Variations in GC–MS Response Between Analytes and Deuterated Analogs

Alzweiri, Muhammed; Khanfar, Mohammad A.; Al‐Hiari, Yusuf

doi:10.1007/s10337-014-2842-2

Cited by 11 publications

(8 citation statements)

References 35 publications

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“…8% of the overall product under condition 1 , assuming that the GCMS response factor is the same for all isotopomers. However, for the related dimethyl nonanedioate, the response factor of the protio form is 1.5× that of the isotopomer containing 6 D atoms in the methyl groups . So, in our study the rate of methoxycarbonylation is only about 5% that of isomerization under conditions 1 (Table ).…”

Section: Isomerizing Carbonylationsmentioning

confidence: 65%

“…However, for the related dimethyl nonanedioate, the response factor of the protio form is 1.5× that of the isotopomer containing 6 D atoms in the methyl groups. 163 So, in our study the rate of methoxycarbonylation is only about 5% that of isomerization under conditions 1 (Table 3). Interestingly, the rates of the two reactions are much more similar at room temperature and 1 bar of CO (conditions 4, Table 3).…”

Section: Mechanistic Considerations For Isomerizing Methoxycarbonylat...mentioning

confidence: 99%

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Magic of Alpha: The Chemistry of a Remarkable Bidentate Phosphine, 1,2-Bis(di-tert-butylphosphinomethyl)benzene

Vondran

Furst

Eastham³

et al. 2021

Chem. Rev.

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The bidentate phosphine ligand 1,2-bis(di-tert-butylphosphinomethyl)benzene (1,2-DTBPMB) has been reported over the years as being one of, if not the, best ligands for achieving the alkoxycarbonylation of various unsaturated compounds. Bonded to palladium, the ligand provides the basis for the first step in the commercial (Alpha) production of methyl methacrylate as well as very high selectivity to linear esters and acids from terminal or internal double bonds. The present review is an overview covering the literature dealing with the 1,2-DTBPMB ligand: from its first reference, its catalysis, including the alkoxycarbonylation reaction and its mechanism, its isomerization abilities including the highly selective isomerizing methoxycarbonylation, other reactions such as cross-coupling, recycling approaches, and the development of improved, modified ligands, in which some tert-butyl ligands are replaced by 2-pyridyl moieties and which show exceptional rates for carbonylation reactions at low temperatures.

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Section: Isomerizing Carbonylationsmentioning

confidence: 65%

Section: Mechanistic Considerations For Isomerizing Methoxycarbonylat...mentioning

confidence: 99%

Magic of Alpha: The Chemistry of a Remarkable Bidentate Phosphine, 1,2-Bis(di-tert-butylphosphinomethyl)benzene

Vondran

Furst

Eastham³

et al. 2021

Chem. Rev.

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show abstract

“…Although this study has concentrated on the carbon isotopes, it should be noted that the behavior might also be seen with nitrogen ( 15 N ~0.37% M + 1) and oxygen ( 18 O ~0.21% M + 2) under appropriate circumstances. Although deuterium labeled compounds are often prepared with many deuterium atoms per molecule, the low abundance ( 2 H ~0.012% M + 1) suggests that other factors such as isotopic fractionation and differential ionization are likely to be more significant sources of error for most deuterated compounds.…”

Section: Resultsmentioning

confidence: 99%

Determining the isotopic abundance of a labeled compound by mass spectrometry and how correcting for natural abundance distribution using analogous data from the unlabeled compound leads to a systematic error

Schenk

Lockley

Elmore

et al. 2016

J. Label Compd. Radiopharm

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When the isotopic abundance or specific activity of a labeled compound is determined by mass spectrometry (MS), it is necessary to correct the raw MS data to eliminate ion intensity contributions, which arise from the presence of heavy isotopes at natural abundance (e.g., a typical carbon compound contains ~1.1% (13) C per carbon atom). The most common approach is to employ a correction in which the mass-to-charge distribution of the corresponding unlabeled compound is used to subtract the natural abundance contributions from the raw mass-to-charge distribution pattern of the labeled compound. Following this correction, the residual intensities should be due to the presence of the newly introduced labeled atoms only. However, this will only be the case when the natural abundance mass isotopomer distribution of the unlabeled compound is the same as that of the labeled species. Although this may be a good approximation, it cannot be accurate in all cases. The implications of this approximation for the determination of isotopic abundance and specific activity have been examined in practice. Isotopically mixed stable-atom labeled valine batches were produced, and both these and [(14) C6 ]carbamazepine were analyzed by MS to determine the extent of the error introduced by the approach. Our studies revealed that significant errors are possible for small highly-labeled compounds, such as valine, under some circumstances. In the case with [(14) C6 ]carbamazepine, the errors introduced were minor but could be significant for (14) C-labeled compounds with particular isotopic distributions. This source of systematic error can be minimized, although not eliminated, by the selection of an appropriate isotopic correction pattern or by the use of a program that varies the natural abundance distribution throughout the correction.

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“…Second, having all deuterated standards is tedious and expensive. Third, deuteration can cause an isotope effect in either chromatography or ionisation efficiency so that the GC-MS signal differs between deuterated and the protiated forms (Alzweiri, Khanfar, & Al-Hiari, 2015;Caban & Stepnowski, 2020;Matucha, Jockisch, Verner, & Anders, 1991;Ripszam, Grabic, & Haglund, 2013).…”

Section: Application To Plant Samplesmentioning

confidence: 99%

Exact mass GC-MS analysis: protocol, database, advantages and application to plant metabolic profiling

Abadie

Lalande

Tcherkez

2022

Preprint

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Plant metabolomics has been used widely in plant physiology, in particular to analyse metabolic responses to environmental parameters. Derivatization (via trimethylsilylation-methoximation) followed by GC-MS metabolic profiling is a major technique to quantify low molecular weight, common metabolites of primary carbon, sulphur and nitrogen metabolism. There are now excellent opportunities for new generation analyses, using high resolution, exact mass GC-MS spectrometers that are progressively becoming relatively cheap. However, exact mass GC-MS analyses for routine metabolic profiling are not common, there is no dedicated available database. Also, exact mass GC-MS is usually dedicated to structural resolution of targeted secondary metabolites. Here, we present a curated database for exact mass metabolic profiling (made of 336 analytes, 1,064 characteristic exact mass fragments) focused on molecules of primary metabolism. We show advantages of exact mass analyses, in particular to resolve isotopic patterns, localise S-containing metabolites, and avoid identification errors when analytes have common nominal mass peaks in their spectrum. We provide a practical example using leaves of different Arabidopsis ecotypes and show how exact mass GC-MS analysis can be applied to plant samples and identify metabolic profiles.

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Variations in GC–MS Response Between Analytes and Deuterated Analogs

Cited by 11 publications

References 35 publications

Magic of Alpha: The Chemistry of a Remarkable Bidentate Phosphine, 1,2-Bis(di-tert-butylphosphinomethyl)benzene

Magic of Alpha: The Chemistry of a Remarkable Bidentate Phosphine, 1,2-Bis(di-tert-butylphosphinomethyl)benzene

Determining the isotopic abundance of a labeled compound by mass spectrometry and how correcting for natural abundance distribution using analogous data from the unlabeled compound leads to a systematic error

Exact mass GC-MS analysis: protocol, database, advantages and application to plant metabolic profiling

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