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Using 12 blank fruit matrices as solvents,15 organic phosphorus pesticides were prepared into mixed standard solutions of 0. 05, 0. 10,0. 20,0. 40 and 0. 80 mg / L,and compared with acetone solvent. The matrix effect of organic phosphorus pesticide residues in different fruit matrices was determined by gas chromatography. The results showed that 15 organic phosphorus pesticides exhibited varying degrees of matrix effects in 12 fruit substrates,with most pesticides exhibiting matrix enhancement effects,and there was no necessary correlation between pesticides and concentrations. Therefore,when conducting the detection of organic phosphorus pesticide residues in fruits,it is recommended to use a matrix instead of acetone as the solvent for standard preparation,which can greatly reduce the interference of the matrix on the detection results and improve the accuracy of the detection results. [ABSTRACT FROM AUTHOR]

The objective of this research was to study sample preparation techniques for reducing interference before analyzing six types of short-chain organic acids: acetic acid, propionic acid, isobutyric acid, butyric acid, isovaleric acid, and valeric acid, using gas chromatography (GC) from coffee samples brewed with a moka pot. The sample preparation used a fivefold dilution of the sample with methanol and deionized (DI) water, then separated the larger particles using a centrifuge, and cleaned the sample using an automated solid-phase extractor with Sep-ed C18 cartridges at a loading rate of 0.1 mL/min and sample volume of 5 mL. The results from the study of the physical characteristics of the samples before and after preparation showed a reduction in particle size from 6.78±4.69 μm to 1.40±0.74 μm. The values for red color intensity, yellow color intensity, and yellowness index decreased, while brightness and whiteness index increased significantly with a statistical significance at P < 0.05. The method's usability yields an adequately broad analytical range, with a linear correlation coefficient (r) > 0.9997. The detection limit was in the range of 2.5-10 mg/L, and the quantification limit was in the range of 5-20 mg/L. The recovery rate ranged from 93.8±3.6% to 104.3±1.8% and the reproducibility was in the range of 1.6-4.7%, which was acceptable. Furthermore, the qualitative analysis using GC-MS identified the area under the graph ranging from 36.4% to 50.4% and the quantitative analysis, calculated per coffee bean weight, using of GC-FID revealed that the total content of organic acids to be in the range of 3.08-7.92 g/kg. [ABSTRACT FROM AUTHOR]

Regular monitoring of water quality is essential for providing clean drinking water and protection of aquatic environments. The aim of the current study is to evaluate the quality and effects of low biodegradability, accumulation of heavy metals, and organic compounds on the running water sources of the district of Jhal Magsi. The concentrations of herbicides (DDT (2,4 D) and Cyanazine) and insecticides (chlorpyrifos, Aldrin, and Dieldrin) were determined by gas chromatography and the concentrations of heavy metals (Pb and Cd) and trace elements (Zn and Mn) were detected by anatomic absorption spectrophotometer. E. coli and P. aeruginosa were identified by Gram staining and biochemical tests. DDT (2,4 D), Cyanazine, Chlorpyrifos and Aldrin & Dieldrin were detected at 0.9±0.058, 0.08±0.006, 1.01±0.577 and 1.1±0.577 mg L-1 respectively; these values were higher than WHO safety limits. The heavy metals Pb and Cd were detected in all the samples and the highest range for Pb was 2.03±0.577 mg L-1, while that for Cd was 0.48±0.058 mg L-1. Trace elements Zn and Mn concentrations were 0.305±0.058 and 0.99±0.058 mg L-1, respectively. E. coli and P. aeruginosa were identified with 51.51 and 48.48%, respectively. The presence of higher concentrations of pesticides and heavy metals and their synergistic effect indicate a risk for both human health and aquatic organisms. Therefore, continuous monitoring of heavy metals and pesticides is necessary in the water reservoir of Jhal Magsi to ensure drinking safety. Bacterial assessment can aid in accepting bioremediation processes in water. [ABSTRACT FROM AUTHOR]

The Mud Logging Unit is a unit used to monitor information from cuttings carried by circulating drilling mud. This Final Report has the objectives, namely: to determine the existence of a productive zone (Payzone) based on the parameters of the DVS-04 well drilling, to determine the payzone by cutting analysis, to identify the type of hydrocarbons in 2 payzones based on GWR, LHR and OCQ calculations. The parameters used in determining the payzone are WOB, ROP, Total Gas Detector, Gas Chromatograph, Cutting Analysis, GWR Calculation, LHR and OCQ. The productive zone (Payzone) is a reservoir rock that contains exploitable amounts of fluid, generally located in a permeable layer. The data used for payzone analysis are: ROP, WOB, total gas detector, gas chromatograph (C1-C5), Final Well Report and Mud Log. The field stratigraphy consists of the Cisubuh Formation, the Parigi Formation, the Upper Cibulakan Formation, the Baturaja Formation, the Talangakar Formation, and the Jatibarang Formation, in the DVS-04 well drilling program targeting the payzone, namely the Upper Cibulakan Formation. After plotting, the calculation results obtained for 2 payzones at a depth of 1363-1397 mMD and 1505 – 1540 mMD in sandstones and limestones. Payzone A and payzone B have GWR values of 37.72 (Payzone A) and 24.28 (Payzone B) in the range of 17.5-40 which identify zones containing oil with a GWR greater than the LHR. Both payzones A and B in the cutting and oil show analysis yielded information on the hydrocarbon content of the two productive rocks, namely sandstones and limestones. In the analysis based on detailed data, the best payzone is payzone B which is located at a depth of 1505 – 1540 meters in the upper Cibulakan formation. [ABSTRACT FROM AUTHOR]

