Enhanced Sample Preparation for Quantitation of Microcystins by Matrix‐Assisted Laser Desorption/Ionisation–Time of Flight Mass Spectrometry

Abstract

The study demonstrates that with different sample preparation methods and modern instrumentation, large numbers of samples can be analysed rapidly for MCs at low cost.

Rapid quantitative analysis of microcystins in raw surface waters with MALDI MS utilizing easily synthesized internal standards

“…Previous work on the quantitative use of MALDI-TOF for MC analysis showed that the best sensitivity was obtained when nodularin was used as IS (Howard and Boyer, 2007; Puddick et al, 2011). This is probably due to the high similitude of nodularin with the common structure of MCs.…”

“…To date, MALDI-TOF MS mostly has been utilized qualitatively to identify MC variants in cyanobacterial colonies and surface water blooms (Erhard et al, 1997; Ferranti et al, 2011; Welker et al, 2002), and its use for MC quantification is rather recent (Howard and Boyer, 2007; Puddick et al, 2011). Quantitative detection by MALDI-TOF based on peak response has poor reproducibility, mainly due to spot-to-spot variability in crystal formation (Duncan et al, 2008; Szajli et al, 2008).…”

“…In the initial report of a quantitative MALDI-TOF application for MCs (Howard and Boyer, 2007), three potential internal standards were assayed, and the best method detection limit (MDL) for MC-LR was obtained with nodularin (a pentapeptide cyanotoxin with similar basic ring structure to microcystins), which outperformed a [15N]10-isotopomer of microcystin-YR and the peptide hormone angiotensin I. More recently, Puddick et al, in order to reduce the cost of the analysis, used angiotensin I as internal standard in combination with different sample preparation techniques, but being a linear peptide, angiotensin as IS did not attain the MDL values previously obtained with nodularin (Puddick et al, 2011). This highlights the importance of using internal standards that resemble the physicochemical properties of the target compound.…”

Quantitative Characterization of Tissue Globotetraosylceramides in a Rat Model of Polycystic Kidney Disease by PrimaDrop Sample Preparation and Indirect High-Performance Thin Layer Chromatography–Matrix-Assisted Laser Desorption/Ionization-Time-of-Flight-Mass Spectrometry with Automated Data Acquisition

“…For relative quantitation of Gb4Cer from PKD kidneys, six spots were prepared for each sample. Spectra with resolution >2000 were summed up and 3500 laser shots at 35 were accumulated with 4 × 25 shots per position in a random walk.…”

“…Inhomogeneous cocrystallization of matrix and analytes and formation of “sweet spots” in standard dried-droplet sample preparation is arguably the biggest hurdle for development of automated MALDI-TOF-MS applications. Alternative crystallization methods, such as fast evaporation, , two-layer, or sandwich crystallization, , have been successfully described for proteomic studies and intact cell profiling, − but homogeneous lipid-sample crystallization methods for automated MS work flows have not been assessed so far. Careful matrix optimization often leads to significant improvements in sensitivity of lipid detection .…”