Handbook of GC/MS

Hübschmann, Hans‐Joachim

doi:10.1002/9783527612857

Cited by 28 publications

(4 citation statements)

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“…The sensitivity of the procedure was limited by the background signal of the instrument with approximately 1 pmol of analyte being differentiable from background, while a signal three times background was produced by approximately 4 pmol of analyte. While somewhat lower than that of GC/MS,11 such sensitivity should allow the detection of 1 ppb xylene or toluene in approximately 120 mL of air or, by sampling 1 L of air, the same compounds present at 0.1 ppb could be detected. Thus TD SIFT‐MS represents a feasible route for the offline determination of environmental toluene or xylene levels, as well as being a useful means to increase the sensitivity of the SIFT‐MS analysis above the current sensitivity limit of 5–10 ppb for online analysis.…”

Section: Discussionmentioning

confidence: 99%

The combined use of thermal desorption and selected ion flow tube mass spectrometry for the quantification of xylene and toluene in air

Ross

Vermeulen

2007

Rapid Comm Mass Spectrometry

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Thermal desorption (TD) is commonly employed for volatile chemical analysis, it being the method of choice for occupational health and safety monitoring. TD allows for offline capture of volatiles onto a solid sorbent followed by desorption and analysis at a later time. Although TD is routinely used in conjunction with gas chromatography (TD-GC), the assay throughput is low and requires the use of gas standards for quantification. Another technique increasingly employed for volatile chemical analysis, selected ion flow tube mass spectrometry (SIFT-MS), is capable of real-time absolute (i.e. without calibration standards) quantification of volatile chemicals present at single digit parts per billion or higher concentrations. SIFT-MS is, however, normally used for online direct analysis of gas samples rather than offline collection and analysis. The goal of this study was to determine whether a combination of TD and SIFT-MS could be used to quantify volatile compounds, specifically xylene and toluene, more rapidly than TD-GC and without the need for calibration standards. SIFT-MS was able to quantify xylene and toluene levels within 45 s of desorption. Due to the robustness of the SIFT-MS analysis in the presence of water vapour and other major components of air, the purging of tubes usually required to remove these constituents during the TD cycle was not required, therefore reducing the TD cycle time. Comparing the quantity of xylene and toluene applied to the TD tube with the absolute levels quantified by SIFT-MS subsequent to desorption suggested a recovery of over 95% of the applied compound. We conclude that the combination of TD and SIFT-MS allows more rapid and accurate quantification of xylene and toluene (compared with TD-GC) to be achieved without the need for calibration standards, features which may be advantageous in applications requiring rapid analysis and high throughput.

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Section: Discussionmentioning

confidence: 99%

The combined use of thermal desorption and selected ion flow tube mass spectrometry for the quantification of xylene and toluene in air

Ross

Vermeulen

2007

Rapid Comm Mass Spectrometry

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“…The carrier gas was nitrogen, which was injected in split mode at a rate of 1 mL/min (leak ratio: 1/70). The Kovats indices (KI) of compounds were calculated and compared to those of standard products listed in the Kovats [28], Adams [29], and Hübschmann [30], databases to determine the chemical composition of the essential oil. Each molecule was identified by comparing its retention time to genuine standards that were known to be kept in the laboratory of the authors.…”

Section: Gas Chromatography Coupled With Mass Spectrometry Analysis O...mentioning

confidence: 99%

A Study of the Synergistic Effects of Essential Oils from Origanum compactum and Origanum elongatum with Commercial Antibiotics against Highly Prioritized Multidrug-Resistant Bacteria for the World Health Organization

