Gas Chromatograph Coupled With A Mass Spectrometer Research Articles

Chemical composition of the headspace volatiles of intact cowpea pods and cowpea pods infested by Riptortus dentipes and Nezara viridula pests

Volatile organic compounds are released by plants in defense against herbivory feeding by insect pests. Pod-sucking bugs can cause 30–70 % yield losses in cowpea (Vigna unguiculata) which serves as a major source of rich proteins and vitamins for humans and animals, as well as a source of income for farmers. The purpose of this study was to determine the chemical composition of the headspace volatiles of intact cowpea pods (Vigna unguiculata) variety (Padituya), and when it is infested by two pod-sucking bugs Riptortus dentipes and Nezara viridula. Headspace volatile collection was employed to collect volatile organic compounds from the intact cowpea pods, cowpea pods infested with Riptortus dentipes, and cowpea pods infested with Nezara viridula. Entrainment was done for 96 h in each case. The entrained volatiles were analyzed by gas chromatograph coupled with a mass spectrometer (GC-MS). Analysis of GC-MS data led to the identification of 1-octen-3-ol, 3-octanol, 2-nonanone, oleic acid, octadecanoic acid and dodecanoic acid as the volatiles released by the cowpea pod without insect attack. Cowpea pods attacked by Riptortus dentipes released hexanoic acid, 3-hexenoic acid (E), hexanoic acid, 2-hexenyl hexanoate (E), 2-tridecanone, 1-(4-ethylphenyl)-ethanone and eicosanoic acid. Upon infestation with Nezara viridula, the pods released 2-pentanone, 4-hydroxy-4-methyl-, 3-ethylbenzaldehyde, 1-(4-ethylphenyl)-ethanone and 2-decenyl acetate (E). With the exception of 1-(4-ethylphenyl)-ethanone, different volatile organic compounds were released by the cowpea plant against the two pests upon infestation. These compounds could be synthesized and used in integrated pest management of these pests to reduce losses in yield of cowpea production.

Enfluran Metoda oznaczania w powietrzu na stanowiskach pracy z zastosowaniem chromatografii gazowej1

Enflurane is an inhaled general anaesthetic and is a positional isomer of another anaesthetic, namely isoflurane. At room temperature, it is a colourless, transparent liquid with a faint, sweet odour. In occupational exposure, enflurane is often used in a mixture with other inhalation anaesthetics, so symptoms are difficult to attribute to the effects of any one substance. Symptoms such as eye and skin irritation, central nervous system depression, cardiovascular disorders, and liver and kidney damage have been reported in workers exposed to anaesthetic mixtures. The aim of this research work was to develop and validate a method for the determination of enflurane in air at workplaces. This enflurane determination method is based on the adsorption of substance vapours on the ‘Petroleum Charcoal’ activated carbon, extraction with toluene and chromatographic analysis of the resulting solution. The tests used a gas chromatograph coupled with a mass spectrometer (GC-MS) fitted with a capillary polar column ZB-WAXplus (60 m length, 0.25 mm diameter and 0.5 µm stationary phase film thickness). The SIM mass spectrometer readings as a function of enflurane concentration within the tested concentration range (10.0–400 µg/ml) are linear. The analytical method developed enables the determination of enflurane in air at workplaces in the presence of other inhalation anaesthetics. The method is precise and accurate and it meets the requirements of PN-EN 482 for the determination of chemicals. The method developed for the determination of enflurane in air at workplaces has been recorded as an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering studies.

A GC-MC analysis of chemical compounds and identification of the antibacterial characteristics of the essential oil of two species exclusive to Iranian habitats: New chemotypes.