In this Application Note, a versatile and reliable measurement system for photoelectrochemical investigations is described which aims to assist scientists in obtaining reproducible photoelectrochemical data of high quality, including the solar‐to‐hydrogen (STH) efficiency. Specifically, it addresses the parameters irradiation quality, reaction temperature, and gas measurement. The setup is designed to exclude stray light and uses a solar‐grade mirror to reflect the light of a vertical solar simulator on the electrochemical cell. The light quality in the setup (»AAA«, IEC 60904‐9) is close to the classification of the solar simulator itself. The temperature in the electrochemical cell is controlled with an external Peltier element and can be kept constant in the range of 20–45°C. The influence of reaction temperature on the photocurrent of a WO3 photoanode is demonstrated. The gaseous reaction products are analyzed with a mobile gas chromatograph, using an automated measurement routine with discontinuous sampling from the electrochemical cell. The system is applied to determine the Faraday and STH efficiencies of a copper indium gallium selenide photocathode. [ABSTRACT FROM AUTHOR]

Sarin is considered to be an instrument for chemical terror by the extremist organizations due to the availability of technologies and components for its production. This fact became evident after the use of sarin by several members of the extremist organization «Aum Shinrikyo» for air infection of the capital`s subway in 1995 in Japan and by ISIL bands in Syria in 2013. Because of its physical and chemical properties, as well as its ability to be dissolved in water in any ratios, sarin can infect water sources for the long period of time. But the sensitivity of flame photometric detectors (FPD) is not always sufficient for the analysis of water samples for the presence of sarin, its precursors and products of destruction, especially in cases of necessity to detect the concentrations less than 0,03 ppm (3×10-5 mg/ml). We have found out that higher sensitivity of the detector can be achieved in case of the increase of the gas carrier (helium) pressure in the injector up to 25 psi, and the temperature – to 250 °C, single-segment temperature rise in the thermostat with a speed of 10 °C/min from 40 °C (1 min) to 280 °C (5 min) at a hydrogen stream in PFD – 75 ml/min, air – 100 ml/min, helium – 60 ml/min. In comparison with the initial method, the offered one is more sensitive in case of sarin concentration in water in the range from 6×10-6 to 1×10-4 mg/ml to 1,7 times. The approbation of the offered optimal parameters was carried out during the gas chromatographic detection of sarin in water samples during the OPCW Proficiency Tests, during the analysis of arbitration samples, during the scientific research and the obtaining of national accreditation of the Laboratory of Chemical Analytical Control of the 27 Scientific Centre of the Minstry of Defence of the Russian Federation. These parameters can be used successfully during the studies of any organophosphorous chemicals by GC analysis with flame photometric detection.

Aroma is a promising quality factor for rice grain that impacts consumer acceptability. The principal volatile compound that adds Basmati rice fragrance is 2-acetyl-1-pyrroline (2AP). Milled White rice of 04 promising varieties i.e., Super Basmati, Basmati-515, Basmati 2000and Basmati 370 were evaluated for volatile compounds by gas chromatography (GC) coupled with Solid Phase Micro Extraction unit (SPME) using Flame Ionizing Detector (FID). Six volatile compounds (nonanal, decanal, and alcohols such as benzyl alcohol, indole) were identified in the tested varieties, among them 2-AP is only present in aromatic rice varieties. This study confirmed the occurrence of 2-AP in all studied varieties with highest concentration in Super Basmati followed by Basmati-515, Basmati 2000 and Basmati 370.

With the importance of cocoa beans and its products, it is imperative to know whether the levels of pesticides residues are kept below the recommended levels to minimize the risk to human health. This study investigates the incidence and levels of organochlorinated pesticide residues in cocoa beans from eighteen selected cocoa farms in Ekiti State, Nigeria. Method 3550C of USEPA was employed to extract the pesticides from the samples, while a Gas Chromatography coupled with Electron Capture Detector (GC-ECD) was used for pesticides identification and quantification after careful extraction and clean-up on silica gel. The mean OCPs concentrations ranged from 0.0003 μg/g (α-BHC) to 0.163 μg/g (endosulfan sulphate) with α-BHC as the most frequently found pesticide residue. The concentration levels of lindane, α-BHC, p,p’-DDT, p,p’-DDD, heptachlor, heptachlor-epoxide and endosulfan II were below the maximum residual limit (MRL) in food as reported by European Union, while 0.92%, 2.78%, and 4.6% of endosulfan I, (β-BHC and δ-BHC) and (aldrin and dieldrin) respectively were above the MRL. The detectable levels of OCPs in the beans make it inevitable to conduct regular monitoring so as to ensure that the levels remains below prescribed limits by national and international standards. [ABSTRACT FROM AUTHOR]

A novel method to quantify 1,4‐dioxane in finished cleaning products using headspace gas chromatograph with mass spectrometry (HS GC/MS), single ion monitoring, and a fully deuterated internal standard has been developed. The method generates very linear calibration curves with a R2 of at least 0.99, excellent accuracy with spike/recovery of 97%–102%, and effective precision of 1%–7%RSD for different cleaning products. The method also produces an instrument limit of quantitation (LOQ) of <20 ppb, and sample LOQ of <100 ppb. The method robustness was demonstrated with a ten‐lab round‐robin exercise that showed that even with some unexpected deviations from the method, excellent analytical results were obtained from the different labs. This new method will be valuable to evaluate consumer products impacted by government regulation to limit 1,4‐dioxane concentrations in complex matrices. [ABSTRACT FROM AUTHOR]

