Micro gas chromatograph

Micro gas chromatography (μGC) using microfabricated silicon columns has been developed in response to the requirement for portable on-site gas analysis. Although different stationary phases have been developed, repeatable and reliable surface coatings in these rather small microcolumns remains a challenge. Herein, a new stationary phase coating strategy using magnetic beads (MBs) as carriers for micro column is presented. MBs modified with organopolysiloxane (MBs@OV-1) and a metal organic framework (MBs@HKUST-1) are deposited in on-chip microcolumns assisted with a magnetic field with an optimized modification process...

Plant-induced resistance can be an important component of soybean mites biological control programs. This work evaluates the preference of predatory mite Neoseiulus californicus (Acari: Phytoseiidae) to soybean plants under single and multiple herbivory conditions by two-spotted spider mite Tetranychus urticae (Acari: Tetranychidae), and velvetbean caterpillar Anticarsia gemmatalis (Lepidoptera: Noctuidae). Using a Y olfactometer, the following scenarios were evaluated: soybean with no infestation and soybean infested with A...

The presence of Emerging Pollutants (EPs) on the beaches of Acapulco, Mexico, is evaluated for the first time. Samples were taken from the discharge of the wastewater treatment plant at Olvidada beach, and at three beaches that receive contributions from different streams that cross through the city in Santa Lucia Bay (SLB). Using solid phase extraction and gas chromatography/mass spectrometry, 77 EPs were identified. A semiquantitative evaluation of their concentrations were made using the relative areas of the chromatographic peaks, showing that the contamination of the beaches of SLB is mainly due to the pollutants going into the streams of the micro-basins...

Terpenes and terpenoids are the principal responsible for the aroma of Cannabis, playing an important role in the interaction with the environment. Analytical determination of these compounds can be done by headspace coupled to solid phase micro-extraction (HS-SPME) and then injected in a gas chromatograph. In the present study, we determined distribution constants between gas and polydimetylsiloxane (PDMS), a conventional SPME liquid phase, at three temperatures between 303.15 and 343.15 K for major Cannabis terpenes and terpenoids employing a method based in gas chromatography using four capillary columns for monoterpenes and five columns for sesquiterpenes...

Mandarin production has increased in recent years, especially for fresh consumption, due to its ease of peeling, its aroma, and its content of bioactive compounds. In this sense, aromas play a fundamental role in the sensory quality of this fruit. The selection of the appropriate rootstock is crucial for the success of the crop and its quality. Therefore, the objective of this study was to identify the influence of 9 rootstocks ("Carrizo citrange", "Swingle citrumelo CPB 4475", "Macrophylla", "Volkameriana", "Forner-Alcaide 5", "Forner-Alcaide V17", "C-35", "Forner-Alcaide 418", and "Forner-Alcaide 517") on the volatile composition of "Clemenules" mandarin...

For the first time, a comprehensive analytical method based on a one-dimensional metal-organic framework comprising "quick, easy, cheap, effective, rugged, and safe-dispersive micro solid phase extraction-dispersive liquid-liquid microextraction" was introduced in this research. Moreover, the first-ever attempt was accomplished to apply the iron-gallic acid metal-organic framework in analytical method development. The goal of the research was to analyze the pesticide content of watermelon comprehensively in its flesh and juice...

A polypyrrole (PPy)-cotton pad sorbent enclosed in tea bag envelope was developed and used in micro-solid phase extraction (µ-SPE) for the determination of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). After extraction, the extract was qualified and quantified by a gas chromatograph equipped with a flame ionization detector (GC-FID). Parameters influencing this developed method and the efficiency of µ-SPE were studied and optimized. Under the optimal conditions, the developed method provided good linearity in a concentration range of 0...

The purpose of this study was to reveal the relationship between core microorganisms and flavor substances in the fermentation process of corn wine. Microbial diversity, volatile and non-volatile flavor substances were detected by high-throughput sequencing (HTS), headspace solid phase micro-extraction gas chromatography-mass spectrometry (HS-SPME/GC-MS) and gas chromatography time of flight mass spectrometry (GC-TOF-MS). High performance liquid chromatography (HPLC) was used to detect organic acids in corn wine fermentation, and its physiochemical properties were tracked...

RATIONALE: Volatile organic compounds (VOCs) emitted by an artificial leather part for car interiors are determined with GC-MS (gas chromatograph coupled to a mass spectrometer) using simultaneous electron and chemical ionization (EI&CI). A device for swift reagent ion switching in CI mode between consecutive runs is presented. METHODS: VOCs emitted from the investigated material were sampled onto Tenax® absorption tubes using micro emission chambers and subsequently injected into the GC through thermal desorption...

For the first time, this survey demonstrates the use of MIL-53 (Cu) in an analytical method for the detection and determination of some pesticides through their extraction and preconcentration from red and yellow watermelon juices. The other predominance of the research is using a green metal-organic framework that is based on copper and synthesized in deionized water. After conducting the synthesis process, Fourier transform infrared spectrophotometry, X-ray diffraction, scanning electron microscopy, and nitrogen adsorption/desorption analyses were carried out...