BackgroundThe diversity found in the chemical compounds of a single species in different regions results in different biologic characteristics which can be considered as a strong source for identifying new chemotypes. Hymenocrater incanus Bunge and Dracocephalum kotschyi Boiss. are exclusive species of the Lamiaceae family which grow in the western and central habitats of Iran. This study was designed and carried out to determine the yield, identify the chemical compounds, and evaluate the antimicrobial characteristics of the essential oil (EO) of these two species in Iran for the first time.MethodsThe flowering twigs of the species D. kotschyi and H. incanus were collected from the villages of Totmach and Kamu in Isfahan province respectively, in May 2019. The EO of these plants was extracted and separated using the water distillation method, utilizing the Clevenger device. The EO compounds were analyzed using a gas chromatograph coupled with a mass spectrometer (GC-MS). The evaluation of antimicrobial characteristics was carried out by determining the growth inhibition zone implementing the Agar method, the minimum inhibition concentration (MIC), and the minimum bactericidal/fungicidal concentration (MFC/MBC) utilizing liquid dilution culture.ResultsThe results indicated that the highest yield belonged to the EO of D. kotschyi at %2.6 (w/w). In this EO there were citral (%25.44), neral (%20.87), α-pinene (%14.48), trans-geranic acid methyl ester (%9.74), and D-limonene (%6.87). Moreover, H. incanus had the dominant compounds (-)-Spathulenol (%12.61), caryophyllene (%10.00), linolenic acid (%8.54), 1,8-cineole (%5.95), palmitic acid (%5.35), and α-cadinol (%5.17). The largest diameter of growth inhibition zone belonged to the H. incanus EO against the Gram-positive bacteria S. pyogenes (~17.67mm). The strongest inhibition activities in the form of growth inhibition diameter exhibited by the D. kotschyi EO were against the Gram-negative bacteria S. paratyphi-A serotype (~ 12 mm), K. pneumoniae, and Sh. dysenteriae (~ 11 mm) which was significant compared to the Gram-positive rifampin (~ 8 mm).ConclusionsIt can be seen that these species are new chemotypes with special and novel chemical compounds which can potentially be used to manufacture natural antibiotics against some bacterial strains.

Determination of 1-chloro-2,3-epoxypropane in order to assess the working environment

1-Chloro-2,3-epoxypropane, known as epichlorohydrin (ECH), is a colorless liquid used in the production of epoxy resins, synthetic glycerine, elastomers, glycidyl ethers, surfactants, polyamide-epichlorohydrin resins and others. Epichlorohydrin may cause cancer. The aim of this study was to develop a new method for determining concentrations of ECH in workplace air in the range of 1/10-2 values of the maximum admissible concentration (MAC). The paper presents a method for the determination of ECH in workplace air using a gas chromatograph coupled with a mass spectrometer (GC-MS). The developed method is based on the adsorption of ECH on an activated charcoal, extraction with acetone, and a chromatographic analysis of the resulting solution. The method developed makes it possible to determine ECH in the concentration range of 0.1-2 mg/m3, i.e., 1/10-2 values of MAC established in Poland. The limit of detection (LOD) is 0.24 μg/m3 and the limit of quantification (LOQ) is 0.71 μg/m3. The method is characterized by good precision and accuracy; it meets the requirements of the European standard PN-EN 482, and can be used by occupational hygiene laboratories to measure concentrations of ECH in workplace air, with a view to assessing workers' exposure to this substance. Med Pr. 2020;71(6):715-23.

Determination of Propane-1,3-sultone in Workplace Air for Occupational Exposure Assessment.

Propane-1,3-sultone (PS) is an alkylating substance used in the production of polymers, fungicides, insecticides, dyes, and detergents. It is absorbed into the human body by inhalation, digestion, and through the skin; it is also a possible carcinogen. Occupational exposure to this substance may occur on industrial or laboratory contact. In Poland, the maximum allowable concentration (MAC) for PS in workplace air is 7 µg/m3. The paper presents a method for determination of PS in workplace air using a gas chromatograph coupled with a mass spectrometer (GC-MS). Air containing PS is passed through a glass tube containing a glass fiber filter and two layers of silica gel. The substance is washed with acetonitrile and the solution obtained analysed using GC-MS. The measuring range for an air sample of 360 L is 0.7 ÷ 14 µg/m3. The limit of detection (LOD) is 13 ng/m3, limit of quantification (LOQ) is 40 ng/m3.

Experimental investigation of rice straw oxidative pyrolysis process in a hot-rod reactor

In order to improve the utilization of rice straw resources, oxidative pyrolysis of rice straw was investigated in this work. The effects of temperature and oxygen concentration on rice straw oxidative pyrolysis were taken into consideration. Results show that more permanent gases and water were produced under oxidative atmospheres, while the yield of char and tar decreased. The main gaseous products were CO and CO2 due to the heterogenous oxidation of rice straw/char or secondary reaction of nascent volatiles. Gas chromatograph coupled with a mass spectrometer (GC/MS) results show that the oxidative pyrolysis promoted the conversion of primary tar to generate secondary and tertiary tar via in-situ exothermic reaction and active radical attack. Pore structure analysis results of bio-char samples show that oxidative treatment benefited the formation of micro pores and inhibited bio-char thermal annealing at high temperature. In general, the oxidative treatment promoted the pyrolysis process and benefited the char modification via in-situ oxidation and formation surface active structure and porosity.

