to the analysis of MCs [19][20][21]. In order to have faster methods for toxin analysis: ultra-high performance liquid chromatography (UHPLC) [22][23][24], on-line solid phase extraction (SPE) [25][26][27][28] and direct analysis without prior extraction [29,30] and chromatographic separation [31,32] have been implemented in several works.…”

“…The use of full scan MS approaches employing high-resolution mass spectrometers and accurate mass measurements (AMM) has also strongly emerged as attractive alternative for the analysis of biotoxins [31][32][33][34][35][36][37][38]. Specifically, the application of Orbitrap higher resolution mass analyzer was capable of supporting fairly rapid and reliable identifications of known toxins even when standards were not available [33][34][35][36]38].…”

Molecular characterization of microcystin-producing cyanobacteria from Romanian fresh waters

“…Since the chlorophyll-a and hence the phaeophytin-a content of the samples can be considered to be rather homogeneous, the peak heights of the MCs relative to the phaeophytin-a peak (Fig. 1) can be taken as a semiquantitative measure of the relative MC content (Howard & Boyer 2007).…”

Quantitative evaluation of sphingomyelin and glucosylceramide using matrix-assisted laser desorption ionization time-of-flight mass spectrometry with sphingosylphosphorylcholine as an internal standard

“…MALDI-TOF/MS is sensitive and convenient for detecting glycosphingolipids including lysosphingolipids [2][3][4]. It was reported previously that MALDI-TOF/MS is a useful technique for quantitative analysis of biological materials with high sensitivity [5][6][7][8][9][10][11]. Niemann-Pick disease types A and C, and Gaucher diseases are all autosomal recessive inborn errors, sphingolipids storage diseases.…”