Chemometric study of the influence of instrumental parameters on ESI-MS analyte response using full factorial design

Kruve

J. Am. Soc. Mass Spectrom.

et al. 2015

Abstract. For the first time, quantitative electrospray (ESI) ionization efficiencies (IE), expressed as logIE values, obtained on different mass-spectrometric setups (four mass analyzers and four ESI sources) are compared for 15 compounds of diverse properties. The general trends of change of IE with molecular structure are the same with all experimental setups. The obtained IE scales could be applied on different setups: there were no statistically significant changes in the order of ionization efficiency and the root mean of squared differences of the logIE values of compounds between the scales compiled on different instruments were found to be between 0.21 and 0.55 log units. The results show that orthogonal ESI source geometry gives better differentiating power and additional pneumatic assistance improves it even more. It is also shown that the ionization efficiency values are transferable between different mass-spectrometric setups by three anchoring points and a linear model. The root mean square error of logIE prediction ranged from 0.24 to 0.72 depending on the instrument. This work demonstrates for the first time the inter-instrument transferability of quantitative electrospray ionization efficiency data.

Section: E Lectrospray Ionization Mass-spectrometry (Esi/ms) Is Amentioning

confidence: 99%

Transferability of the Electrospray Ionization Efficiency Scale between Different Instruments

Kruve

J. Am. Soc. Mass Spectrom.

et al. 2015

J. Am. Soc. Mass Spectrom.

“…have earlier been shown to influence the analyte response in ESI-MS in certain systems [34]. The effects of these instrumental parameters were assessed by varying the capillary temperature from 100 to 300°C, capillary voltage from −30 V to 30 V and tube lens offset from −30 V to 30 V (see Figure 2S (a)-(c) in the Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Evidence of Molecular Fragmentation inside the Charged Droplets Produced by Electrospray Process

Banerjee

Prakash

Mazumdar

2011

The behavior of the analyte molecules inside the neutral core of the charged droplet produced by the electrospray (ES) process is not unambiguously known to date. We have identified interesting molecular transformations of two suitably chosen analytes inside the ES droplets. The highly stable Ni(II) complex of 1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane (1) that consists of a positive charge at the metal center, and the allyl pendant armed tertiary amine containing macrocycle 3,4,5:12,13,14-dipyridine-2,6,11,15-tetramethyl-1,7,10,16-tetraallyl-1,4,7,10,13,16-hexaazacyclooctadeca-3,13-diene (M 4p ) have been studied by ESI mass spectrometry as the model analytes. We have shown that these two molecules are not representatively transferred from solution to gas phase by ESI; rather, they undergo fragmentation inside the charged droplets. The results indicated that a charged analyte such as 1 was possibly unstable inside the neutral core of the ES droplet and undergoes fragmentation due to the Coulombic repulsion imparted by the surface protons. Brownian motion of the neutral analyte such as M 4p inside the droplet, on the other hand, may lead to proton attachment on interaction with the charged surface causing destabilization that leads to fragmentation of M 4p and release of resonance stabilized allyl cations from the core of the droplet. Detailed solvent dependence and collision-induced dissociation (CID) studies provided compelling evidences that the fragmentation of the analytes indeed occurs inside the charged ES droplets. A viable model of molecular transformations inside the ES droplet was proposed based on these results to rationalize the behavior of the analyte molecules inside the charged ES droplets.

Expert Review of Proteomics

“…As the number of runs in this approach is exponential in the number of experimental factors, it is only feasible for small design problems. Nonetheless, it has been successfully used, for instance by [70].…”

Section: Fixed Design Methodsmentioning

confidence: 99%

Designing biomedical proteomics experiments: state-of-the-art and future perspectives

Maes

Kelchtermans

Bittremieux

et al. 2016

With the current expanded technical capabilities to perform mass spectrometry-based biomedical proteomics experiments, an improved focus on the design of experiments is crucial. As it is clear that ignoring the importance of a good design leads to an unprecedented rate of false discoveries which would poison our results, more and more tools are developed to help researchers designing proteomic experiments. In this review, we apply statistical thinking to go through the entire proteomics workflow for biomarker discovery and validation and relate the considerations that should be made at the level of hypothesis building, technology selection, experimental design and the optimization of the experimental parameters.