Yield and Composition of the Essential oil of Tetradenia riparia (Hochst) Codd (Lamiaceae) Cultivated Under Different Shading Levels

ABSTRACT: Light has direct influence on growth and development by altering the morphophysiology of the plant and the content and composition of secondary metabolites. The present study aimed to evaluate the yield and composition of the essential oil of Tetradenia riparia cultivated under different shading levels. Plants were propagated by cuttings and cultivated either under full sunlight and in environment completely covered by black polyethylene sheeting to obtain shading levels of 30%, 50%, and 80%. Plants were grown under experimental conditions for 150 days. The essential oil was extracted from fresh leaves in triplicate for each treatment through steam distillation with a modified Clevenger apparatus. The components of the essential oil were identified using a gas chromatograph coupled with a mass spectrometer (GC/MS), and compared to retention indices and authentic mass. The largest yields of essential oil came from plants cultivated under 30% and 50% shading, followed by plants cultiveted under full sunlight and under 80% shading. The main component found was the sesquiterpene hydrocarbon 14-hydroxy-9-epi-(E)-caryophyllene. Some components, such as verbenone, were only found in the treatment under full sunlight, while numerous others were exclusive to the different shading treatments. The yield and chemical composition of the essential oil of T. riparia is influenced by the level of shading.

Catalytic Oxidation of Pahs in Wastewater / Katalityczne Utlenianie Wwa w Ściekach

The aim of the investigations was to determine the effectiveness of the removal of 4, 5 - ring PAHs from coking wastewater using dihydrogen dioxide in the presence of a cobalt, platinum or titanium catalyst. A dose 7.4 mL of dihydrogen dioxide in the amount of and 14.8 mL/L of the analyzed sample were added to the samples. The samples were shaken and stored under laboratory conditions for 12 hours. The concentration of PAHs before and after the oxidation process were determined. The quantitative and qualitative chromatographic analysis was carried out using a gas chromatograph coupled with a mass spectrometer (GC-MS). The total concentration of 8 PAHs before oxidation reached the value of 9150 ng/L The concentration of 4-ring compounds and 5-ring PAHs were equal to 6390 ng/L and 2760 ng/L, respectively. The highest decrease (93%) the sum of 8 hydrocarbons using a dose of oxidizer 7.4 ml/L and in the presence of titanium catalyst was achieved.

Passive sampling of airborne furan indoors by solid-phase microextraction

Furan may be formed in food under heat treatment and is highly suspected to appear in indoor air. The possible exposure to indoor furan raises concerns because it has been found to cause carcinogenicity and cytotoxicity in animals. To determine airborne furan, solid-phase microextraction (SPME) technique was utilised as a diffusive sampler. The Carboxen/Polydimethylsiloxane (CAR/PDMS, 75 μm) fibre was used, and the SPME fibre assembly was inserted into a polytetrafluoroethene tubing. Furan of known concentrations was generated in Tedlar gas bags for the evaluation of SPME diffusive samplers. After sampling, the sampler was inserted into the injection port of a gas chromatograph coupled with a mass spectrometer (GC/MS) for thermal desorption and analysis. Validation of the SPME device with active sampling by charcoal tube was performed side by side as well. The charcoal tube was desorbed by acetone before analysis with GC/MS. The experimental sampling constant of the sampler was found equal to (9.93 ± 1.28) × 10−3 (cm3 min−1) at 25°C. Furthermore, side-by-side validations between SPME device and charcoal tube showed linear relationship with r = 0.9927. The designed passive sampling device for furan has the advantages of both passive sampling and SPME technique and looks suitable for assessing indoor air quality.

Analysis of Acidic Drugs in Swiss Wastewaters

Five acidic drugs (clofibric acid, ibuprofen, ketoprofen, mefenamic acid and diclofenac) were chosen in order to determine their behavior in a sewage treatment plant (STP). An analytical method using solid phase extraction (SPE) and a gas chromatograph coupled with a mass spectrometer (GC-MS) was used. The results show that four pharmaceuticals (clofibric acid, ketoprofen, mefenamic acid and diclofenac) are not well removed by treatment in Swiss STPs. Maximum concentration in the effluent was determined for mefenamic acid up to 1.0 µg/L. This component seems to be relevant in Swiss STPs effluents and we can expect its presence in surface waters.