Drioiche,

Baammi,

Zibouh

et al. 2024

Metabolites

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The irrational use of antibiotics has favored the emergence of resistant bacteria, posing a serious threat to global health. To counteract antibiotic resistance, this research seeks to identify novel antimicrobials derived from essential oils that operate through several mechanisms. It aims to evaluate the quality and composition of essential oils from Origanum compactum and Origanum elongatum; test their antimicrobial activity against various strains; explore their synergies with commercial antibiotics; predict the efficacy, toxicity, and stability of compounds; and understand their molecular interactions through docking and dynamic simulations. The essential oils were extracted via hydrodistillation from the flowering tops of oregano in the Middle Atlas Mountains in Morocco. Gas chromatography combined with mass spectrometry (GC-MS) was used to examine their composition. Nine common antibiotics were chosen and tested alone or in combination with essential oils to discover synergistic effects against clinically important and resistant bacterial strains. A comprehensive in silico study was conducted, involving molecular docking and molecular dynamics simulations (MD). O. elongatum oil includes borneol (8.58%), p-cymene (42.56%), thymol (28.43%), and carvacrol (30.89%), whereas O. compactum oil is mostly composed of γ-terpinene (22.89%), p-cymene (15.84%), thymol (10.21%), and (E)-caryophyllene (3.63%). With O. compactum proving to be the most potent, these essential oils showed antibacterial action against both Gram-positive and Gram-negative bacteria. Certain antibiotics, including ciprofloxacin, ceftriaxone, amoxicillin, and ampicillin, have been shown to elicit synergistic effects. To fight resistant bacteria, the essential oils of O. compactum and O. elongatum, particularly those high in thymol and (E)-caryophyllene, seem promising when combined with antibiotics. These synergistic effects could result from their ability to target the same bacterial proteins or facilitate access to target sites, as suggested by molecular docking simulations. Molecular dynamics simulations validated the stability of the examined protein–ligand complexes, emphasizing the propensity of substances like thymol and (E)-caryophyllene for particular target proteins, opening the door to potentially effective new therapeutic approaches against pathogens resistant to multiple drugs.

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“…The deconvolution method was optimised to minimise overdeconvolution, (AnalyzerPro software method parameters were: minimum peak area value = 200, S/N = 3, width of peak = 0.01 and smoothing factor = 3). The extracted features were aligned using linear retention indexing (AnalyzerPro Spectral Works, UK) [25], and clustered using the VOCCluster algorithm [26] that assigned a unique identifier in the form of (ERI-m/z1-m/z2-m/z3-m/z4-m/z5) to each VOC isolated and grouped from the 245 samples; ERI indicated the linear retention index for the VOC environmental-feature and m/z1 … m/z n were the nominal masses of the compound's ion fragments in decreasing order of abundance needed to uniquely define the deconvolved VOC features within the data-cube. The resultant sorted, and grouped features were consolidated into an environmental-VOCdata matrix that contained the extracted peak areas for each of the features isolated from each room-air sample.…”

Section: Data Processingmentioning

confidence: 99%

The variability of volatile organic compounds in the indoor air of clinical environments

et al. 2021

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The development of clinical breath-analysis is confounded by the variability of background volatile organic compounds (VOCs). Reliable interpretation of clinical breath-analysis at individual, and cohort levels requires characterisation of clinical-VOC levels and exposures. Active-sampling with thermal-desorption/gas chromatography-mass spectrometry recorded and evaluated VOC concentrations in 245 samples of indoor air from three sites in a large National Health Service (NHS) provider trust in the UK over 27 months. Data deconvolution, alignment and clustering isolated 7344 features attributable to VOC and described the variability (composition and concentration) of respirable clinical VOC. 328 VOC were observed in more than 5% of the samples and 68 VOC appeared in more than 30% of samples. Common VOC were associated with exogenous and endogenous sources and 17 VOC were identified as seasonal differentiators. The presence of metabolites from the anaesthetic sevoflurane, and putative-disease biomarkers in room air, indicated that exhaled VOC were a source of background-pollution in clinical breath-testing activity. With the exception of solvents, and waxes associated with personal protective equipment (PPE), exhaled VOC concentrations above 3 µg m−3 are unlikely to arise from room air contamination, and in the absence of extensive survey-data, this level could be applied as a threshold for inclusion in studies, removing a potential environmental confounding-factor in developing breath-based diagnostics.

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Handbook of GC/MS

Cited by 28 publications

References 0 publications

The combined use of thermal desorption and selected ion flow tube mass spectrometry for the quantification of xylene and toluene in air

The combined use of thermal desorption and selected ion flow tube mass spectrometry for the quantification of xylene and toluene in air

A Study of the Synergistic Effects of Essential Oils from Origanum compactum and Origanum elongatum with Commercial Antibiotics against Highly Prioritized Multidrug-Resistant Bacteria for the World Health Organization

The variability of volatile organic compounds in the indoor air of clinical environments

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