GC-MS System Research Articles

β-Hydroxy β-Methyl Butyric Acid (HMB) and Its Potential Doping Relevance: A Pilot Study on Its Urinary Excretion Profile.

β-hydroxy β-methyl butyric acid (HMB), either as the free acid or in the form of its calcium salt, is a component of several dietary supplements marketed to enhance sports performance, due to its role in protein synthesis. In this pilot study, we investigated the urinary excretion profile of HMB, an endogenous metabolite of the essential amino acid leucine. The endogenous reference ranges of HMB, in human urine samples, were monitored by collecting samples from 20 volunteers. Data obtained were compared with those from controlled excretion studies, following the intake of a 3-g oral dose of HMB. Urine samples were analyzed through a targeted procedure employing a conventional GC-MS system operating in SIM mode. Our results show that the excreted urinary concentration of HMB significantly exceeds the range of endogenous concentrations for at least 24 h, making possible to detect its exogenous origin.

Human epicardial adipose tissue secretome alters metabolomic profile and induces endothelial-to-mesenchymal transition in human lymphatic endothelial cells

Abstract Background Cardiac lymphatic systems play an important role in maintaining myocardial fluid homeostasis during inflammation. We have recently reported the epicardial adipose tissue (EAT)-derived factor induces inflammation and fibrosis in atrial myocardium, which lead to atrial fibrillation (AF). However, the direct effect of EAT on the cardiac lymphatic endothelial cells (LECs) remains unknown. Objective To elucidate the effect of EAT on cardiac LECs, as one of the potential causes of AF. Methods Human EAT samples were collected from 18 consecutive patients with or without AF patients during cardiovascular surgery. They were categorized into the sinus rhythm (SR) group (n=9, 72.7±8.6 years) and the AF group (n=9, 73.3±7.4 years). Preadipocytes were extracted from EAT by homogenization and collagenase treatment, and cultured to confluence. After differentiation to mature adipocytes, cell culture supernatant was collected, and cultured with human LECs. Cell permeability was measured by using FITC-dextran assay. Tube forming ability was analyzed by seeding LECs on the extracellular matrix gels. Metabolomic profiling of LECs was performed by GC-MS system. Results RT-PCR analysis revealed that cell culture supernatant from mature adipocytes of AF patients significantly increased mRNA expression of mesenchymal marker, TAGLN/SM22a (p<0.01) in human LECs, whereas mRNA expression of lymphatic endothelial markers, LYVE1 (p=0.0552) and PROX1 (p=0.0231) were decreased in human LECs, compared to those from mature adipocytes of SR patients. These data suggest cell culture supernatant from mature adipocytes of AF patients highly induce endothelial-to-mesenchymal transition (EndMT) of LECs. When assessing the endothelial barrier function by using FITC-dextran, cell culture supernatant from mature adipocytes of AF patients significantly decreased cell barrier function (p<0.01) compared to those from mature adipocytes of SR patients. Furthermore, cell culture supernatant from mature adipocytes of AF patients significantly decreased the tube forming ability of LECs (p<0.01) compared to those from mature adipocytes of SR patients. To assess the metabolomic changes in human LECs by EAT-secretome, we conducted the GC/MS analysis. Cell culture supernatant from mature adipocytes of AF patients significantly decreased several amino acids including branched-chain amino acid (BCAA; valine, leucine and isoleucine), compared to those from mature adipocytes of SR patients. Conclusion Our study with human EAT and LECs demonstrated that EAT-secretome from AF patients altered metabolomic profile in LECs, and highly caused EndMT in LECs, leading to impaired barrier function and the tube forming ability. Defects of lymphangiogenesis could be a therapeutic target for atrial cardiomyopathy.

A Rapid Analysis Method for Determination of Hydrocarbon Types in Aviation Turbine Fuel by Gas Chromatography-Mass Spectrometry.