This study report the concentration levels and distribution pattern of the organochlorine insecticides residues in water and sediments of the Harchandpur pond. The water samples were collected from three different sites and analyzed for their insecticide profile. We used liquid-liquid extraction followed by GC-ECD for the determination of these compounds. Out of 18 water samples analysis, the average residue concentration for all the six insecticides was between 0.45 and 11.11 µmg/l. The residues of dieldrin 11.11 µmg/l. constitutes the major component followed by heptachlor, aldrin, gHCH permethrin and DDT. The percent occurrence was the highest for aldrin>permethrin, dieldrin>gHCH> heptachlor>DDT. [ABSTRACT FROM AUTHOR]

Copyright of Silicone Material is the property of Silicone Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plasma electrolytic oxidation (PEO) was performed on 60 vol.% SiCp/2009 aluminum matrix composite under different voltages in silicate solution and NaF solution, respectively. Anode gas evolutions under different conditions during the PEO process were evaluated by the gas chromatograph, optical emission spectroscopy, scanning electron microscope, X-ray diffraction and inductively coupled plasma atomic emission spectroscopy. The anode gas released at different voltages in both solutions contained H2, O2 and trace CO. The H2 concentration increased with the increase of voltage in the silicate solution, and then it was kept at 75–80 vol.% in the range from + 480 V/–0 V to + 520 V/–0 V, which was related to the appearance of strong discharge sparks. The H2 concentration of the anode gas in NaF solution was much lower than that in the silicate solution due to the weak discharge. The excessive H2 was caused by nonfaradaic reactions in the plasma discharge region such as thermal decomposition of water. Meanwhile, the O2 in anode gas mainly came from thermal decomposition of water in plasma discharge region and traditional electrochemical reactions in nondischarge region. In addition, SiC reinforcement particles were oxidized in plasma discharge channels with the temperature up to 5000 K, accompanied by the release of trace CO. Furthermore, CO2 was hardly detected due to the effect of H2 reduction in the discharge channels. [ABSTRACT FROM AUTHOR]

The oil industry is one of the causes of environmental pollution by oil spills due to drilling and extraction. In case of oil leakage from oil wells to soil and then groundwater, it leads to the movement of pollutants and the spread of pollution by groundwater. In the study area, due to the existence of two oil fields, Qaleh Nar and Balaroud, upstream of Dez Dam and their inclined slope towards Dez Dam Lake, the possibility of spreading oil pollutants through groundwater to Dez Dam was investigated and the development of new risk assessment method was also performed. Water samples from groundwater and Dez dam reservoir were analyzed for total petroleum hydrocarbon concentration. A Gas Chromatograph (GC-FID) was used to measure the concentration of TPH in samples. The probability of carcinogenic and non-carcinogenic diseases has been assessed according to the EPA standard. The results revealed non-carcinogenic risk (HQ) in groundwater and in Dez reservoir respectively with the highest C10 values of 38.54 μg/ml and 1.9 μg/ml. The new equation was formulated with the factor of importance and C10 was taken as the most important pollutant. The results of new method (HRA) indicated non-carcinogenic risk for C10 was highest in groundwater (well: 20.7, spring 1:22.5, spring 2:8.4, and spring 3:7.09 μg/ml) and dam reservoir in sample C (1.1 μg/ml), exceeding the safety limit of 0.6 (in the new formula). This study confirmed the entry of TPH into the reservoir of Dez Dam through groundwater and the risk of non-carcinogenic diseases. [ABSTRACT FROM AUTHOR]

For on-site analysis of surface materials on the Moon, planets, and small bodies and for the monitoring of air quality in crewed spacecraft, we have developed a portable gas chromatograph (GC) equipped with a ball surface acoustic wave (SAW) sensor. In this study, we fabricated a 10 cm cube GC that implements the forward flush method using two metal micro-electro-mechanical-system columns coated with different stationary phases in microchannels fabricated by wet etching and diffusion bonding of stainless-steel plates. Using this GC, we succeeded in analyzing 10 kinds of gas within 10 min. In addition, for the application of the ball SAW GC on the ground, we also developed a palm-sized GC with a single metal capillary column and used it in the analysis of the headspace gas of sake. We showed that the ratio of peak areas differed among odorants depending on the brand and brewing process of sake. [ABSTRACT FROM AUTHOR]

