GC Mass Spectrometer Research Articles

Assessment of the antibacterial efficacy of silver nanoparticles-based Artemisia annua against methicillin-resistant Staphylococcus aureus-infected lung tissues in albino rats

The production of alternative and effective medicines is crucial given that antibiotic resistance is currently a global health concern. Several biochemical identification tests were used to screen for Staphylococcus aureus isolates. Analysis of Artemisia annua extract was performed using a trace GC‒mass spectrometer, which revealed that the A. annua extract contains numerous compounds, such as artemisinins, palmitic acid and other vital essential compounds that have antioxidant and anti-inflammatory properties. The isolate st.8 was resistant to cefoxitin, oxacillin, and cephalosporins; furthermore, MALDI-TOF/MS Biotyper® identified it as methicillin-resistant S. aureus with confidence value 99.9% of mass spectrum compared with reference spectra. The synthesis of green silver nanoparticles based on A. annua as a reducing agent was confirmed via partial characterizations: (HR-TEM), (XRD), (SEM), (EDX) and (FTIR) analysis. The significant of antibacterial activity of the new green material (AgNPs) was achieved by determining the agar well diffusion assay. Furthermore, compared with those in the Staphylococcus-infected group, a significant decrease in hematological parameters was observed, with an increase in antioxidant biomarkers, a decrease in interstitial tissue thickening by inflammatory cells, and a weak positive immune reaction in a few cells (TNF-α and iNOS) in rats. Overall, this study is a promising step toward the development of new and effective strategies for combating MRSA infections.

Comparative Chemical Study For Species of The Eryngium genus

Five species of Eryngium L. (Apiaceae) native to Iraq-Eryngium glomeratumLam, Eryngium creticum Lam, Eryngium thyrosoideum Boiss, Eryngium billardieri Lam., and L. Eryngium campestre—are the focus of this comparative chemical taxonomy. Chemical analysis revealed that the five species within the genus could be distinguished by their unique chemical signatures thanks to applying the GC Mass Spectrometer (GC-MS) technique to their secondary metabolic components. Species shared specific molecules but had distinct chemical make-ups in others. The chemical properties of the species in the genus were used to calculate Euclidean genetic distance values; the highest value was found to be 5.1962 between E.creticum and E.billardieri, and the pair with the smallest value of Euclidean distance (3.70) was E. campestre and E. billardieri. The clustering analysis was displayed in the phylogenetic tree. The species can be classified into three broad categories along a single Euclidean axis, as indicated by chemical evidence that corroborated the result of Principal Component Analysis (4.9). (PCA). The studies also demonstrated the ability to differentiate and identify evolutionary links across species by showing the independence of species in specific isolated chemicals. Keywords: Eryngium; genus; Chemical taxonomic; Lam Eryngium, (GC-MS) technique.

Proposal of a new mechanism of ammonia on the coking inhibition of n-decane under supercritical conditions

The coking problem of hydrocarbon fuel pyrolysis is the key factor affecting the application of active cooling technology for high-speed aircraft. The purpose of this work is to investigate the coking inhibition performance and coking mechanism of using ammonia as an additive during the thermal cracking. In this study, the pyrolysis and coking characteristics of supercritical n-decane were experimentally studied using an electrically heated tube. ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer), GC–MS (Gas Chromatograph Mass Spectrometer), SEM (Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), TPO (Temperature Programmed Oxidation), and Raman spectroscopy are applied to characterize the anti-coking performance of the additives. The results show that the additive hardly affects the cracking of the fuel under high-temperature conditions, but the coke mass deposited on the inner surface of the tube is significantly reduced, and the coking inhibition rate can reach 80% at 750 °C. The addition of additives reduced the graphitization degree and oxidative activity of the coke. The maximum oxidation temperature of the coke obtained at 750 °C was reduced by 145 °C, and the ID/IG value of the Raman spectroscopy peak-fitting was 3.29. The new mechanism of the effect of additives on the formation of coking precursors and the deposition of coke on the surface of the tube wall is proposed. Ammonia can react with Ni of the inner metal tube and radicals generated by fuel cracking to form a carbonized film, achieving the effect of inhibiting metal catalytic coking. Meanwhile, the amino radicals generated by ammonia dehydrogenation can regulate the coking reaction path by forming a stable p-π conjugate structure with unsaturated radicals. Therefore, the research will contribute to a deeper comprehension of the coking inhibition mechanism and the development of more effective coking inhibitors, providing new technical support for active cooling technologies.

