Evaluation of gas chromatography for the separation of a broad range of isotopic compounds

Thakur, Nimisha; Aslani, Saba; Armstrong, Daniel W.

doi:10.1016/j.aca.2021.338490

Cited by 11 publications

(2 citation statements)

References 42 publications

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“…In cases where mass spectrometry is blind to mass differences, such as when isotopic labels are present on different groups within the same molecule (e.g., 13 CH 3 CN vs CH 3 13 CN), these changes are easily detectable by a shift in rotational frequencies because the 3D mass distribution is different between these species . Gas chromatography can separate a few isotopic compounds, but it is ineffective for a wide range of analytes . Furthermore, MRR can perform quantitative analysis without requiring reference standards; , thus, rotational line intensities can be accurately predicted for a given concentration.…”

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confidence: 99%

“…2 Gas chromatography can separate a few isotopic compounds, but it is ineffective for a wide range of analytes. 3 Furthermore, MRR can perform quantitative analysis without requiring reference standards; 4,5 thus, rotational line intensities can be accurately predicted for a given concentration. These promising virtues of MRR led to the development of a hyphenated gas chromatography-MRR system in 2020.…”

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Direct Construction of Peaks from Free Induction Decay Curves for Gas Chromatography–Molecular Rotational Resonance Spectroscopy without Fourier Transforms

2022

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The concept of coupling gas chromatography with molecular rotational resonance spectroscopy (GC-MRR) was introduced in 2020, combining the separation capabilities of GC with the unparalleled specificity of MRR. In this study, we address the challenge of the high data throughput of MRR spectrometers, as GC-MRR spectrometers can generate thousands to millions of data points per second. In the previous GC-MRR studies, a free induction decay (FID) measurement was Fourier transformed to generate each point on the chromatogram. Such extensive calculations limit the performance, sensitivity, and speed of GC-MRR. A direct approach is proposed here to extract peak intensity from FID using the Gram–Schmidt vector orthogonalization method. First, analyte-free FIDs are used to construct a basis set representing the instrument’s background noise, and then the remaining FIDs are orthogonalized to this fixed basis set. Each FID yields a single intensity value after Gram–Schmidt orthogonalization. The magnitude of the orthogonalized analyte FID is the signal intensity plotted in the chromatogram. This approach is computationally much faster (up to 10 times) than the conventional Fourier transform algorithm, is at least as sensitive as the FT algorithm, and maintains or improves the chromatographic peak shape. We compare the sensitivity, linearity, and chromatographic peak shapes for the Fourier transform and Gram–Schmidt approaches using both synthetically generated FIDs and instrumental data. This approach would allow the summed peak intensity to be displayed essentially in real-time, following which identified peaks can be further investigated to identify and quantify the species associated with each.

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Direct Construction of Peaks from Free Induction Decay Curves for Gas Chromatography–Molecular Rotational Resonance Spectroscopy without Fourier Transforms

2022

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Isotope-labeling in situ derivatization and HS-SPME arrow GC–MS/MS for simultaneous determination of fatty acids and fatty acid methyl esters in aqueous matrices

Tintrop,

Lieske-Overgrand,

Wickneswaran

et al. 2023

Anal Bioanal Chem

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Fatty acids (FAs) and fatty acid methyl esters (FAMEs) co-occur in many samples, and analysis of both substance classes is frequently of high interest. To this end, this study introduces the first method for simultaneous determination of FAs and FAMEs including fully automated solvent-free solid-phase microextraction (SPME) arrow headspace extraction combined with isotope-labeling in situ FA derivatization with deuterated methanol (CD3OD). By using the chromatographic isotope effect (ΔRt = 0.03 min) and the + 3 m/z mass shift, FAs can be selectively differentiated from the FAMEs during gas chromatography tandem-mass spectrometry (GC–MS/MS) operated in the multiple reaction monitoring (MRM) aquisition mode. Additionally, an approach is presented to predict the retention times of deuterated compounds. Optimization of the derivatization conditions was accomplished by design of experiments and found to be 20 min, 50 °C, 4 v/v% CD3OD, and pH 2.1. During method validation, FAs and FAMEs were calibrated in different concentration ranges by standard addition in five real matrices and ultrapure water leading to good linearities and method detection limits for FAs ranging from 1–30 µg L−1 and for FAMEs from 0.003–0.72 µg L−1. FAs and FAMEs were detected in real samples from surface water, wastewater treatment plant effluent, and three different bioreactor samples and could be quantified in concentrations ranging from 2–1056 µg L−1 for FAs and 0.01–14 µg L−1 for FAMEs. Graphical Abstract

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Ionic liquids as gas chromatography stationary phases

Aslani

Armstrong

2022

Ionic Liquids in Analytical Chemistry

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Evaluation of gas chromatography for the separation of a broad range of isotopic compounds

Cited by 11 publications

References 42 publications

Direct Construction of Peaks from Free Induction Decay Curves for Gas Chromatography–Molecular Rotational Resonance Spectroscopy without Fourier Transforms

Direct Construction of Peaks from Free Induction Decay Curves for Gas Chromatography–Molecular Rotational Resonance Spectroscopy without Fourier Transforms

Isotope-labeling in situ derivatization and HS-SPME arrow GC–MS/MS for simultaneous determination of fatty acids and fatty acid methyl esters in aqueous matrices

Ionic liquids as gas chromatography stationary phases

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