A rapid analysis method for determination of hydrocarbon types in aviation turbine fuel was investigated in this study. A kind of reversible adsorption material packed as an unsaturated trap was used to separate saturated hydrocarbons and unsaturated hydrocarbons in the GC-MS system. No manual process or organic reagent was needed during the entire analysis process. The contents of 13 kinds of hydrocarbons, including paraffins, monocycloparaffins, dicycloparaffins, tricycloparaffins, monoolefins, cycloolefins, alkylbenzenes, CnH2n-8 aromatics, CnH2n-10 aromatics, naphthalenes, CnH2n-14 aromatics, CnH2n-16 aromatics, and CnH2n-18 aromatics were calculated by the characteristic mass fragments detected by MS with the modified matrices of ASTM D2425. The overall analysis time was less than 10 min. The precision of this test method has been conducted with 8 laboratories attended and 16 samples analyzed. The performance of this new method was demonstrated by comparing the results tested by ASTM D1319, ASTM D2425, and ASTM D6379. This rapid analysis method can provide hydrocarbon compositions of aviation turbine fuels or other liquid hydrocarbon samples within the same distillation range.

Validation of a rapid GC–MS method for forensic seized drug screening applications

With the lack of standardized validation protocols across the forensic chemistry community, validation of instrumentation can be a challenging and time-consuming task. However, this process is crucial to understanding the associated capabilities and limitations, especially for nascent technologies. Rapid GC–MS is one such emerging analytical technique being increasingly implemented in forensic laboratories due to its fast and informative screening capabilities. However, a full validation for forensic samples has yet to be published since its debut. This work presents the results of a comprehensive validation of a rapid GC–MS system for seized drug screening through the assessment of nine components: selectivity, matrix effects, precision, accuracy, range, carryover/contamination, robustness, ruggedness, and stability. Single- and/or multi-compound test solutions of commonly encountered seized drug compounds were used to assess method and system performance. Results met the designated acceptance criteria for a majority of components. For example, retention time and mass spectral search score % RSDs were ≤10 % for precision and robustness studies. Limitations were identified for components that did not meet the acceptance criteria (e.g., inability to differentiate some isomers). The study design is part of a larger validation package developed for rapid GC–MS that includes a validation plan and automated workbook. The template, available for adoption by laboratories, ultimately aims to reduce the barrier of implementation for rapid GC–MS technology.

Chemical Composition, Antifungal, Antioxidant, and Hemolytic Activities of Moroccan Thymus capitatus Essential Oil.

This study aimed to define the chemical composition of Moroccan Thymus capitatus essential oil, and to investigate its in vitro antioxidant and antifungal activities against human pathogenic fungi. Chemical analysis using GC-FID and GC-MS system revealed 28 constituents, representing 99 % of total compounds. Oxygenated monoterpenes represented the highest proportion (79.79 %), among which carvacrol (75.73 %) was the predominant compound, followed by linalol (2.26 %). Monoterpene hydrocarbons represented the second major fraction (16.29 %): within them, the predominant constituents were γ-terpinene (5,55 %), ρ-cymene (5,50 %), and β-caryophyllene (2.73 %). Antioxidant activity was performed by DPPH scavenging, β-carotene bleaching inhibition, and ferric reducing power. T. capitatus revealed pronounced DPPH radical scavenging activity (IC50=110.53 μg mL-1), strong ferric reducing ability (EC50=644.4 μg mL-1), and a remarkable degree of protection against lipid peroxidation during β-carotene bleaching inhibition (IC50=251.76 μg mL-1). Antifungal activity was carried out against Candida, Aspergillus, and Rhizopus species by microdilution method. T. capitatus exhibited potent anticandidal activity (MIC=125-500 μg mL-1) and strong inhibition against filamentous fungi (MIC=250-500 μg mL-1). Its hemolytic activity against human erythrocytes had a low toxic effect at concentrations lower than 1250 μg mL-1. The useful antioxidant properties and broad antifungal effect of T. capitatus EO confirm its considerable potential for the food industry and for phytopharmaceutical production.