UHPLC-MS and GC-MS phytochemical profiling, amelioration of pain and inflammation with chloroform extract of Funaria hygrometrica Hedw. via modulation of inflammatory biomarkers.

People of Pakistan have undisturbed customs for the employment of medicinal plants for healthcare requisites. Chloroform extract of F. hygrometrica (CE FH) was examined for its ability to reduce inflammation and to produce analgesia. Carrageenan and formalin-induced paw edema model for inflammatory activity, hot-plate and tail-flick methods to assess analgesic activity were executed. Phytochemical analysis was done by UHPLC-MS and GC-mass spectrometer. The results demonstrated that in carrageenan-induced paw edema, maximum reduction in inflammation was observed at 5th hour at the dose 100mg/kg; while at doses 250 and 500mg/kg, maximum response was observed at 5th and 6th hours. Analgesic activity results indicated that maximum analgesia was observed up to 120min at 100mg/kg, while up to 90min in case of 250 and 500mg/kg doses. The formalin-induced rat paw edema showed significant (p < 0.05) anti-inflammatory activity after 5days treatment. After, testing period of 10days, the biochemical parameters such as CBC, CRP, serum enzymes like CAT, SOD, GSH and inflammatory mediators like TNF-α, IL-6, IL-4 and IL-10 were estimated. The administration of formalin resulted in an increase in the level of leucocytes, total WBC, CRP, serum enzymes and in the diameters of paw thickness, while pre-treatment with CE FH at dose levels of 100, 250 and 500mg/kg exhibited a diminution in the levels of SOD, GSH, CAT, total RBC and HB. Acute inflammatory mediators such as TNFα, IL -6 and IL-4 were reduced, and IL-10 was upregulated in the treated group as compared to the control. Many phytoconstituents, i.e., chitobiose, chlorovulone III, γ-tocotrienol, emmotin, cassine, hexacosanedioic acid, neophytadiene, fumaric acid, neophytadiene, hexadecanoic acid, phytol and stigmasterol were detected during UHPLC-MS and GC-MS analysis seems to be responsible for the said activity in correlation with the already reported data about these compounds. The results concluded that CE FH possess noteworthy anti-inflammatory and central analgesic action at different doses (100, 250 and 500mg/kg).

Morphological, phytochemical, and essential oil changes induced by different nitrogen supply forms and salinity stress in Echinacea purpurea L.

Salinity is one of the most important environmental factors that affect the plants growth and phytochemical compounds. So, this study was aimed to investigate the effect of salinity stress (15 mM, 30 mM, and 60 mM NaCl) and different NO3−/NH4+ ratios (90:10; 80:20, and 70:30) on Echinacea purpurea properties in greenhouse conditions. A wide range of morphological properties and phytochemical compounds were determined based on the standard methods. Essential oil analyses was performed by using GC-Mass spectrometer. According to the results, plant height, total biomass, and fresh root weight decreased by 49.6, 43.2, 40.5% after the application of 60 mM NaCl, compared with control plants. However, an increase in total leaf phenolic content, flavonoid content, PAL enzyme activity, super oxide, and nitric oxide anti-radical scavenging activities by 44, 37.2, 57.9, 46, and 27.2% were found in plants grown under 30 mM NaCl salt stress conditions, respectively compared with control plants. The major terpene hydrocarbons found in the E. purpurea extract were germacrene D (60.3%), myrcene (19.8%), α-pinene (13.1%), β-caryophyllene (12.3%), and 1-Pentadecene (5.1%), respectively. It can be concluded that, 30 mM NaCl and 90:10 NO3−/NH4+ ratio are effective for improving phytochemical properties of E. purpurea.

