The goal of this work is to describe more recent developments in the quantitative mass spectrometry and to illustrate how our new model equations based on the stochastic dynamics relate to the determining the 3D molecular and electronic structures of analytes. It is aimed at researchers in Chemistry who would like to find out about what is going on in mass spectrometric methodological contributions more recently. The work could also be used to MSc and PhD students in the field of Chemistry, in particular, highlighting the ‘Analytical chemistry’, ‘Physico–chemistry’ and/or ‘Computational and theoretical chemistry’, respectively.
Table of Content
Introduction
1. Experimental
1.1. Synthesis
1.2. Analytical instrumentation and methods
1.2.1. Mass spectrometric measurements
1.2.2. Sample preparation for the MALDI-MS measurements
1.3. Theory/Computations
1.3.1. Stochastic dynamics
1.3.2. Chemometrics
1.3.3. Computational quantum chemistry
2. Results and discussion
2.1. Experimental MALDI mass spectrometric data – qualitative analysis
2.2. Experimental MALDI mass spectrometric data – quantitative analysis
2.3. MALDI mass spectrometric method performances
2.4. Experimental electrospray ionization mass spectrometric data – quantitative analysis
2.5. Correspondence between diffusion parameters obtained on the base on stochastic dynamics and current monitoring method
3. Theoretical data
Conclusion
Research Objectives and Core Themes
The primary objective of this work is to establish a robust quantitative framework for Matrix-Assisted Laser Desorption/Ionization (MALDI) mass spectrometry by applying stochastic dynamics. The research addresses the challenge of accurately determining 3D molecular and electronic structures of analytes by modeling the temporal behavior of mass spectrometric signal intensities, thereby overcoming issues related to sample heterogeneity and non-uniform distribution.
- Application of stochastic dynamics to quantify MALDI-MS and ESI-MS signal intensities.
- Development of new model equations derived from the Box-Müller method to treat MS intensity as a random variable.
- Comparative analysis of analyte quantification using single crystal and polycrystalline sample preparations.
- Integration of high-accuracy quantum chemical modeling (DFT, ab initio) to correlate theoretical diffusion parameters with experimental data.
- Validation of the proposed methodology through comprehensive chemometric analysis and statistical correlation.
Excerpt from the Book
1.2.1. Mass spectrometric measurements
Mass spectrometric measurements were carried out by TSQ 7000 instrument (Thermo Fisher Inc., Rockville, MD, USA). A triple quadruple mass spectrometer (TSQ 7000 Thermo Electron, Dreieich, Germany) equipped with an ESI 2 source were used for ESI–MS and APCI–MS measurements. The quantification using the lastly mentioned instrument was carried out via a combination of mass detectors (trap, linear ion trap and orbitrap), accumulating spectra for t = 7–30 mins (420–1800 s). The selected reaction monitoring approach was used, where the data were saved as individual files. The relative intensities of the species studied were obtained using QualBrowser software 2.7. The program package ProteoWizard 3.0.11565.0 (2017) was used as well. The mass resolving power R = 98 101. The ESI, atmospheric pressure chemical ionization (APCI) and collision induced dissociation (CID) resolving powers are R = 55 121, 19 341, 15 700, respectively. A standard LTQ Orbitrap XL (Thermo Fisher Inc.) spectrometer was used for MALDI–MS measurements, using the UV laser source at λmax = 337.2 nm. An overall mass range of m/z 100–1000 was scanned simultaneously in the Orbitrap analyzer in presence of inner standard (Figs. 1 and 2; m/z 283). The ImageQuest 1.0.1 program package was used. The extracted MS spectra (without the MS peaks of the inner standard) and processing of the ion chromatograms was performed using AMDIS 2.71 (2012) and SeeMS 3.0.11.565.0 (2017), respectively. The laser energy values were ∈ 14.8–15.5 μJ. The numbers of averaged laser shots lies ∈ 18–80, the MALDI flow rate values were ∈ 25.01–25.08, the corresponding elapsed scan time range lies ∈ 18.0–2.50 s, respectively.
Summary of Chapters
Introduction: Provides an overview of the power of mass spectrometry in qualitative and quantitative analysis while identifying the lack of accurate quantitative models for 3D structural determination.
1. Experimental: Details the chemical synthesis of the analyte, instrumentation specifications for MS and HPLC, and the specific sample preparation techniques used for both MALDI and ESI measurements.
2. Results and discussion: Presents the qualitative and quantitative analysis of experimental MALDI and ESI mass spectrometric data, applying the stochastic dynamics approach and verifying results through chemometric testing.
3. Theoretical data: Connects experimental findings with high-accuracy quantum chemical computations to validate diffusion parameters and reaction energetics via the Arrhenius formalism.
Conclusion: Synthesizes the core findings, confirming the validity of the proposed stochastic model equations across different sample preparations and highlighting the impact on structural analytical chemistry.
Keywords
Stochastic dynamics, mass spectrometry, quantification, MALDI-MS, ESI-MS, diffusion parameters, chemometrics, DFT, molecular modeling, 3D structural determination, ion intensity, signal processing, quantum chemistry, Arrhenius approximation, thermodynamic modeling
Frequently Asked Questions
What is the core focus of this scientific research?
The work focuses on developing a new quantitative methodology for MALDI mass spectrometry by utilizing stochastic dynamics to model the temporal behavior of analyte ion intensities.
What are the primary thematic areas covered?
The research spans analytical chemistry, physical chemistry, and computational/theoretical chemistry, specifically aiming to link experimental MS data with quantum chemical modeling.
What is the central research question?
The central question is whether the MALDI-MS method can effectively serve as a prospective approach for the accurate quantitative analysis of reaction kinetics, diffusion, and 3D structural determination of analytes.
Which scientific methodology is employed?
The study employs stochastic dynamics, specifically the Box-Müller method, alongside non-linear regression, chemometric ANOVA tests, and high-level quantum chemical computations like DFT and ab initio methods.
What does the main body of the work address?
The main body presents experimental results from mass spectrometric measurements, validates these through statistical and theoretical models, and discusses the correlation between experimental diffusion parameters and quantum chemical predictions.
Which keywords best characterize the work?
Key terms include stochastic dynamics, mass spectrometry, quantification, MALDI-MS, ESI-MS, diffusion parameters, and chemometrics.
How does the study handle sample heterogeneity in MALDI-MS?
The study proposes using nonlinear model equations that account for the stochastic nature of random intensity variations caused by sample heterogeneity and non-uniform analyte distribution.
How is the theoretical validation performed?
Validation is achieved by comparing experimental diffusion parameters with those derived from quantum chemical modeling, utilizing the Arrhenius approximation to connect activation enthalpy and diffusion.
What role does the 'current monitoring method' play?
It serves as an independent methodology used to benchmark the diffusion parameters obtained via the new stochastic dynamics approach, demonstrating significant statistical correlation.
- Citar trabajo
- Prof. Dr. Bojidarka Ivanova (Autor), Michael Spiteller (Autor), 2018, Quantification by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry Using An Approach Based On Stochastic Dynamics. Experimental And Theoretical Correspondences, Múnich, GRIN Verlag, https://www.grin.com/document/425061