Spray-assisted drop formation liquid-phase microextraction for the determination of sertraline in environmental water samples with matrix-matching calibration in GC–MS

Sertraline is used as an antidepressant drug for the treatment of psychiatric disorders, including anxiety and depression. In the current study, a simple and effective method was developed for the sensitive monitoring of sertraline in water samples using a GC–MS system. The spray-assisted droplet formation liquid-phase microextraction (SADF-LPME) method was used as a sample preparation method for the enrichment of analytes. Accordingly, dichloromethane was used as an extraction solvent and easily dispersed into a sample/standard solution using a lab-made modified spray device without using a dispersing solvent. The significant factors affecting the SADF-LPME efficiency, including sample pH, mixing conditions, extraction solvent type, and spray cycle, were univariately optimized to ascertain the extraction performance and applicability of the system. Under the optimized conditions, the plotted calibration curve of the method was linear in the range of 100.2–2011.7 µg/kg (mass-based standard preparation) with a good correlation coefficient (R2) of 0.9997. The detection and quantification limits of method were found to be 37.5 and 125 µg/kg, respectively. Validation of the method was successfully carried out using different tap water samples and applying a matrix-matching calibration strategy. The acceptable percent recoveries were recorded between 77.3 and 133.7%, with high repeatability. The recommended method is an alternative and fast extraction method with several advantages, including a simple experimental process, good dispersibility, and fast and superior extraction performance. It can be readily applicable to the monitoring and quantification of sertraline in tap water samples with good precision and accuracy.

Chemotaxonomic and anatomic wood species identification in bleached pulp: blind test and method validation

Abstract This paper presents a comparative analysis of the blind test outcomes of two independent methods for the identification of tropical wood species in pulp and paper products. Both, the established anatomical and the relatively new chemotaxonomic method support the European Deforestation Regulation 2023/1115 (EUDR), which aims to ensure that only legally harvested timber that has not contributed to deforestation is traded in the EU. The blind test involved 570 decisions on 15 test sheets of 37 self-manufactured mixed tropical hardwood pulps and an industrial beech pulp, used as a matrix. Both detection techniques demonstrated robust performance with over 80 % hit rates. The results show that the synergies and combination of the strengths of both methods can be utilized and lead to even better combined performance. In order to establish the chemotaxonomic identification method as a complement to the conventional anatomy-based method, statistical analyses were performed to assess its intermediate precision between three different GC-MS systems. In most cases, the method gave consistent results independent of the instrument used.

Exploring Pottery Function and Cooking Practices in Bronze Age Sicily: The Results of High-resolution GC-MS of Organic Residues

ABSTRACT Despite the extended application of GC-MS for detecting organic residues from archaeological ceramics, the potential of gas chromatography – high-resolution and accuracy mass spectrometry (GC-HRAMS) has not yet been fully explored. This study conducted lipid residue analysis (using an Exactive Orbitrap GC-MS system) of dolia and jars from two Early and Middle Bronze Age (2200-1450 BC) archaeological sites in south-eastern Sicily, comparing chromatograms obtained by both GC-HRAMS and GC coupled to quadrupole, low-resolution MS (GC-LRMS). The archaeological question aimed at verifying the use of the selected vessels for cooking purposes and exploring hypotheses concerning their employment in different cooking methods (boiling or roasting) based on the analysis of morphological features and burning traces on the surfaces. The results showed clear advantages of using GC-HRAMS in targeted and untargeted approaches.

In vitro anticancer, antioxidant, cytotoxic activity and phytochemical characterization of Inula viscosa L. essential oil against colorectal cancer cell line HCT-116

Human colorectal cancer cell line (HCT116) cells are adherent epithelial cells derived from the human colorectal carcinoma cell line commonly used to study inflammatory responses in colonic epithelial cells. This study aimed to evaluate the protective effects of Inula viscosa essential oil (IVEO), an effective antioxidant compound with a radical scavenging activity in vitro using HCT-116 cells. The chemical composition of hydrodistilled IVEO was analyzed by GC-FID and GC-MS systems. The major compounds of essential oil were borneol acetate (51.54%) and borneol (21.17%). The cytotoxicity was determined using the colorimetric MTT assay for 24 h, and 48 h. Malondialdehyde (MDA) level, some enzymes activities including catalase (CAT) and superoxide dismutase (SOD) were measured in the HCT 116 cells both with and without IVEO treatment. In this study, there was a significant decrease in activities of cellular SOD and CAT, increased in the MDA levels in the cells treated with IVEO. These result indicate that IVEO can serve as an agent with strong potential to be utilized for the development of colorectal cancer chemoprevention. However, further molecular investi-gation is required to understand the molecular bearings of IVEO.