Insights into the mechanism of tar reforming using biochar as a catalyst

Biochar is an efficient catalyst for tar removal from syngas during biomass gasification. The aim of this research is to investigate the mechanism of tar reforming using biochar as a catalyst. A series of in situ steam tar reforming experiments were carried out using a two-stage fluidized-bed/fixed-bed reactor at 800 °C. Mallee wood biochar (106–250 μm) was activated in 15 vol% H2O balanced with Ar for different times (0–50 min) and then used as a catalyst for tar reforming. The on-line gas composition, light tar composition and the pore structure of biochar were analysed using mass spectrometer (MS), GC–MS and synchrotron small angle X-ray scattering (SAXS) respectively. An increased ratio of H2/CO was observed after reforming with biochar compared to reforming without biochar. The destruction of light tar compounds, especially the non-oxygen-containing compounds, was significantly enhanced when activated biochars were used. Steam activation increased the specific surface area (SSA), micro- and mesopore volumes in biochar while the values stayed almost unchanged during tar reforming. Results indicate that the micro- and mesopores in biochar promote the diffusion of both small and large tar molecules into the internal surface of biochar. However, the catalytic activity of biochar for tar reforming mainly depends on the content of O-containing functional groups in biochar. The O-containing functional groups facilitate the dissociation of tar molecules to form tar radicals, giving rise to the enhanced tar removal efficiency. Moreover, the formation of tar radicals over O-containing functional groups appears as the rate-limiting step in the process of catalytic reforming of tar over biochar catalysts.

Microbiome Reengineering by Heat Selection for Rapid Biodegradation of Trichloroethylene with Minimal Vinyl Chloride Formation

Trichloroethylene (TCE) was a widely used industrial solvent but is now regarded as a notorious groundwater contaminant. Both physicochemical and biological methods have been applied to remediate groundwater contaminated by TCE. For medium to low level of TCE contamination, bioremediation could be more cost-effective. However, bioremediation approaches suffer from slow degradation rates and accumulation of vinyl chloride (VC). In addition, bioaugmentation is often highly encouraged but may introduce foreign genes and increase the pace of microbial evolution. In this study, a microbiome reengineering strategy by heat selection is applied to solve these problems. Out of eight heat-treated mixed cultures, two showed a much-improved TCE degradation rate, more than 70 times higher than the untreated. The biodegradation half-life (t1/2) of TCE was 0.0627 d or shorter. No VC was detected by a gas chromatography equipped with flame ionization detector (GC-FID) and only a minimal amount by a GC-mass spectrometer (GC-MS). Ethene achieved a fairly good mass balance. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and next-generation sequencing (NGS) results showed that the heating process did not kill most bacteria, but Dehalococcoides were either not present or very scarce. Acetoanaerobium and Methanosarcina could be the most important species in this reductive dechlorination process. Kinetic study results showed that the maximum specific TCE degradation rate was approximately 1,271 nmole/min/mg cell protein, which are two orders of magnitude higher than that of the mixed cultures reported in literature. These results suggest that apart from biostimulation and bioaugmentation, microbiome reengineering could be a promising approach for rapid bioremediation of TCE-contaminated aquifers.

