scholarly journals A Microvalve Module with High Chemical Inertness and Embedded Flow Heating for Microscale Gas Chromatography

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 632
Author(s):  
Hsueh-Tsung Lu ◽  
Yutao Qin ◽  
Yogesh Gianchandani
Keyword(s):  
Gas Chromatography ◽  
Aromatic Hydrocarbons ◽  
Fused Silica ◽  
High Chemical ◽  
Chemical Inertness ◽  
Volatile Organic ◽  
Measured Ratio ◽  
Chromatographic Peaks ◽  
Lithographic Masks ◽  
Small Form Factor

This paper reports a multi-valve module with high chemical inertness and embedded flow heating for microscale gas chromatography (µGC) systems. The multi-valve module incorporates a monolithically microfabricated die stack, polyimide valve membranes, and solenoid actuators. The design incorporates three valves within a single module of volume 30.2 cm3, which is suitable for the small form factor of µGC systems. The die stack uses fused silica wafers and polyimide valve membranes that enhance chemical inertness. The monolithic die stack requires only three lithographic masks to pattern fluidic microchannels, valve seats, and thin-film metal heaters and thermistors. The performance of fabricated multi-valve modules is compared to a commercial valve in tests using multiple volatile organic compounds, including alkanes, alcohols, ketones, aromatic hydrocarbons, and phosphonates. The valves show almost no distortion of chromatographic peaks. The experimentally measured ratio of flow conductance is 3.46 × 103, with 4.15 sccm/kPa in the open state and 0.0012 sccm/kPa in the closed state. The response time is <120 ms.

scholarly journals Reversed Phase SPE and GC-MS Study of Polycyclic Aromatic Hydrocarbons in Water Samples from the River Buriganga, Bangladesh

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Md. Saddam Nawaz ◽  
Farhana Khanam Ferdousi ◽  
Mohammad Arifur Rahman ◽  
A. M. Shafiqul Alam
Keyword(s):  
Gas Chromatography ◽  
Polycyclic Aromatic Hydrocarbons ◽  
River Water ◽  
Flow Rate ◽  
Aromatic Hydrocarbons ◽  
Water Samples ◽  
Research Work ◽  
Reversed Phase ◽  
Fused Silica ◽  
Polycyclic Aromatic

Polycyclic aromatic hydrocarbons (PAHs) are semivolatile organic compounds (SVOCs) categorized as persistent organic pollutants (POPs). PAHs are ubiquitous in terrestrial, atmospheric, and particularly aquatic environments throughout the world and have been detected in lakes, ground waters, and rivers. This research work involved the analysis of five PAHs, anthracene, fluorene, naphthalene, phenanthrene, and pyrene, in water sample collected from the river Buriganga, Bangladesh. The extraction of water samples was carried out by reversed phase solid-phase extraction (RP-SPE) technique with C-18 SPE cartridges. A solvent mixture of dichloromethane and hexane (1 : 2) with a flow rate of 0.5 mL/min was used as eluent. Percentage recoveries of five PAHs for this technique were in the range of 81.47 ± 1.16 to 98.60 ± 0.61%. PAHs quantification was achieved by using an ion trap gas chromatography mass spectrometer (GC-MS) interfaced to gas chromatography (GC) equipped with a fused silica capillary column. Helium was used as carrier gas with a flow rate of 1.0 mL/min. The commonly detected PAH compounds in the river water were anthracene, naphthalene, and phenanthrene at the concentration ranges of 0.451 to 3.201, 0.033 to 3.1131, and 0.320 to 2.546 μg/mL, respectively. The results reflect that PAHs presented in this river water were mostly from petrogenic and pyrogenic sources.

scholarly journals Characteristics of VOCs Released from Plywood in Airtight Environments

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 709 ◽  
Author(s):  
Tianyu Cao ◽  
Jun Shen ◽  
Qifan Wang ◽  
Huifang Li ◽  
Cong Xu ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Polyvinyl Chloride ◽  
Mass Spectrometer ◽  
Aromatic Hydrocarbons ◽  
Emission Characteristics ◽  
Characteristic Curves ◽  
Volatile Organic ◽  
Water Based

In order to explore the emission characteristics of volatile organic compounds (VOCs) and different VOC components in airtight environments, polyvinyl chloride laminated plywood (PVC-P), melamine-impregnated paper laminated plywood (MI-P), water-based paint laminated plywood (WP-P) and unfinished plywood (UF-P) were tested as materials in 15 L small environment cabins. VOCs were collected after being sealed for 2 h, 4 h, 6 h, 8 h, 12 h, 18 h, 24 h and 30 h under different loading ratios (1 m2/m3, 1.5 m2/m3, 2 m2/m3, 2.5 m2/m3) and analyzed using a gas chromatography–mass spectrometer. The results show that VOCs gradually increased and tended to be saturated with the increase of time in an airtight environment. The saturation of veneered plywood was faster than unfinished plywood and the pollution degree of three kinds of veneered plywood from lowest to highest was in order of PVC-P, MI-P, WP-P. Aromatic hydrocarbons account for more than half of VOC concentration, and was most obviously affected by the loading ratios. Surfaced laminated plywood can reduce the emission of aromatic hydrocarbons, but also increases the amount of other compounds released. The concentration of VOC-components shows different characteristic curves at different loading ratios due to the influence of decorative materials.

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