Predicting ESI/MS Signal Change for Anions in Different Solvents

Abstract

LC/ESI/MS is a technique widely used for qualitative and quantitative analysis in various fields. However, quantification is currently possible only for compounds for which the standard substances are available, as the ionization efficiency of different compounds in ESI source differs by orders of magnitude. In this paper we present an approach for quantitative LC/ESI/MS analysis without standard substances. This approach relies on accurately predicting the ionization efficiencies in ESI source based on a model, which uses physicochemical parameters of analytes. Furthermore, the model has been made transferable between different mobile phases and instrument setups by using a suitable set of calibration compounds. This approach has been validated both in flow injection and chromatographic mode with gradient elution.

Impact of anthropogenic and biogenic sources on the seasonal variation in the molecular composition of urban organic aerosols: a field and laboratory study using ultra-high-resolution mass spectrometry

“…Field deployments of an aerosol mass spectrometer (AMS, Canagaratna et al, 2007) at several European stations have revealed a large impact of primary wood-burning emissions on OA (e.g. between 11 % and 59 % in Switzerland), while primary traffic emissions have a smaller contribution (4 %-14 %) (Lanz et al, 2010;Gilardoni et al, 2011;Daellenbach et al, 2017). The results are consistent with radiocarbon measurements (Zotter et al, 2014a), showing that during extreme winter pollution episodes non-fossil organic carbon may account for up to 97 % of organic carbon (OC) at Alpine valley sites (Magadino -83 %, San Vittore -97 %) and 74 % at an urban background site in Zurich and are also associated with levoglucosan, a pyrolysis product of cellulose.…”

Influence of the amino acid composition on the ionization efficiencies of small peptides

“…The ionization efficiency of a compound is dependent on the physicochemical properties of the compound (its acid-base properties, hydrophobicity, volume, etc. ), [4][5][6][7][8][9] solvent used for analysis, [10][11][12] sample matrix, 13 etc. In order to better understand the factors influencing the signal of the analyte, it is important to consider the different ionization mechanisms.…”

“…Additionally, peptides containing disulfide bonds are expected to obtain lower charge states as basic residues are less accessible to solvent. 26 Our group has previously focused on predicting the ionization efficiencies of small molecules (mostly compounds with the molecular weight below 400 Da), 4,11,27 which ionize via IEM. The physicochemical parameters for the model have been calculated by combining density functional theory (DFT) and COnductor like Screening MOdel for Real Solvents (COSMO-RS) calculations.…”

Semi‐quantitative non‐target analysis of water with liquid chromatography/high‐resolution mass spectrometry: How far are we?

“…Wu et al have established a quantitative model aiming to account for solvent changes in LC/ESI‐MS for 25 organic acids via five parameters: hydrogen bond acidity, HOMO energy, number of hydrogen bond donating groups, the ratio of organic solvent in the mobile phase, and the polar solvent accessible area. We have lately proposed using multilinear calibration in combination with a simple system of calibration compounds to evaluate the importance of each physicochemical parameter specific to the instrument and solvent used for the analysis . This approach has allowed us to achieve an accuracy of 3.5 mean‐mismatch between the predicted and actual concentration.…”

“…68 to the instrument and solvent used for the analysis. 70 This approach has allowed us to achieve an accuracy of 3.5 mean-mismatch between the predicted and actual concentration. However, this approach has so far been used only in ESI negative mode and it is not yet available as a convenient software package compatible with other data processing methods used in non-target analysis.…”