Croton gratissimus - essential oil composition and chemometric analysis of an ethnomedicinally important tree from South Africa

Croton gratissimus Burch. is widely used in traditional medicine to treat a range of conditions including malaria, hypertension, diabetes, arthritis, urinary tract infections, gonorrhoea and impotence. The young branches and leaves are pleasantly aromatic, and it is recorded that various ethnic groups in South Africa used the leaves as a perfume. The chemistry of the non-volatile constituents has been widely investigated. However, little scientific data on the volatile constituents are available. Essential oils (EOs) were obtained by hydrodistillation from the leaves and twigs (n = 62) collected at different locations in South Africa. The hydrodistilled oils were analysed with gas chromatography coupled simultaneously to a mass spectrometer (MS) and a flame ionisation detector (FID). GC–MS/FID of the EOs showed the presence of mono- and sesquiterpenes as the major class of compounds. The most abundant compounds were β-pinene (nd–13.7%), sabinene (0.2–16.7%), α-phellandrene (0.4–44.3%), Z-β-ocimene (0.2–12.5%), limonene (0.2–38.3%), p-cymene (0.1–25.2%), phytol (nd–24.9%) and oxidohimachalene (nd–54.6%). Untargeted analysis of the GC–MS data was performed using SIMCA-P + 14.0, and different methods were used to explore possible chemical variation in the data set. After principal component analysis (PCA), the hierarchical cluster analysis (HCA) revealed three major chemotypes. Loadings and contribution plots identified oxidohimachalene as the main chemical marker for chemotype 1. Chemotype 2 was dominated by α-phellandrene, α-pinene and p-cymene, while chemotype 3 was characterised by low yields of α-phellandrene and oxidohimachalene. This study revealed mostly quantitative rather than qualitative variation in the EOs constituents of C. gratissimus.

The Selective Conversion of Methyl and Ethyl Acetate to High Content Alkyl Aromatic Hydrocarbons over H-ZSM5

This research is devoted to a catalytic process using the H-ZSM5 catalyst for the conversion of methyl and ethyl acetate to hydrocarbon aromatics. These reactions are carried out in a fixed bed reactor under atmospheric pressure at 370°C. The distribution of products was measured by GC-Mass spectrometer. The variation of weight hourly space velocity (WHSV) on the conversion of these esters to aromatic hydrocarbons showed a significant effect on carbon distribution. The deactivation catalyst by time was monitored using product selectivity and conversion. The production of alkyl and poly alkyl aromatic compounds was formed under controlled conditions. The advantages of these methods are the formation of a higher concentration of octane number booster poly alkyl aromatic compounds (mono-aromatics) from esters as starting materials. Moreover, the catalyst lifetime on stream was investigated and exhibited longer catalyst lifetime for ethyl acetate conversion than methyl acetate.

Risk Assessment of Polycyclic Aromatic Hydrocarbons in Pasta Products Consumed in Nigeria

Background: The present study aimed to quantitatively determine polycyclic aromatic hydrocarbons in pastas consumed in Nigeria with the view of estimating the daily intake amount and the possible risks to consumers. Methods: Sixteen polycyclic aromatic hydrocarbons (PAHs) were determined in locally produced and imported pasta using a GC-Mass Spectrometer. Estimation of daily intake was done on generally exposed (low) and typically exposed (high) consumers. The margin of exposure was used to assess the risk to consumers. Results: The concentration of Σ 16 PAHs in Nigerian and imported brands were in the range of 9 to 800µg/kg and 2 to 7µg/kg, respectively. The benzo[a]pyrene (BaP) concentrations in 25% of Nigerian samples were above the maximum allowable level in processed cereal-based food. The concentrations of Σ8 carcinogenic PAHs in the Nigerian and imported brands ranged from 1 to 10µg/kg and 1 to 4µg/kg respectively. The Margin of Exposure (MOE) based on PAH8 for generally exposed children was less than 10,000 in 25% of Nigerian brands while it was 38% for typically exposed children. For imported brands of pastas, the MOE values were far higher than 10,000 for generally and typically exposed children and adults. Conclusions: The MOE values indicate serious concern particularly for children who are the major consumers of Nigerian pastas. This study is the first of its kind in Nigeria and can serve as a useful baseline for continuous monitoring of PAHs in the Nigerian pastas in order to ensure protection of human health in the country.