Ethnobotanical studies have reported the traditional medicinal uses of Acacia senegal (L.) Willd. and Argania spinosa (L.) Skeels against kidney stone formation and other chronic kidney diseases. The present work is undertaken to study the litholytic activity and the inhibiting activity of calcium oxalate crystallization by bioactive compounds identified in Argania spinosa (L.) Skeels press-cake (residue of Argan oil) and in Acacia senegal (L.) Willd. The litholytic activity was studied in vitro on cystine and uric acid stones using a porous bag and an Erlenmeyer glass. The study of the inhibiting activity of calcium oxalate crystallization, was based on temporal measurements of the optical density, registered at a 620 nm wavelength for 30 min using an ultraviolet–visible spectrophotometer. The silylation method was performed to identify phytochemicals, followed by gas chromatography coupled with mass spectrophotometry (GC/MS) analysis. The results show significant litholytic activity of Argania Spinosa press-cake hydro-ethanolic extract on uric acid and cystine stones, respectively, with dissolution rates (DR) of 86.38% and 60.42% versus 3.23% and 9.48% for the hydro-ethanolic extract of Acacia senegal exudate. Furthermore, the percentages of nucleation inhibition are 83.78% and 43.77% (p ˂ 0.05) for Argania spinosa and Acacia senegal, respectively. The results point to the detection of 17 phytochemicals in Argania spinosa press-cake extract, the majority of which are phenolic acids and have potent anti-urolithiatic action. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyl (PCB) congeners in groundwater samples from selected fuel stations in Ado-Ekiti, Southwestern Nigeria, were analyzed to investigate the impact of increased anthropogenic activities. Qualitative and quantitative evaluations of the PAHs and PCBs were done using gas chromatography coupled with appropriate detectors. The PAHs concentrations ranged from ND − 0.98 mg/L, while the PCBs ranged from ND − 164 µg/L. The study reflected that NNPC sampling point had the least contaminated with PCBs, whereas 5Os evinced the highest. The concentrations of the high molecular weight PAHs were generally high compared to low molecular weight PAHs. Using specific ratio distribution, PAH fingerprints suggest pyrogenic origin. Further statistical analysis revealed that 69.0% of the PCBs congeners showed significant difference among the sampling sites with RIHD and 5Os contributing values responsible for the significant levels, while Chi-square revealed no significant difference in the PAHs levels. [ABSTRACT FROM AUTHOR]

The safe and reliable operation of Gas Insulated Switchgear (GIS) equipment is very important to the entire power grid. Early detection and timely treatment of GIS equipment internal insulation defects is the main way to prevent large-scale power outages. Partial discharge (PD) monitoring is one of the most important ways to find insulation defects. SF6 gas decomposes under PD to generate a series of characteristic products. By detecting the types of gas decomposition components in GIS and their content changes, the PD inside GIS equipment can be effectively monitored. This method is not subject to complex electromagnetic interference on site and has become the focus of research in this field. In this paper, an experimental platform for SF6 decomposition under partial discharge caused by free particles is designed, and a 240-hour partial discharge experiment under 5 voltage levels is carried out. Studies have shown that the decomposition products of SF6 under the action of GIS partial discharge include CO2, CF4, H2S and SO2. These four decomposition products can be used to reflect the decomposition of SF6 inside the GIS chamber, and the content of decomposition products and gas production. The rate increases with the increase of the applied voltage and the extension of the experiment time. When CO2 and SO2 are generated inside the GIS gas chamber, there may be an initial insulation failure. If H2S and CF4 are generated inside the GIS gas chamber, the failure is more serious and should be repaired in time. [ABSTRACT FROM AUTHOR]

The studies of Acetochlor mainly focus on the detection of environmental residues and the assessment of behavioral patterns in the environment, but there is little information on the studies related to Acetochlor occupational exposure. In particular, there are no reported methods for detecting Acetochlor concentrations in the air of the workplace. This research established the method about the detection of Acetochlor in the air of workplace. As for the desorption efficiency of other various tube filler materials and desorption solvents selected in the study did not meet the requirements of the study, the Acetochlor in the air was collected by polyurethane foam sample tube, and the sample was extracted by methanol solution and analyzed by gas chromatograph. Good linearity (R2 > 0.999), high repeatability (0.7–7.1%), good recoveries (93.5–107.6%) and low limit of detection of acetochlor (0.0006 mg/m3) was obtained. And, the samples were stable within 30 days. The positive detection rate of fixed samples in workplace was 59.4% (n = 37), and the positive detection rate of individual samples was 94.7% (n = 19). A validated polyurethane foam-gas chromatography method was established for the separation and analysis of Acetochlor. The developed method is simple, efficient and suitable for the determination of Acetochlor concentration in the workplace. [ABSTRACT FROM AUTHOR]

A mine gas chromatograph pressure, temperature, injection and switch control system with network control function has been developed. The cloud has the remote control function of the chromatograph, and the user can use the mobile phone, tablet and other tools before use. The tool remotely controls the chromatograph through the network, and stabilizes the instrument in advance. When it arrives in the laboratory, it can be put into operation immediately, which improves the work efficiency.

In order to provide the qualitative data for the 20 commercially available krill oil supplementary products, the levels of omega-3 polyunsaturated fatty acids (PUFA) such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), fatty acid compositions, and chemical indices, including acid values, of the supplements, were determined. The acid values ranged from 7.4 to 43.7 mg of potassium hydroxide (KOH)/ g of oil. The relative percentages of EPA and DHA in the oils ranged from 14.2 to 34.8 % (w/w). Although all 20 krill oil supplements used 100% krill oil as raw material, the fatty acid composition of 4 samples differed from typical krill oil in terms of the content of myristic acid (C14:0), palmitic acid (C16:0), palmitoleic acid (C16:1), linoleic acid (C18:2, n-6), and eicosenoic acid (C20:1, n-9). Accordingly, the Ministry of Food and Drug Safety recently standardized linoleic acid (3% or less) and myristic acid (5-13%) as part of the fatty acid components of krill oil. This study provides a reference for analyzing the chemical and nutritional properties and evaluating the adulteration of krill oil supplements in the Korean market.