Walnut Seed Coat (Juglans regia L.), a Plant Effective in Human Health: Antioxidant Activity and in Rats Nephroprotective Effect

In the study, the seed coat (WSC) of Posof (Ardahan/Türkiye) walnuts was extracted to determine their phytochemical components and antioxidant capacities. The effects of bioactive components in the ethanol extract of WSC (E-WSC) on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors were investigated. Additionally, antioxidant enzyme activity parameters were measured in the kidney tissues of Triton WR-1339-induced hyperlipidemic rats. Bioactive compounds in WSC were identified by GC-MS system. The antioxidant properties of WSC were measured using Fe+3, Cu+2 and Fe+3-2,4,6-tripyridyl-s-triazine (TPTZ) reducing agent, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'- azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) scavenging activities. In this analysis, using 30 male Wistar rats (300 ± 30 g) randomly divided into five groups were treated as follows; K1: Healthy control group, K2: E-WSC (150 mg) o.d., K3: E-WSC (300 mg) o.d., K4: Hyperlipidemic group i.p., K5: Hyperlipidemic group i.p. + E-WSC (300 mg) o.d. Superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) analyzes were performed in kidney tissues. Based on these results, it was clearly determined that E-WSC has significant antioxidant activity due to its bioactive components, has an inhibitory effect on AChE and BChE enzymes, and has a protective effect against oxidative stress by improving hyperlipidemia-related kidney damage.

Revisiting gas-chromatography/mass-spectrometry molar response factors for quantitative analysis (FID or TIC) of glycosidic linkages in polysaccharides produced by oral bacterial biofilms

Methylation analysis was performed on methylated alditol acetate standards and Streptococcus mutans extracellular polymeric substances (EPS) produced from wild-type and Gtf knockout strains (∆GtfB, ∆GtfB, and ∆GtfD). The methylated alditol acetate standards were representative of glycosidic linkages found in S. mutans EPS and were used to calibrate the GC–MS system for an FID detector and MS (TIC) and produce molar response factor, a necessary step in quantitative analysis. FID response factors were consistent with literature values (Sweet et al., 1975) and found to be the superior option for quantitative results, although the TIC response factors now give researchers without access to an FID detector a needed option for molar response factor correction. The GC–MS analysis is then used to deliver the ratio of the linkage types within a biofilm.

Association of the short-chain fatty acid levels and dietary quality with type 2 diabetes: a case-control study based on Henan Rural Cohort.

Evidence of the relationship between fecal short-chain fatty acids (SCFA) levels, dietary quality and type 2 diabetes mellitus (T2DM) in rural populations is limited. Here, we aimed to investigate the association between fecal SCFA levels and T2DM and the combined effects of dietar quality on T2DM in rural China. In total, 100 adults were included in the case-control study. Dietary quality was assessed by the Alternate Healthy Eating Index 2010 (AHEI-2010), and SCFA levels were analysed using the GC-MS system. Generalised linear regression was conducted to calculate the OR and 95 % CI to evaluate the effect of SCFA level and dietary quality on the risk of T2DM. Finally, an interaction was used to study the combined effect of SCFA levels and AHEI-2010 scores on T2DM. T2DM participants had lower levels of acetic and butyric acid. Generalised linear regression analysis revealed that the OR (95 % CI) of the highest acetic and butyric acid levels were 0·099 (0·022, 0·441) and 0·210 (0·057, 0·774), respectively, compared with the subjects with the lowest tertile of level. We also observed a significantly lower risk of T2DM with acetic acid levels > 1330·106 μg/g or butyric acid levels > 585·031 μg/g. Moreover, the risks of higher acetic and butyric acid levels of T2DM were 0·007 (95 % CI: 0·001, 0·148), 0·005 (95 % CI: 0·001, 0·120) compared with participants with lower AHEI-2010 scores (all P < 0·05). Acetate and butyrate levels may be important modifiable beneficial factors affecting T2DM in rural China. Improving dietary quality for body metabolism balance should be encouraged to promote good health.

Phytochemical characterisation and toxicity effect of Tithonia diversifolia (Hemls.) A. Gray leaf extract on fall army worm Spodoptera frugiperda (JE Smith) larvae.