Mechanism of Decane Decomposition in a Pulsed Dielectric Barrier Discharge Reactor

Decane decomposition in Ar, N2, and O2/N2 gases was investigated using a pulsed dielectric barrier discharge reactor. The mechanism of decomposition was discussed on the basis of the products detected by gas chromatograph (GC) and GC-mass spectrometer techniques. Decane decomposition in Ar was initiated by dehydrogenation to form decane radicals, which were then dehydrogenated to yield decenes, lighter hydrocarbons. When O2 was present in the discharge space, decane radicals were oxidized to decanone, CO, and CO2. The oxidation mechanism of decane radicals to CO and CO2 was suggested due to the radical oxidation by O atoms and OH radicals. Nanoparticles were found in a size range of 5.5–160 nm. The sizes of the nanoparticles were different with the gas components due to the difference in the produced radicals in the discharge space. We proposed that the oxidation and nitridation of the decane led to the formation of the nanoparticles.

An Innovative Rapid Method for Analysis of 10 Organophosphorus Pesticide Residues in Wheat by HS-SPME-GC-FPD/MSD.

The rapid detection of pesticide residues in wheat has become a top food security priority. A solvent-free headspace solid-phase microextraction (HS-SPME) has been evaluated for rapid screening of organophosphorus pesticide (OPP) residues in wheat with high sensitivity. Individual wheat samples (1.7 g), spiked with 10 OPPs, were placed in a 4 mL sealed amber glass vial and heated at 60°C for 45 min. During this time, the OPP residues were extracted with a 50 μm/30 μm divinylbenzene (DVB)/carboxen (CAR)/plasma desorption mass spectroscopy polydimethylsiloxane (PDMS) fiber from the headspace above the sample. The fiber was then removed and injected into the GC injection port at 250°C for desorption of the extracted chemicals. The multiple residues were identified by a GC mass spectrometer detector (GC-MSD) and quantified with a GC flame photometric detector (GC-FPD). Seven spiked levels of 10 OPPs on wheat were analyzed. The GC responses for a 50 μm/30 μm DVB/CAR/PDMS fiber increased with increasing spiking levels, yielding significant (R(2) > 0.98) linear regressions. The lowest LODs of the multiple pesticide standards were evaluated under the conditions of the validation study in a range of levels from 0 (control) to 100 ng of pesticide residue per g of wheat that separated on a low-polar GC capillary column (Agilent DB-35UI). The results of the HS-SPME method were compared with the QuEChERS AOAC 2007.01 method and they showed several advantages over the latter. These included improved sensitivity, selectivity, and simplicity.

Fast gas chromatographic residue analysis in animal feed using split injection and atmospheric pressure chemical ionisation tandem mass spectrometry

Significant speed improvement for instrumental runtime would make GC–MS much more attractive for determination of pesticides and contaminants and as complementary technique to LC–MS. This was the trigger to develop a fast method (time between injections less than 10min) for the determination of pesticides and PCBs that are not (or less) amenable to LC–MS. A key factor in achieving shorter analysis time was the use of split injection (1:10) which allowed the use of a much higher initial GC oven temperature. A shorter column (15m), higher temperature ramp, and higher carrier gas flow rate (6mL/min) further contributed to analysis-time reduction. Chromatographic resolution was slightly compromised but still well fit-for-purpose. Due to the high sensitivity of the technique used (GC–APCI-triple quadrupole MS/MS), quantification and identification were still possible down to the 10μg/kg level, which was demonstrated by successful validation of the method for complex feed matrices according to EU guidelines. Other advantages of the method included a better compatibility of acetonitrile extracts (e.g. QuEChERS) with GC, and a reduced transfer of co-extractants into the GC column and mass spectrometer.