A certified reference material (CRM) of sulfur dioxide (SO2) gas, with a certified value of purity, was developed for the preparation of primary reference gas mixtures of SO2 in nitrogen (N2) gas. Impurity analyses by "subtraction method" were performed using a gas chromatograph (GC) with a thermal conductivity detector (TCD), a GC with a flame ionization detector (FID), and a Fourier transform infrared spectrometer (FT-IR), all calibrated with gas mixtures traceable to the Internal System of Units (SI). First, qualitative analysis using the FT-IR was performed on two samples of liquefied SO2 of different quality grades, contained in gas cylinders. Using the FT-IR and the GC-TCD, carbon dioxide (CO2) was detected in the lower- and higher-grade cylinders at approximately 0.5 cmol/mol and 5 µmol/mol, respectively. The FT-IR did not detect any sulfur compound peaks, other than SO2, in the higher-grade sample. Other atmospheric constituents such as N2, oxygen (O2), water (H2O), argon (Ar), and methane (CH4) were also tested for in this sample. The detection limit of H2O in the FT-IR was 49 µmol/mol, while those of N2, O2, Ar, by the GC-TCD were a few µmol/mol, and CH4, using the GC-FID, were better than 1 µmol/mol. The high detection limit of H2O was due to large baseline fluctuations when measuring the FT-IR spectrum of the SO2 gas. Responses corresponding to these analytes were not detected or were detected below the detection limits. For an estimation of purity by the subtraction method, each reported mol fraction was regarded as half the value of each detection limit, except for the CO2. The purity and its expanded uncertainty [k = 2] of the high-purity SO2 gas by the subtraction method were 99.9964% and 0.0028%, respectively. [ABSTRACT FROM AUTHOR]

Summary: A prediction model for hydrogen loss rate (HLR) of coating zirconium hydride at 873 K based on Wagner's model was established using gas chromatograph. A continuous and dense coating of zirconium hydride with bilayer structure was prepared by phosphation‐oxidation method. The oxidation weight gain of coating zirconium hydride specimens at 873 K in a mixture atmosphere of CO2 and He was investigated. The oxidation weight gain law was obtained by fitting Wagner's model, and the release equation of CO were further deduced. The concentration of H2 and CO in the gas phase was measured by gas chromatograph in the closed system under the same conditions. The optimized HLR of coating zirconium hydride was obtained by deducting the amount of CO generated by the reaction of zirconium and CO2 using the release equation of CO. Fitted by Wagner's model, the dependence between optimized HLR and reaction time was obtained, and the loss amount of hydrogen at any moment can be calculated by extrapolated and integrated, thus a prediction model was established. Based on the model, the HLR of coating zirconium hydride is 0.97% in 1 year. Highlights: A prediction model for hydrogen loss rate of coating ZrHx at 873 K was established using gas chromatograph.A continuous and dense coating of ZrHx with bilayer structure was prepared by phosphation‐oxidation method.Fitted by Wagner's model, the equation of hydrogen permeability rate was obtained.The prediction model was further optimized by deducting the amount of CO produced by the reaction of Zr in CO2. [ABSTRACT FROM AUTHOR]

The corrected stem CH SB 4 sb uptake (-15.1 ± 1.9 g CH SB 4 sb m SP -2 sp h SP -1 sp ) did not significantly differ from the stem CH SB 4 sb uptake calculated initially (-15.6 ± 2.0 g CH SB 4 sb m SP -2 sp h SP -1 sp ). FTIR, gas chromatograph, greenhouse gas, interference, methane (CH4) flux, nitrous oxide flux, tree stem gas exchange, volatile organic compound (VOCs) Keywords: FTIR; gas chromatograph; greenhouse gas; interference; methane (CH4) flux; nitrous oxide flux; tree stem gas exchange; volatile organic compound (VOCs) EN FTIR gas chromatograph greenhouse gas interference methane (CH4) flux nitrous oxide flux tree stem gas exchange volatile organic compound (VOCs) 2100 2104 5 05/20/21 20210615 NES 210615 Data availability The datasets analyzed during this study are available from the corresponding author upon reasonable request. In order to include representatives of all six tree species studied and measurements of CH SB 4 sb uptake rates across the entire range detected for the trees, we examined the potential VOC interference on three to five stem flux measurements from the following tree species: I Syzygium borbonicum i ( I n = i 4), I Doratoxylon apetalum i ( I n i = 4), I Antirhea borbonica i ( I n i = 5), I Homalium paniculatum i ( I n i = 3), I Mimusops balata i ( I n i = 3) and I Labourdonnaisia calophylloides i ( I n i = 3). [Extracted from the article]

ZIF-67@NH 2 –SiO 2 composites were prepared by loading the metal-organic frameworks ZIF-67 on amino modified SiO 2 gel particles (NH 2 –SiO 2 , 80–100 mesh) through layer-by-layer self-assembly method. Systematic investigation on the effects of ZIF-67 loading amounts on NH 2 –SiO 2 packed stainless steel chromatographic column (specification 1.0 m×2.0 mm I.D.), the flow rate of He as carrier gas and the injection amount of mixed gas (H 2 /D 2) on the hydrogen isotope H 2 /D 2 separation performance at liquid nitrogen temperature, unraveled the optimal conditions for H 2 /D 2 isotope separation. The results showed that the optimal stationary phase materials under the optimized conditions can effectively separate H 2 and D 2 with separation resolution R = 1.52 and the separation time t = 10.15 min. The superior performance of the ZIF-67 is tentatively thought to be due to kinetic quantum sieving (pore size 3.3 Å) effect and chemical affinity sieving effect of Co ion in ZIF-67. [Display omitted] • ZIF-67 is grown on amino modified SiO 2 using layer-by-layer self-assembly method. • The obtained optimal ZIF-67@NH 2 –SiO 2 composite is used as stationary phase material. • The composite is loaded into a 1-m chromatographic column (2.0 mm I.D.). • H 2 /D 2 can be effectively/efficiently separated under liquid N 2 temperature. [ABSTRACT FROM AUTHOR]

This paper describes the development of a gas chromatography-quadrupole mass spectrometry system attached to a differential-pumping-type environmental cell of the reaction science high-voltage electron microscopy instrument at Nagoya University to distinguish unambiguously between different gas species with the same mass-to-charge ratio. Several model experiments were used to verify the efficacy of the newly proposed system, confirming its ability to analyse the atomic-level structural changes during heterogeneous catalysts and the associated gas-reaction kinetics simultaneously, providing new insights into operando measurements in the field of environmental transmission electron microscopy. Graphical Abstract., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Japanese Society of Microscopy.)

