Toxin Screening in Phytoplankton:  Detection and Quantitation Using MALDI Triple Quadrupole Mass Spectrometry

Abstract

The investigation of a MALDI triple quadrupole instrument for the analysis of spirolide toxins in phytoplankton samples is described in this study. A high-frequency (kHz) laser was employed for MALDI, generating a semicontinuous ion beam, thus taking advantage of the high duty cycle obtained in sensitive triple quadrupole MRM experiments. Initially, several experimental parameters such as type of organic matrix and concentration, solvent composition, and matrix-to-analyte ratio were optimized, and their impact on sensitivity and precision of the obtained ion currents for a reference spirolide, 13-desmethyl-C, was studied. In all quantitative experiments, excellent linearities in the concentration range between 0.01 and 1.75 microg/mL were obtained, with R2 values of 0.99 or higher. The average precision of the quantitative MALDI measurements was 7.4+/-2.4% RSD. No systematic errors were apparent with this method as shown by a direct comparison to an electrospray LC/MS/MS method. Most importantly, the MALDI technique was very fast; each sample spot was analyzed in less than 5 s as compared to several minutes with the electrospray assay. To demonstrate the potential of the MALDI triple quadrupole method, its application to quantitative analysis in several different phytoplankton samples was investigated, including crude extracts and samples from mass-triggered fractionation experiments. 13-Desmethyl spirolide C was successfully quantified in these complex samples at concentration levels from 0.05 to 90.4 microg/mL (prior to dilution to have samples fall within the dynamic range of the method) without extensive sample preparation steps. The versatility of the MALDI triple quadrupole method was also exhibited for the identification of unknown spirolide analogues. Through the use of dedicated linked scan functions such as precursor ion and neutral loss scans, several spirolide compounds were tentatively identified directly from the crude extract, without the usual time-consuming chromatographic preseparation steps. Moreover, high-quality CID spectra were obtained for low-abundant spirolides present in the phytoplankton samples.

Biomedical application of MALDI mass spectrometry for small‐molecule analysis

“…Matrix-assisted laser desorption/ionization (MALDI)-triple quadrupole MS has been used for the analysis of several spirolide toxins in phytoplankton (Sleno and Volmer, 2005b). Samples were extracted in methanol, and LC fractionated.…”

Electron paramagnetic resonance and mass spectrometry: Useful tools to detect ultraviolet light induced skin lesions on a molecular basis – A short review

“…However, Sleno and Volmer recently quantified marine toxins by MALDI-MS and achieved results comparable to HPLC-ESI-MS/MS experiments [67].…”

Development of a Combined Standard Additions/Internal Standards Method to Quantify Residual PEG in Ethoxylated Surfactants by MALDI TOFMS

“…Despite these challenges, there have been a few reports of successful application of MALDI to quantitative problems in biotechnology, such as low mass peptides (i.e., G500 Da) [14][15][16], larger proteins [17,18], food oligosaccharides [19], anthocyanins in red wine [20], spirolide toxins in phytoplankton samples [21], ribonucleic acids (RNAs), and post-transcriptionally modified nucleosides [22]. There have been a few isolated reports of successful quantitation in problems involving synthetic polymers.…”