PGPR enhanced phytoremediation of petroleum contaminated soil and rhizosphere microbial community response

The aim of this study was to investigate petroleum phytoremediation enhancement by plant growth promoting bacteria (PGPR), specifically the correlation between petroleum hydrocarbon fractions and bacterial community structure affected by remediation and PGPR inocula. Aged petroleum contaminated soil was remediated by tall fescue (Testuca arundinacea L.) inoculated with two PGPR strains. Hydrocarbon degradation was measured by GC–MS (Gas-chromatography Mass-spectrometer) based on carbon fraction numbers (C8–C34). Changes in bacterial community structure were analyzed by high-throughput pyrosequencing of 16s rRNA. PGPR inoculation increased tall fescue biomass and petroleum hydrocarbons were removed in all the treatments. Maximum hydrocarbon removal, particular high molecular weight (C21–C34) aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs), was observed in tall fescue inoculated with PGPR. The relative abundance of phyla γ-proteobacteria and Bacteroidetes increased after different treatments compared with controls. Moreover, a bacterial guild mainly comprising the genera Lysobacter, Pseudoxanthomonas, Planctomyces, Nocardioides, Hydrogenophaga, Ohtaekwangia was found to be positively correlated with C21–C34 petroleum hydrocarbons fractions removal by RDA analysis, implying that petroleum degradation was unrelated to bacterial community diversity but positively correlated with specific petroleum degraders and biosurfactant producers.

Synthesis and Spectral Analysis of Mn (II), Cu (II) ,Ni (II) and Cd (II) Complexes with Mixed Ligands containing 1,10-phenanthroline and Schiff base derived of 4-aminoantipyrine

The complexes of Schiff base of 4-aminoantipyrine and 1,10-phenanthroline with metal ions Mn (II), Cu (II), Ni (II) and Cd (II) were prepared in ethanolic solution, these complexes were characterized by Infrared , electronic spectra, molar conductance, Atomic Absorption ,microanalysis elemental and magnetic moment measurements. From these studies the tetrahedral geometry structure for the prepared complexes were suggested.The prepared ligand of 4-aminoantipyrine was characterized by using Gc-mass spectrometer .

Synthesis and Spectral Analysis of Mn (II), Cu (II) ,Ni (II) and Cd (II) Complexes with Mixed Ligands containing 1,10-phenanthroline and Schiff base derived of 4-aminoantipyrine

The complexes of Schiff base of 4-aminoantipyrine and 1,10-phenanthroline with metal ions Mn (II), Cu (II), Ni (II) and Cd (II) were prepared in ethanolic solution, these complexes were characterized by Infrared , electronic spectra, molar conductance, Atomic Absorption ,microanalysis elemental and magnetic moment measurements. From these studies the tetrahedral geometry structure for the prepared complexes were suggested.The prepared ligand of 4-aminoantipyrine was characterized by using Gc-mass spectrometer .

Spirulina can increase total-body vitamin A stores of Chinese school-age children as determined by a paired isotope dilution technique.

Spirulina is an alga rich in high-quality protein and carotenoids. It is unclear whether spirulina can improve the total-body vitamin A stores of school-age children in China with a high prevalence of vitamin A malnutrition. We aimed to evaluate the efficacy of spirulina in improving the total-body vitamin A stores of school-age children in rural areas of China when they consumed spirulina in their daily meals. A total of 228 children (6-11 years) were recruited and randomly divided into three groups supplemented with 4g (containing 4·18µg β-carotene), 2g (containing 2·54µg β-carotene) or 0g spirulina 5d/week for 10 weeks, respectively. Before and after the intervention period, each child was given 0·5mg [(2)H4]retinyl acetate and [(2)H8]retinyl acetate, respectively. To assess vitamin A stores, blood samples (3ml) were collected on the third and the twenty-first day after each labelled retinyl acetate dose for a retinol enrichment analysis using a GC mass spectrometer. The concentrations of retinol and β-carotene in serum samples were also determined by using HPLC. After the 10-week intervention, serum β-carotene concentrations of children with 2 or 4g spirulina supplement increased by 0·160 and 0·389µmmol/l, respectively. Total-body vitamin A stores increased significantly, with a median increase of 0·160mmol in children taking 2g spirulina and of 0·279mmol in children taking 4g spirulina. Spirulina is a good dietary source of β-carotene, which may effectively increase the total-body vitamin A stores of Chinese school-age children.