To mitigate the losses due to fall armyworm (FAW) infestation in maize, chemical pesticides had been the first choice and widely used as an emergency response. However, it comes with attendant health effect. This necessitates the development of plant based effective and safer pesticides. This research investigate response of fall armyworm larvae when they are exposed to crude and partially purified Tithonia diversifolia leaf extract. Chemical constituent of the extract was identified using NIST08.LIB library spectra provided by the software on a GC-MS system and FTIR analysis was done using KBr pellet technique with a resolution and scanning speed of 4 cm-1 and 2 mm/s. Dose dependent toxicity assay of T.diversifolia extracts on FAW at different growth stages under controlled environment in laboratory, followed by its effect under phytotron were examined against control and azadirachtin from neem. The GC-MS of the butanol eluent revealed 20 compounds out of which the major ones being beta-d-glucopyranoside, methyl (15.225 %) palmitic acid, TMS derivative (10.98 %) and hexadecanoic acid, 2-[(trimethylsily)oxy]-, methyl ester (8.75 %). The FT-IR spectroscopic analysis of the butanol eluent of T.diversifolia leaf extract revealed the presence of alcohols, phenols, aldehydes, ketones, alkanes and primary amines. The butanol eluent and crude extract caused 96 % mortality at neonate and first instar FAW larvae. The toxic and repellant effects revealed by diet bioassay and phytotron experiment respectively suggest that butanol eluent of T.diversifolia leaf extract could be a good and effective target for biopesticide production against FAW.

Implementation of simple and effective fine droplet formation-based spray-assisted liquid phase microextraction for the simultaneous determination of twenty-nine endocrine disruptor compounds and pesticides in rock, soil, water, moss, and feces samples from antarctica using gas chromatography-mass spectrometry

This study established the simultaneous determination of the selected endocrine-disrupting compounds (EDCs) and pesticides in rock, soil, water, moss, and feces samples collected from the Antarctic region. The spray-assisted droplet formation-based liquid phase microextraction (SADF-LPME) coupled to GC–MS system was developed and validated for the screening and monitoring of 29 selected EDCs and pesticides. Binary solvent system, 1:1 (v/v) dichlormethane: 1,2-dichloroethane mixture was employed as an extraction solvent and sprayed onto sample or standard solutions using a straightforward and practical spray apparatus. The factors affecting the extraction process such as extraction solvent type and ratio, extraction solvent volume (spray repetition), vortexing period, and sample pH were properly optimized. Analytical figures of the merit of the method were recorded under the optimal extraction/chromatographic conditions. The LOD, LOQ, and enhancement factor were in the range of 1.0 to 6.6 ng/g, 3.2 to 22.1 ng/g, and 3.7 to 158.9, respectively. The method demonstrated a good linear working range for all the selected analytes with proper coefficients of determination. The usability and reliability of the microextraction strategy was confirmed using seawater, moss, and soil samples, and the %recoveries were within an acceptable range (> 70%) for all examined samples. The environmental samples collected from the Horseshoe and Faure Islands of the Antarctica region were analyzed to assess the potential pollution of EDCs and pesticides. This method has the potential to be employed for the analysis of EDCs in routine analytical laboratories and for controlling and screening the organic pollutant content of different environmental samples.

Essential oil analysis and antibacterial activity of Salvia aucheri subsp. canascens and S. heldreichiana

ABSTRACT Salvia species are cultivated for their aromatic characteristics and are used as flavourings, food condiments, cosmetics. In this study, chemical constituents of the essential oil of Salvia aucheri subsp. canascens and S. heldreichiana were determined by GC-FID and GC-MS systems. α-Pinene (9.5, 13.1%), 1,8-cineole (21.2, 9.1%), β-caryophyllene (5.7, 9.0%) and borneol (6.0, 6.4%) were determined as main components for S. aucheri subsp. canascens and S. heldreichiana, respectively. In addition, major compounds were found as camphor (19.1%), camphene (7.3%) and β-pinene (4.1%) for S. aucheri subsp. canascens essential oils. Sabinene (5.4%), caryophyllene oxide (5.3%) and geranyl acetate (2.9%) were found as major compounds for S. heldreichiana essential oil. To evaluate antimicrobial activity of the essential oil, broth microdilution method was used against Staphylococcus aureus ATCC 6538, Escherichia coli NRRL B-3008, Pseudomonas aeruginosa ATCC B888, Salmonella typhimurium ATCC 13,311 bacteria. The results were found to be promising in terms of antimicrobial efficacy.