Aiming at the application problems encountered by operators in the use of mining gas chromatographs, the paper uses the factor analysis method and elaborates the gas chromatograph in detail from five parts including the gas path system, sampling system, separation system, temperature control system and detection recording system. Moreover, the paper introduces the role of each part in the gas chromatograph and the corresponding impact on the gas chromatograph in the sample analysis.

Ion mobility spectrometers can detect gaseous compounds at atmospheric pressure in the range of parts per trillion within a second. Due to their fast response times, high sensitivity, and limited instrumental effort, they are used in a variety of applications, especially as mobile or hand-held devices. However, most real-life samples are gas mixtures, which can pose a challenge for IMS with atmospheric pressure chemical ionization mainly due to competing gas-phase ionization processes. Therefore, we present a miniaturized drift tube IMS coupled to a compact gas chromatograph for pre-separation, built of seven bundled standard GC columns (Rtx-Volatiles, Restek GmbH) with 250 μm ID and 1.07 m in length. Such pre-separation significantly reduces chemical cross sensitivities caused by competing gas-phase ionization processes and adds orthogonality. Our miniaturized GC-IMS system is characterized with alcohols, halocarbons, and ketones as model substances, reaching detection limits down to 70 pptv with IMS averaging times of just 125 ms. It separates test mixtures of ketones and halocarbons within 180 s and 50 s, respectively. The IMS has a short drift length of 40.6 mm and reaches a high resolving power of RP = 68. [ABSTRACT FROM AUTHOR]

Levels of polycyclic aromatic hydrocarbons (PAHs) in fresh and smoked Clupea herengus (shawa) and Hake (panla) fish commonly consumed in Ekiti State, Nigeria were investigated using gas chromatographic method. Effect of smoking on the PAHs level was also considered. The PAHs concentration ranged from 0.0001 µg/kg Acenapthene and Indeo (1,2,3-cd) pyrene to 0.240 µg/kg (Benzo (a) pyrene) for fresh unsmoked Clupea herengus (SF), 0.0001µg/kg Acenapthene and Anthracene to 0.638 µg/kg Benzo (b) fluoranthene for smoked C. herengus (SF), 0.0001 µg/kg Acenapthene, Anthracene, Fluoranthene and Benzo(ghi) perylene and Indeno(1,2,3-cd)pyrene to 0.171 µg/kg (Benzo (a) pyrene) for fresh Hake (panla) fish (PF) and 0.0001 µg/kg Indeno(1,2,3-cd)pyrene to 0.966 µg/kg pyrene for smoked Hake (panla) fish (PS) samples. Results also revealed TPAHs levels in the smoked fish were 62.3-62.5% times higher than the fresh. Values of PAHs levels in the fish samples were below EU-regulatory limits (30µg/kg) for PAHs. Hazard index and lifetime excess carcinogenic risk of the samples revealed no potential cancer and mutagenic risks. [ABSTRACT FROM AUTHOR]

In this paper, the measurement of water and oxygen distributions along the modified parallel serpentine cathode flow channels has been performed using a gas chromatograph (GC). Generally, it is difficult to directly profile oxygen and water distributions where water concentration nearly reaches saturation levels. Here, the measurement of high levels of water saturation in cathode channels was carefully performed according to operating conditions such as cell voltage and air stoichiometry. GC measurement was also carried out to understand the oxygen and water distributions under channel flooding conditions. In addition, the oxygen and water vapor distributions by GC measurements for the base-line case were compared with computational fluid dynamics (CFD) simulation results. For the entrance of the flow channel, the simulated results show a good agreement with the measured results. However, some discrepancy between calculated and experimental results is found for the flow channels near the cathode outlet. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article presents the classification of the gas stream contaminant types in noble gas enrichment and purification units. For the safe and efficient system operation, it is necessary to choose the right method of multicomponent mixture separation and the optimal corresponding equipment operating parameters, also to offer a method to verify the absence of the undesirable contaminant in the gas stream. The methods to control the obtaining of required noble gas purity during cryogenic rectification are indicated. Application of various gas analysis methods is necessary to obtain high purity (up to 99.9999%) gases: gas chromatography, mass spectrometry, and their combination. The effect of the state of various components of a gas chromatograph on the analysis result are discussed. Recommendations are provided for noble gas analysis methodology, including the conditions for the determination of trace impurities. The article presents examples of practical application of gas chromatography to control the processes of noble gas enrichment and purification, using the example of production of pure xenon. [ABSTRACT FROM AUTHOR]

