Quantitative analysis with modern bioanalytical mass spectrometry and stable isotope labeling

Abstract

The invention of new ionization techniques namely electrospray ionization and matrix-assisted laser desorption/ionization combined with the development of novel mass spectrometer analyzers and evolving isotope-ratio mass spectrometry have fueled the presence and use of modern mass spectrometric methodologies in many bioanalytical laboratories. Consequently, over the past two decades, a steadily increasing number of quantitative methods employing stable isotope labeling techniques have been reported, including prominent examples of methods to determine differential expression of proteins in disease studies, new-born screening for metabolic disorders, and tracing drugs or dietary compounds and their respective metabolites. Labeling biomolecules for quantitative studies using mass spectrometry has several challenges, including potentially insufficient labeling efficiency, ionization suppression, chromatographic separation of labeled and non-labeled compounds, and isotope exchange with the environment. It is not surprising that method development to minimize or eliminate existing limitations represents a very active and dynamic research area.

Interferences and contaminants encountered in modern mass spectrometry

“…MS related techniques are now the preferred and well-established methods for protein identification [37] and quantification [38]. The complexity of biological samples requires extensive purification and separation methodologies, not only to remove non-proteinaceous components but also to address present proteins that are not of interest [39,40].…”

Peptide and Protein Drug Analysis by MS: Challenges and Opportunities for The Discovery Environment

“…Generally, 'quantitation' in a proteomics sense involves 'differential quantitation' utilizing a limited number of sample pools, generally correspond ing to changes in a global aspect of the target system (e.g., wildtype vs mutant or normal vs pulldown). Hence, several alternative strate gies exist that involve using any of a number of labeling reagents [24] or even labelfree quantita tion [25]. However, most of these strategies are not scalable to the extent required of a discov ery environment (SISCAPA potentially being an exception) [22].…”

(Bio)chemical Labelling Tools for Studying Absorption & Metabolism of Dietary Phenols - An Overview

“…They are metabolized by the intestinal bacteria to the mammalian lignans enterolactone and enterodiol [9]. More recently, with the development of mass spectrometric analytical tools, the use of stable isotopes has become very popular [18][19][20]. On the other hand resveratrol is of much more restricted food distribution [14].…”