Micro-gas chromatograph

The species distribution within a PEM fuel cell is critical to fully characterize the local performance and accurately quantify the various modes of water transport. The most commonly used analytic technique for measuring the gas composition within a fuel cell is gas chromatography (GC). Mench et al.13 demonstrated the measurement of water vapor, hydrogen, and oxygen concentration distributions at steady state. A micro gas chromatograph was utilized to measure the samples, which were extracted from eight... 

Gaz De France provided natural gas. It is composed of 92.2% of methane. The other components analysed with the micro-gas chromatograph are CO2, N2, C2H6, C4HX. /-C4H10, W-C4H10, 72-C5H42 and (Table 2). 

A micro gas chromatograph, as small as a check card (dimensions 91 x 59 x 27 mm), was presented by SLS MICRO TECHNOLOGY GmbH [122], This device is one of the first commercial products of micro system technology and it possesses sufficient robustness to withstand chemical and thermal stress. Hence, it should be ideal for inline measurements in a plant. 

Figure4.73 GCM 5000 micro gas chromatograph on an integrated circuit board [122] (by courtesy of SLS MICRO TECHNOLOGY GmbH).

Microfluidic concepts can be used to develop an integrated total chemical analysis system (TAS) [40], which include sample preparation, separation, and detection. The microminiaturization of a TAS onto a monolithic structure produces a //-TAS that resembles a small sensor. The first /(-TAS was a micro-gas chromatograph (GC) fabricated on a 5-in. silicon wafer in 1979 by a group at Stanford University [41]. Since then, developments in micromachining has led to the development of microsensors, microreactors,... 

Catalytic reactions were carried out using a micro fixed bed flow type reactor. 60 to 400 mg of oxidized diamond-supported catalyst was used. The effluent was analyzed by an on-line micro gas chromatograph. 

Reaction products were analyzed using several chromatographs. Gas products were analyzed using a Flewlett-Packard Quad-Series Refinery Gas Analyzer Micro Gas Chromatograph (QRGA). The analysis of the aqueous phase collected beyond the reactor used a Hewlett-Packard 5790 GC with a thermal conductivity detector and a Porapak Q column. Oil and wax were combined and analyzed with a Hewlett-Packard 5890 GC with a flame ionization detector and a 60 m DB-5 column. The reactor wax was analyzed on a Hewlett-Packard 5890 High Temperature GC with an flame ionization detector and a 30 m alumina clad HT-5 column. 

Historically, high-quality gas analyses in fuels required sophisticated laboratory instrumentation. However, fast, portable, micro-gas chromatographs... 

R. Sacks, Development of a High-Performance Autonomous Micro Gas Chromatograph, 25th Int. Symp. Capillary Chromatography, Riva del Garda, Italy, May 2002, paper PL.ll. 

Principles and Characteristics As mentioned already (Section 3.5.2) solid-phase microextraction involves the use of a micro-fibre which is exposed to the analyte(s) for a prespecified time. GC-MS is an ideal detector after SPME extraction/injection for both qualitative and quantitative analysis. For SPME-GC analysis, the fibre is forced into the chromatography capillary injector, where the entire extraction is desorbed. A high linear flow-rate of the carrier gas along the fibre is essential to ensure complete desorption of the analytes. Because no solvent is injected, and the analytes are rapidly desorbed on to the column, minimum detection limits are improved and resolution is maintained. Online coupling of conventional fibre-based SPME coupled with GC is now becoming routine. Automated SPME takes the sample directly from bottle to gas chromatograph. Split/splitless, on-column and PTV injection are compatible with SPME. SPME can also be used very effectively for sample introduction to fast GC systems, provided that a dedicated injector is used for this purpose [69,70],... 

Nishikawa, I. and T. Hayakawa. 1986. Bromination and gas chromatographic determination of micro amounts of acrolein in rain water. Jour. Chromatog. 551 566-570. 

The volatile substances were extracted from portions of 0. lg hair using solid-phase micro extraction (SPME). The method uses a fibre coated with an adsorbent that can extract organic compounds from the headspace above the sample. Extracted compounds are desorbed upon exposure of the SPME fibre in the heated injector port of a gas chromatograph (GC). 

Figure 14.3 shows a typical capillary gas chromatograph with the major components labeled. This gas chromatograph set up includes compressed gas tanks for the carrier gas (mobile phase) and any necessary detector gases, an auto-injector that employs a micro-syringe for delivering the necessary small sample volumes and an inlet capable of the... 

G.A. Eiceman, E.G. Nazarov, R.A. Miller, E.V. Krylov and A.M. Zapata, Micro-machined planar field asymmetric ion mobility spectrometer as a gas chromatographic detector, Analyst 127(4) (2002) 466-471. 

The majority of the many methods used to study the composition of equilibrium solutions of carbohydrates examine the mixture without separating the individual components. With the discovery that the anomeric forms of sugars could be readily separated by gas chromatography of their tri-methylsilyl ethers, a new approach to the problem was found. A protocol was developed for the direct gas chromatographic analysis of the amount of each anomer present in an aqueous solution. The protocol can be used on the micro scale and can be used in enzyme assays such as that for mutarotase. The method has been made more effective by combining gas chromatography with mass spectrometry. It is shown how mass spectral intensity ratios can be used to discriminate anomers one from another. The application of these methods to the study of complex mutarotations is discussed. 

The authors applied this concept to both gas/liquid (see Figure 3.75) and liquid/ liquid systems (see Figure 3.76). This set-up consisted in the core of a tubular reactor with an interdigital micro mixer as dispersion unit (compare Figure 3.77). The peripheral equipment consisted of an automated pipetting robot, a fraction collector and a gas-chromatograph equipped with an automatic injector. 

Lehmann, U., Krusemark, O., Muller, J., Micro machined gas chromatograph based on a plasma polymerised stationary phase. Micro Total Analysis Systems, Proceedings of the 4th pTAS Symposium, Enschede, Netherlands, May 14-18, 2000, 167-170. 

Hannoe, S., Sugimoto, I., Katoh, T., Silicon-micromachined separation columns coated with amino acid films for an integrated on-chip gas chromatograph. Micro Total Analysis Systems 98, Proceedings pTAS 98 Workshop, Banff, Canada, 13-16 Oct. 1998, 145-148. 

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