Analysis of isopropyl para‐toluenesulphonate in palm‐based esters by gas chromatography with flame ionization detection and confirmed with mass spectrometry

A simple and rapid gas chromatography (GC) method with flame ionization detector was developed for detection of isopropyl para-toluenesulphonate (IPTS) in palm-based isopropyl palmitate (IPP) and isopropyl myristate (IPM). The method involved spiking the IPP/IPM samples with IPTS and directly injecting the spiked samples into GC without undergoing clean-up steps. The calibration curves for IPTS showed good linearity with coefficient correlation of 0.9999 for six-point calibration from 0.5 to 50μgmL(-1) and 0.9996 for six-point calibration from 0.5 to 200μgmL(-1) . IPTS recoveries from IPP were 98.6-103.5% with relative standard deviation (RSD) of 0.40-2.80%, whereas recoveries from IPM were 97.0-107.2% with RSD of 0.42-4.21%. The identity of IPTS recovered from the isopropyl esters was confirmed by a GC-mass spectrometer detector. The method was successfully applied to the analyses of IPTS in commercial samples. It was found that there were IPTS in the range of 34.8-1303.0μgg(-1) in the palm-based esters for some of the samples analysed.

Analysis of steroids in human urine by on line liquid chromatography–gas chromatography–mass spectrometry using the Through Oven Transfer Adsorption Desorption interface and a fraction collector

Anti-doping laboratories accredited by the WADA (World Anti-Doping Agency) must have available methods capable of detecting synthetic steroids at concentrations below 10ngmL−1 and, at the same time, be able to quantify endogenous steroids with accuracy. The unequivocal identification of the steroids must be carried out by GC–MS. In this manuscript we describe a new method by on-line coupled liquid chromatography–gas chromatography (LC–GC) using the Through Oven Transfer Adsorption Desorption (TOTAD) interface and mass spectrometer (MS) detector. By this means, all the analyte eluted in the LC stage are automatically transferred to the GC, avoiding the contamination associated with manipulation of the sample. A newly designed fraction collector is described for the first time. The collector permits the different fractions eluted in LC to be stored and sent individually to the GC by means of the TOTAD interface. The detection limits attained, measured in gas chromatography–mass spectrometry (GC–MS) in SCAN mode, vary between 0.5 and 3.4ngmL−1, and the method, once the sample is derivatized, is completely automatic.

Deuterium exchange rate between [formula omitted] and organic CH bonds: Implication for D enrichment in meteoritic IOM

The rate of the transfer of deuterium from D 3 + to the three types (benzylic, aliphatic and aromatic) of bonds of 2-Ethylnaphthalene (and Methylnaphthalene) has been measured in the laboratory. The D/H ratio of each bond was calculated from the mass spectrum of the different isotopomers produced in the source of the GC mass spectrometer. The relations between the D/H ratio of the different isotopomers allow to calculate the internal isotopic fractionation factors ( α i− j = (D/H) i /(D/H) j ) between the 3 bonds: α Benzylic–Aromatic = 1.99 ± 0.38 and α Aliphatic–Aromatic = 1.22 ± 0.39. Isotopic exchange rate constants are ⩾2.2 × 10 −7±0.4 s −1, determined at room temperature for 10 −3 g of 2-Ethylnaphthalene in contact with 5 × 10 12 cm −3 of D 3 + . These results are compatible with those measured in the insoluble organic matter (IOM) isolated from the Orgueil meteorite ( Remusat et al., 2006), i.e., α Benzylic–Aromatic = 1.96 ± 0.05 and α Aliphatic–Aromatic = 1.35 ± 0.05. Using the calculated dust and H 2D + densities from the models of deuterium chemistry in protostellar disks, the duration needed to enrich the IOM up to its measured D/H ratio is ⩽10 4±1 s. These laboratory results are in agreement with a late deuteration of the insoluble organic matter taking place in the solar T-Tauri disk by interaction of the organic dust with H 2D +.