Common bunt disease of wheat in China is caused mainly by Tilletia foetida . However, reliable approaches for determining disease-associated biochemical markers are rarely reported. Here, a headspace-solid-phase microextraction coupled with headspace GC-tandem mass spectrometry (HS-SPME-GC-MS) was used to screen volatile substances in infected wheat, and an optimal chemical marker was selected to establish analytical methods for disease determination. Non-targeted screening of 13 volatile compounds unique to diseased wheat allowed a metabolite with rotten fish-like smell, trimethylamine (TMA), to be selected as the inspection marker...

Mobility is a key feature affecting the environmental fate, which is of particular importance in the case of persistent organic pollutants (POPs) and emerging pollutants (EPs). In this study, the global mobility classification artificial neural networks-based models employing GC retention times (RT) and 2D molecular descriptors were constructed and validated. The high usability of RT was confirmed based on the feature selection step performed using the multivariate adaptive regression splines (MARS) tool. Although RT was found to be the most important, according to Kruskal-Wallis ANOVA analysis, it is insufficient to build a robust model, which justifies the need to expand the input layer with 2D descriptors...

A comparison was performed on various methods detecting the volatile contaminants (VCs) in recycled poly(ethylene terephthalate) (rPET) flakes, the results demonstrated that head-space solid phase micro-extraction combined with comprehensive two-dimensional gas chromatograph-tandem quadrupole-time-of-flight mass spectrometry (HS-SPME-GC×GC-QTOF-MS) was a sensitive, effective, accurate method, and successfully applied to analyze 57 rPET flakes collected from different recycling plants in China. A total of 212 VCs were tentatively identified, and the possible source were associated with plastic, food, and cosmetics...

The QuEChERSER mega-method has recently been introduced to quantify and identify a wide range of chemical residues (pesticides, veterinary drugs, environmental contaminants, among others) in nearly all types of foods. The approach calls for taking a small amount of the initial extract to cover analytes amenable to liquid chromatography, and the remainder is salted out for analysis by gas chromatography (GC), both with mass spectrometry (MS) based detection. In the case of GC-MS(/MS), the extract undergoes automated robotic mini-cartridge solid-phase extraction (SPE) cleanup in a technique known as µSPE or instrument-top sample preparation (ITSP)...

The present research is focused on the optimization of an automatized sample preparation and fast gas chromatography-mass spectrometry (GC-MS) method for the analysis of fatty acid methyl esters (FAMEs) in blood samples and dietary supplements, with the primary objective being a significant reduction of the analysis time and, hence, an enhanced sample throughput. The mass spectrometer was operated in the scan/selected ion monitoring (SIM) acquisition method, thus enabling the obtainment of qualitative and (highly sensitive) quantitative data...

Heritage guidelines recognize odors as a value associated with a place. This study aims to clarify the connection between heritage and volatile organic compounds at the molecular level. At variance with previous studies, usually focused only on book-related compounds from accelerated degradation tests, the whole air of one of the most significant historical libraries in Italy was studied. A sampling of the volatiles off-gassing from the two most iconic rooms, respectively open and forbidden to visitors, was performed via a non-invasive, nondestructive green method, solid-phase-micro-extraction...

Carbon nanotube (CNT)-based chemiresistors are promising gas detectors for gas chromatography (GC) due to their intrinsic nanoscale porosity and excellent electrical conductivity. However, fabrication reproducibility, long desorption time, limited sensitivity, and low dynamic range limit their usage in real applications. This paper reports a novel on-chip monolithic integrated multimode CNT sensor, where a micro-electro-mechanical system-based bulk acoustic wave (BAW) resonator is embedded underneath a CNT chemiresistor...

In this paper, a micro gas chromatographic column (μGCC) was fabricated via the layer-by-layer (LBL) deposition of mesoporous silica (MS) as the stationary phase. The μGCC with embedded elliptical-cylindrical posts was fabricated by typical micro-electro-mechanical system (MEMS) techniques. The MS powder was prepared by a sol-gel method and then deposited inside the microchannels of the μGCC by LBL deposition. This process avoided the high temperature required for the sol-gel method to directly prepare MS inside the microchannel surfaces of the μGCC...

This paper would like to show all the data related to an intensive field campaign focused on the characterization of the Polyaromatic Hydrocarbons (PAHs) composition profile in almost 60 honey samples collected in Central Italy. The analytical data here reported are the base for a study aimed to identify the pollution sources in a region. 22 PAHs were analyzed by means of ultrasound-vortex-assisted dispersive liquid-liquid micro-extraction (DLLME) procedure followed by a triple quadrupole gas chromatograph/mass spectrometer (GC-MS)...

In order to reveal the pollution characteristics and risk levels of DBPs in typical drinking water sources in Wuhan under the COVID-19 pandemic, 26 sampling sites were selected in typical drinking water sources in Wuhan. N,N -diethyl-1,4-phenylenediamine spectrophotometry and gas chromatograph-micro-cell electron capture detector (GC-μECD) methods were used to detect residual chlorine disinfectants and DBPs in water, respectively, and their health and ecology risks were assessed. The results showed that free chlorine or total residual chlorine were detected in 16 of the 26 water samples, and the maximum concentration was 0...