The Characterization of Volatile Compounds of Lupin Türkiye Genotype HS-SPME/GC-MS Method

The aim of this study is to reveal the volatile and semi-volatile constituent of the local Lupinus albus L. genotype grown in Türkiye by using the HS-SPME technique. Local lupin is a legume plant with great potential due to its high seed yield and protein and oil content in the seeds. Powdered seeds of local lupin genotypes were analysed and compared with respect to types and contents of volatile semi-volatile compounds contents using four different SPME fiber with GC-MS system in W9N11, SWGDR4G4 and SWGDR4G5 libraries. Fiber with 50/30 µm DVB/CAR/PDMS identified 54 compounds, 65 µm PDMS/DVB fiber 97 compounds, 85 µm Carboxen/PDMS fiber 28 compounds, and 85 µm polyacrylate 12 compounds. As a result, 65 µm PDMS/DVB fiber is the most preferable in terms of compound identification, with 97 compound. In terms of content, Benzene, Methyl(1-Methylethyl) (39.92%), Gamma-Terpinene (12.26%), Cis-Ocimene (5.93%), 1,3,6-Octatriene,3,7-Dimethyl-(% 5.51), Beta-Myrcene (4.70%), Alpha-Pinene (4.39%), Alpha.-Thujene (4.21%), Alpha Terpinene (2.55%), Camphene (2.23%), 1,6-Octadien-3-Ol,3,7-Dimethyl (2.10%) were mostly detected in the analysis with 50/30 µm DVB/CAR/PDMS fiber. With the other fiber 65 µm PDMS/DVB; phospine oxide, triphenyl- (15.49 %), pulegone (5.03 %), L-linalool (3.85 %), cyclopentasiloxane, decamethyl (3.54 %), cyclohexasiloxane, dodecamethyl (3.13 %), cyclotrisiloxane, hexamethyl (2.32 %), oxime-,methoxy-phenyl (2.08 %), 1-pentanamine,N-pentyl (1.60 %), 3,5-octadıen-2-one (1.55 %), I-menthone (1.50 %). Fiber 85 µm Carboxen/PDMS; the most four components in the content are; Benzene, 2, 4-diisocyanato-1-methyl (54.27 %), Pyrrole-3-carbonitrile, 5-formyl-2, 4 (18.41 %), 1-Butanol, 4-(1-methylethoxy) (14.67 %), pyridine,4-(1-pyrrolidinyl)- (8.13 %). With 85 µm polyacrylate fibre the most found component is 1, 2-Benzenedicarboxylic acid, diethyl ester (98.90 %). In conclusion, as far as we know this study is the first study about the volatile content of local lupin genotype of Türkiye.

Isotopic Labeling of Carbonate Solvents to Understand Gas Generation in Li-Ion Batteries and Gas Reduction by Fluorinated Organosilanes

Battery aging processes from cycling or storage at high temperatures, high voltages, and long times lead to significant degradation of the lithium-ion electrolyte, including decomposition to gaseous species. Gassing in battery pouch cells causes swelling, negatively impacting cell safety and performance. Development of electrolyte formulations that increase stability and reduce gassing is critical for next-generation battery applications and requires a greater understanding of the mechanisms of gas generation and reduction.Fluorinated organosilicon (OS) materials have been developed by Silatronix® to improve high temperature performance with significantly reduced gassing in high Ni battery systems.1 Utilization of a calibrated GC-TCD system allows the specific gas species to be identified and quantified but did not provide information on the mechanisms responsible for producing each species. To provide that information, studies using isotopically labeled carbonate solvents were conducted to identify the source for each gas species using a calibrated GC-MS system.2,3 Beyond identifying the gas species that evolve from particular carbonate solvents, these studies showed that the fluorinated organosilicon (OS) compounds reduce gassing (50-80% reduction depending on the specific OS formulation) by addressing all observed sources of gas during high temperature storage.2,3 The use of isotopically labeled carbonate solvents is extended within this study to provide insight into the origin of gas products and the nature of gas reduction by various OS materials under diverse aging conditions, including high temperature and fast charge cycling, as well as high temperature storage. This investigation includes multiple 13C-labeled electrolyte components including diethyl carbonate (DEC) and dimethyl carbonate (DMC) in addition to ethylene carbonate (EC). Carbonate-only electrolytes are compared to electrolytes containing OS compounds to gain insight into gas reduction mechanisms. Where possible, comparisons are made between different OS structures and popular commercial additives.Overall, this study builds on previous work to detail the origins of gassing from three common commercial carbonate solvents when combined in a complex electrolyte formulation under multiple test conditions and demonstrates that OS materials are highly effective gas-reducing components.