Qualitative analysis of complex mixtures of VOCs using the inside needle capillary adsorption trap

An alternative sampling technique for fingerprint analysis of complex mixtures of petroleum-based products is presented. Fingerprint chromatograms of the volatile organic compounds (VOCs) for class 0-5 accelerants can be readily obtained using the recently developed inside needle capillary adsorption trap (INCAT) device. The concentration of VOCs from the static headspace of these complex mixtures, onto the adsorbing carbon coating of the INCAT device, avoids some problems associated with conventional headspace gas chromatography (HS-GC). The INCAT sampling method is a solventless extraction technique in which the analytes adsorbed inside the device are thermally desorbed inside the heated injection port of a gas chromatograph (GC), or a gas chromatograph coupled with a mass spectrometer (GC-MS). The presented method of active sampling with the INCAT device was used to obtain fingerprint chromatograms of the headspace of various gasolines, paint thinners, and lighter fluids. The static headspace chromatograms, from active sampling with the INCAT device, were compared with direct liquid injection of the samples. The INCAT chromatograms showed preferential adsorption of aromatic compounds over lighter, more volatile, but less polar compounds. Each class of the accelerant can be positively identified from the fingerprint chromatogram using only a few characteristic peaks. In addition, the ability to detect these volatile components of gasoline in aqueous samples at environmentally significant levels was also investigated.Key words: VOC, fingerprinting, INCAT, petroleum, headspace GC.

Qualitative analysis of complex mixtures of VOCs using the inside needle capillary adsorption trap

An alternative sampling technique for fingerprint analysis of complex mixtures of petroleum-based products is presented. Fingerprint chromatograms of the volatile organic compounds (VOCs) for class 0-5 accelerants can be readily obtained using the recently developed inside needle capillary adsorption trap(INCAT) device. The concentration of VOCs from the static headspace of these complex mixtures, onto the adsorbing carbon coating of the INCAT device, avoids some problems associated with conventional headspace gas chromatography (HS-GC). The INCAT sampling method is a solventless extraction technique in which the analytes adsorbed inside the device are thermally desorbed inside the heated injection port of a gas chromatograph (GC), or a gas chromatograph coupled with a mass spectrometer (GC-MS). The presented method of active sampling with the INCAT device was used to obtain fingerprint chromatograms of the headspace of various gasolines, paint thinners, and lighter fluids. The static headspace chromatograms, from active sampling with the INCAT device, were compared with direct liquid injection of the samples. The INCAT chromatograms showed preferential adsorption of aromatic compounds over lighter, more volatile, but less polar compounds. Each class of the accelerant can be positively identified from the fingerprint chromatogram using only a few characteristic peaks. In addition, the ability to detect these volatile components of gasoline in aqueous samples at environmentally significant levels was also investigated.

Determination of /V-Nitrosodiethanolamine in Dinoseb Formulations by Mass Spectrometry and Thermal Energy Analyzer Detection

A new method is described to determine trace quantities of N-nitrosodiethanolamine (NDElA) in aqueous diethanolamine (DElA) formulations and in oil solutions of dinoseb. A formate anion-exchange column is used in series with a cation-exchange column if there is DElA in the formulation. The eluate is then passed through a Clin Elut column. Depending on the concentration of NDElA in the sample, a packed silica-gel column is used to purify the extract further. This extract is analyzed on a liquid chromatograph coupled with a thermal energy analyzer (LC/TEA), using a mixture of methanol-hexane-methylene chloride containing 0.1% acetic acid (8 + 56 + 35) as the mobile phase. This solvent system gives good separation of NDElA from trace quantities of dinoseb remaining in the extract. The NDElA is also converted to the trimethylsilyl derivative and analyzed by gas chromatograph coupled with a mass spectrometer (GC/MS). Analyses of 11 commercial samples of dinoseb diethanolamine salt showed NDElA levels of 116-2409 ppm expressed relative to the weight of dinoseb. In contrast, analyses of 2 samples of organic solutions of technical dinoseb showed NDElA levels to be nondetectable and 0.3 ppm, respectively. Limit of detection by LC/TEA is 6.5 ng (0.5 ppm), and by GC/MS it is 0.02 ng (0.15 ppm). Recoveries from samples spiked at 0.514-1664 ppm range from 92.2 to 105.2%.