Stable isotope dilution assays in mycotoxin analysis

Abstract

The principle and applications of stable isotope dilution assays (SIDAs) in mycotoxin analysis are critically reviewed. The general section includes historical aspects of SIDAs, the prerequisites and limitations of the use of stable isotopically labelled internal standards, and possible calibration procedures. In the application section actual SIDAs for the analysis of trichothecenes, zearalenone, fumonisins, patulin, and ochratoxin A are presented. The syntheses and availability of labelled mycotoxins for use as internal standards is reviewed and specific advances in food analysis and toxicology are demonstrated. The review indicates that LC-MS applications, in particular, require the use of stable isotopically labelled standards to compensate for losses during clean-up and for discrimination due to ion suppression. As the commercial availability of these compounds continues to increase, SIDAs can be expected to find expanding use in mycotoxin analysis.

Advanced LC–MS-based methods to study the co-occurrence and metabolization of multiple mycotoxins in cereals and cereal-based food

“…Moreover, chromatographic shifts caused by the isotope effect are more common in the case of deuterated standards than in the case of 13 C-and 15 N-labeled ones. Therefore, 13 O and 2 H labeling are less common in mycotoxin quantification using SIDA [61].…”

LC-MS/MS multi-analyte method for mycotoxin determination in food supplements

“…Thus, one internal standard cannot compensate for these effects but a chemically similar and co-eluting compound is required for each analyte. An approach is the addition of isotopically labelled standard (Rychlik and Asam 2008). The use of these substances is useful for the correction of the signal deviation because they have the same chemical properties and the same retention times as the non-labelled substances.…”

Evaluation of minimal 13C-labelling for stable isotope dilution in organic analysis

“…Based on this principle, IDMS results are not affected by analyte losses, low recoveries or matrix effects and therefore, IDMS has been considered as a primary method directly traceable to the International System of Units for the quantity 'amount of substance' or mole. Also, it is currently the technique of choice in many intercomparison exercises or certifications of reference materials by National Metrology Institutes 1 and it has been widely applied in different analytical fields: elemental 2 and organic analysis, 3 elemental speciation 4 and bioanalytical chemistry 5 (particularly in the field of quantitative proteomics 6 ).…”

“…2,4 However, organic isotope dilution analysis traditionally uses a calibration graph that is prepared using the labelled analyte as internal standard. 3 This calibration graph is linear when there is no mass overlap between the labelled and unlabelled analyte and its slope is normally determined experimentally as it depends on the isotopic composition of both the analyte and its labelled analogue as well as on possible isotopic effects during sample preparation. Therefore, the labelled compound in organic isotope dilution is usually selected to provide no mass overlap with the unlabelled analogue.…”

“…For this purpose, a significant mass difference of at least 3 mass units is normally recommended for molecules containing between 10 and 20 carbon atoms. 3 However, when multiple labelling of a molecule is performed, differences in its physicochemical properties in comparison with the natural abundance compound have been observed. [8][9][10][11] This is particularly true with deuterated compounds, because of slightly different hydrogen bonding capabilities, resulting in slightly different extraction and derivatisation yields from those observed for the natural abundance compounds.…”