The study investigated the concentration of pesticides in cotyledon and testa of Moringa oleifera collected from a garden in Ado-Ekiti. Gas chromatographic analysis was employed for the pesticides determination after careful extraction and florisil cleanup. The concentration (µg/kg) of pesticides in the cotyledon ranged from 0.031 (2, 4, 6-trichlorophenol) to 0.313 (oxamyl), while the testa ranged from 0.004 (pyriproxyfen) to 1.99 (cypermethrin). Oxamyl, cyanazine, fenvalerate, chlorpyrifos, aldrin and phosphine were the most concentrated pesticides with trend of cypermethrin ˃oxamyl ˃ cyanazine ˃ fenvalerate ˃ phosphine ˃ chlorpyrifos ˃ aldrin. 55.9% of the pesticides had values in the cotyledon greater than the testa. Residual levels of these pesticides were below the maximum permissible limits set by the European Union (EU) Commission. [ABSTRACT FROM AUTHOR]

The study investigated levels of polycyclic aromatic hydrocarbons (PAHs) in fresh and smoked body parts of Clarias gariepinus in Nigeria. Effect of smoking on the PAHs level was also considered. The mean PAHs concentration ranged from 0.0005 µg/kg [indeno (1,2,3-cd)pyrene] to 2.24 µg/kg (fluoranthene, pyrene) and 0.0009 µg/kg [indeno(1,2,3-cd)pyrene] to 10.2 µg/kg (pyrene) for fresh and smoked fish samples respectively. Total PAHs concentrations in the fresh parts were in the order: HF > MF > LF, whilst the smoked showed LS > HS > MS. Results also revealed TPAHs levels in the smoked fish were 70–80% times higher than the fresh. Significantly high accumulation of PAHs was found in smoked parts as compared to fresh. Values of PAHs levels in the fish were below EU-regulatory limits (30 µg/kg) for PAHs. Risk associated with the samples revealed no potential cancer and mutagenic risks. [ABSTRACT FROM AUTHOR]

Hydrogen is increasingly receiving a primary role as an energy vector in ensuring the achievement of the European decarbonization goals by 2050. In fact, Hydrogen could be produced also by electrolysis of water using renewable sources, such as photovoltaic and wind power, being able to perform the energy storage function, as well as through injection into natural gas infrastructures. However, hydrogen injection directly impacts thermodynamic properties of the gas itself, such as density, calorific value, Wobbe index, sound speed, etc. Consequently, this practice leads to changes in metrological behavior, especially in terms of volume and gas quality measurements. In this paper, the authors present an overview on the impact of hydrogen injection in natural gas measurements. In particular, the changes in thermodynamic properties of the gas mixtures with different H2 contents have been evaluated and the effects on the accuracy of volume conversion at standard conditions have been investigated both on the theoretical point of view and experimentally. To this end, the authors present and discuss the effect of H2 injection in gas networks on static ultrasonic domestic gas meters, both from a theoretical and an experimental point of view. Experimental tests demonstrated that ultrasonic gas meters are not significantly affected by H2 injection up to about 10%.

Pubertal molt is a vital stage in the cultivation of mature female crabs in the aquacultural industry of Scylla paramamosain. Since fasting occurs during molting, which requires a large supply of energy, internal energy reserves are critical. However, the dynamics of energy supply during pubertal molt is not clear. This study focuses on the variations of carbohydrates and lipids in serum during the pubertal molt of S. paramamosain via a metabolomics approach. Eleven lipid or carbohydrate metabolic pathways were significantly influenced postmolt. A remarkable decrease in carbohydrates in serum suggested that free sugars were consumed for energy. A significant decrease in glucose and alpha-d-glucosamine 1-phosphate showed that chitin synthesis exhausted glycogen, resulting in insufficient glucose supply. An increase in l-carnitine and acetylcarnitine, and a significant decrease in 15 fatty acyls and 8 glycerophosphocholines in serum indicated that carnitine shuttle was stimulated, and β-oxidation was upregulated postmolt. In addition, astaxanthin, ponasterone A, and riboflavin in serum were significantly decreased postmolt. Eleven potential metabolite biomarkers were identified for pubertal molt. Taken together, carbohydrates and lipids were possibly major energy reserves in pubertal molt. This study suggests that an increase in carbohydrate and lipid levels in crab feed may alleviate the effects of fasting during molt and improve farm productivity in mature female crabs.

SF(6) has been widely used as an insulating and arc extinguishing medium in electric power equipments. Detection of gas decomposition products is an important means for condition monitoring and fault diagnosis. Trace H(2)O and O(2) have a significant influence on the species and concentrations of SF(6) decomposition products. It is important to explore the influence mechanism of trace H(2)O and O(2) on SF(6) decomposition products under arcing conditions. A series of SF(6) decomposition tests were carried out on a 40.5kV SF(6) circuit breaker, and a gas chromatograph and an electrochemical sensor were used to measure decomposed components. First, the H(2)O content remained constant, and the O(2) content and arcing energy changed in the tests. It has been found that the decomposition products of SF(6) are SOF(2), SO(2), CO, CO(2), CF(4), C(2)F(6) and C(3)F(8). Then, the O(2) content remained constant, and the H(2)O content changed. The decomposition products are mainly SOF(2), SO(2), CO and CO(2). Concentrations of all these decomposition products increase first and then tend to be stable slowly over time, but change differently with the increase of H(2)O and O(2) contents, because H(2)O and O(2) play different roles in the formation process of each decomposition characteristic components.