A Compact Monitor for Ethylene and Other Plant-Produced Volatile Organic Compounds for NASA Space Missions.

In this work, we discuss the development of a compact analytical instrument for monitoring ethylene in compact greenhouses utilized by NASA to grow fresh vegetables in space. Traditionally, ethylene measurements are conducted by GC-MS systems. However, in space, they are not applicable due to their bulky size, heavy weight, special carrier gas requirement and high maintenance. Our group developed a compact and robust battery-powered ethylene monitor based on the principles of analytical gas chromatography. The device utilizes purified ambient air as a carrier gas and a metal oxide sensor as a GC detector. Implementation of a CarboWax 20 M packed column from Restek together with a Tenax TA pre-concentrator allowed us to achieve a 20 ppb limit of detection for ethylene. Full automation of measurements and reporting of concentrations was accomplished via the implementation of a Raspberry Pi 4 computer and a 7″ 720P LED capacitive touchscreen utilized for data output. Based on a feasibility study, a fully automated, industrial-grade ethylene monitoring and removal system for greenhouses was developed.

Determination of cholesterol content in foods and functional foods by gas chromatography mass spectrometry GC-MS

Cholesterol is a soft, pale yellow steroid fat that exists in the body's cell membranes and is transported in the plasma of most animals. This compound plays an important role in the physiology of the human body. However, excess cholesterol in the diet is also one of the leading causes of cardiovascular diseases. Therefore, the quantification of cholesterol in foods and functional foods is essential so that consumers can choose a diet containing the right amount of cholesterol. This study used gas chromatography-mass spectrometry to quantify cholesterol, with ISQ 7000 GC-MS system, TraceGOLD TG-5MS chromatographic column, and electron impact (EI) ionization mode. The validity of the method was confirmed according to the guidelines of the Association of Official Analytical Collaborations (AOAC). The results showed that the method has good specificity, the linearity range from 5 to 100 &amp;mu;g/mL in working solution, the detection limit of 1.5 to 15 mg/kg, the quantification limit of 5.0 to 50 mg/kg, depending on the matrix; the method's recovery were from 92.6 to 108.4% and the precision has relative standard deviations of 1.18 - 2.84%, meeting the requirements of AOAC. The method was used to analyze samples of dairy foods and functional foods randomly purchased in the market.

Polychlorinated biphenyls (PCBs) and polychlorodibenzo-p-dioxins (PCDDs) determination in disposable baby diapers with the application of natural deep eutectic solvent

In this work a new method involving solvent extraction of porous membrane-packed solid samples (SE-PMSS) coupled to gas chromatography-mass spectrometry (GC–MS) has been developed for the determination of six polychlorinated biphenyls (PCBs) and five polychlorodibenzo-p-dioxines (PCDDs) in disposable baby diapers. In that aim, a terpenoid-based natural deep eutectic solvent (NADES) composed of carvone and camphor in a 1:1 M ratio was used. The extraction process consisted on a first sealing step of the homogenized whole diaper inside a polypropylene bag. The bag was then immersed in a proper amount of NADES and agitated. After that, measurements were carried out injecting the NADES with the extracted analytes directly into the GC–MS system. Previously, a design of experiment was performed employing a Box Behnken design (BBD) to calculate the optimum variables of the extraction process. With the optimum values, the method was validated obtaining good analytical features such as low limits of detection (0.065–0.60 µg/g) and limits of quantification (0.22–2.0 µg/g). Relative recoveries ranging between 84 and 114 % and relative standard deviations under 15 % for all the analytes. Finally, the green character of this method was evaluated employing the tools complementary green analytical procedure index (ComplexGAPI) and analytical greenness metric for sample preparation (AGREEprep).