In this work, 1‐vinyl‐3‐butylimidazolium bis((trifluoromethyl) sulfonyl)imide modified Fe3O4 magnetic nanoparticles were prepared by "thiol‐ene" click chemistry. The morphology, composition, and structure of as prepared functional material was investigated with several technique. Such magnetic material was applied to magnetic solid‐phase extraction of pyrethroid pesticides, and the analytes were quantitatively analyzed by gas chromatography‐mass spectrometry. Significant parameters of proposed method, including adsorbents amount, vortexing time, solution pH, and eluent volume and type, were optimized. Under the optimized condition, this method exhibited good linearity in the range of 0.19–200 μg L−1 for resmethrin, 0.44–200 μg L−1 for bifenthrin, 0.35–200 μg L−1 for fenpropathrin, and 0.31–200 μg L−1 for cyhalothrin, with the correlation coefficients>0.9992, and low limits of detection (0.06–0.13 μg L−1, S/N=3). The method was successfully applied to quantitative determination of pyrethroid pesticides in environmental water sample with the satisfactory recovery ranging from 85.7 % to 110.4 % and relative standard deviations ranging from 1.3 % to 6.6 %. The results indicated that the proposed magnetic solid‐phase extraction is a simple, efficient and time‐saving method. [ABSTRACT FROM AUTHOR]

The Support Laboratory of Nanofabrication of Yamaguchi University is a member of the Nanofabrication Platform Consortium in the Nanotechnology Platform Japan. Our laboratory features the desorption gas analysis of materials and devices based on the original vacuum technology in addition to the nanofabrication. In this paper, an operand desorption gas analysis system (apparatus for dynamic thermal desorption spectroscopy), which is one of our gas analysis systems, is explained. The advantage of this system is that it enables a desorption gas analysis of an operating device under an approximately atmospheric pressure (0.1 to 0.2 MPa) using gas chromatography/mass spectrometry, in contrast to a sample placed in a vacuum in a conventional apparatus for thermal desorption spectroscopy. Moreover, two measurement examples (DC electric motor and solar cell) using this operand gas analysis system were described. In the DC motor, the main desorbed gas from the motor behaved similarly to the motor electric power with the occurrence of failure or stop caused by heating. In the solar cell, from the comparison of the temperature dependence between the open circuit voltage and the main desorbed gases from the solar cell, the temperature durability of the sealing part is confirmed to be related to the electron generation efficiency. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

SF6 has been widely used as an insulating and arc extinguishing medium in electric power equipments. Detection of gas decomposition products is an important means for condition monitoring and fault diagnosis. Trace H2O and O2 have a significant influence on the species and concentrations of SF6 decomposition products. It is important to explore the influence mechanism of trace H2O and O2 on SF6 decomposition products under arcing conditions. A series of SF6 decomposition tests were carried out on a 40.5kV SF6 circuit breaker, and a gas chromatograph and an electrochemical sensor were used to measure decomposed components. First, the H2O content remained constant, and the O2 content and arcing energy changed in the tests. It has been found that the decomposition products of SF6 are SOF2, SO2, CO, CO2, CF4, C2F6 and C3F8. Then, the O2 content remained constant, and the H2O content changed. The decomposition products are mainly SOF2, SO2, CO and CO2. Concentrations of all these decomposition products increase first and then tend to be stable slowly over time, but change differently with the increase of H2O and O2 contents, because H2O and O2 play different roles in the formation process of each decomposition characteristic components. [ABSTRACT FROM AUTHOR]

Highlights • GO-poly AM-EDGMA monolithic fiber was fabricated for HS- SPME for the first time. • The polymeric fiber incorporated GO has bigger surface area and high temperature assistance. • The robustness of GO incorporated polymeric fiber facilitates high throughput automation. • The HS-SPME/GC-FPD method for the determination of OPEs deposited on soil is simple, sensitive and reproductive. Abstract A novel solid phase microextraction fiber named graphene oxide incorporated poly acrylamide-ethylene glycol dimethacrylate (GO-poly AM-EDGMA) monolithic fiber has been successfully prepared in a fused silica capillary tube (250 μm, i.d.) via thermally initiated polymerization using acrylamide (AM) as the monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinker, dimethylformamide dispersed by GO as porogens, and then obtained by removing 1 cm wall from one end of the fused silica capillary tube. The fiber has large surface area (536 m2 g−1), pore capacity (0.694 cm3 g−1) good thermal stability (up to 320 ℃), long service life and good reproducibility (RSD ＜5% throughout 110 times) which facilitated for high throughput headspace solid phase microextraction (HS-SPME) coupled to gas chromatograph (GC) analysis. The HS-SPME/GC method using the new fiber was evaluated by the determination of five organophosphate esters (OPEs) in soil samples coupled to flame photometric detector (FPD). The proposed HS-SPME-GC/FPD method yielded satisfactory limits of quantification (0.03 ng g−1∼0.24 ng g−1); linearity (≥0.99), good intra- and inter-day precision expressed as relative standard deviations for a single fiber were in the range of 5.2–9.0% and 4.8–9.0%, respectively, and fiber-to-fiber reproducibility was in the range of 5.9–9.7%. The method was applied for the analysis of OPEs in environmental soil samples and the relative recoveries were found to be in the range from 80.1 to 105.6%. Based on these features, the new fiber has great potential for widespread use as a high throughput trace analysis tool. [ABSTRACT FROM AUTHOR]

The results of remote detection of objects containing explosives with a lidar detector of traces of explosives in combination with a portable express gas chromatograph are presented. It is shown that the lidar detector of traces of explosives confidently detects the simulators of TNT, hexogen, and PETN from a distance of 5 m when sounding the surface of a sample. Laser action on the sample surface causes desorption of vapors, which are reliably detected by the gas chromatograph. It is shown that the joint use of the laser sounding and gas chromatography techniques makes it possible to increase the reliability of detection of explosives. The prospects of using the gas chromatography in the development of laser sounding techniques are determined. [ABSTRACT FROM AUTHOR]