Portable GCs

Headspace analysis has also been used to determine trichloroethylene in water samples. High accuracy and excellent precision were reported when GC/ECD was used to analyze headspace gases over water (Dietz and Singley 1979). Direct injection of water into a portable GC suitable for field use employed an ultraviolet detector (Motwani et al. 1986). While detection was comparable to the more common methods (low ppb), recovery was very low. Solid waste leachates from sanitary landfills have been analyzed for trichloroethylene and other volatile organic compounds (Schultz and Kjeldsen 1986). Detection limits for the procedure, which involves extraction with pentane followed by GC/MS analysis, are in the low-ppb and low-ppm ranges for concentrated and unconcentrated samples, respectively. Accuracy and precision data were not reported. 

The number of pollutants that are currently regulated constitute only a fraction of those found in the environment. In addition, their chemical characteristics and concentrations may vary widely. New and alternative methodologies that are simple, rapid, and reliable need to be developed. Enzyme immunoassay and portable GC and IR techniques need greater attention. 

The OPCW mobile laboratory includes a portable GC/MS. The system shown in Picture 5 including printer and helium connection kit is packed in five transport boxes. Because of the modular design of the instrument, it is shipped with two GC-ovens and two GC-injectors in order to allow the... 

Bruker EM 640S portable GC/MS on-site analysis Bruker EM 640S GC/MS testing and preparation of instruments for on-site analysis Bruker EM 640S portable GC/MS packing procedures... 

Bruker EM 640S portable GC/MS installation and handling of software... 

The analytical instrument currendy used in the OPCW mobile laboratory is the portable GC/MS Bruker EM 640S. The instrument and supplementary equipment are packed in 5 transport boxes. (The instrument and procedures for use are described in Chapter 2 and Chapter 4) Before being issued for an inspection, the instrument is validated for on-site use at the OPCW Laboratory following... 

Bruker EM 640S Portable GC/MS with AMDIS Data Analysis Software (Blinded Mode) for Qualitative Analysis of Liquid Samples Prepared by On-site Methods... 

Bruker EM 640S Portable GC/MS Installation and Handling of Software... 

In 1996, an international team of experts evaluated the only two available portable GC/MS systems at this time Viking SpectraTrak 672 (USA) and Bruker EM 640S (Germany). As the Viking SpectraTrak 672 instrument did not fulfill requirements concerning the possibility of being operated in blinded mode, only Bruker 640S passed successfully a series of tests, and was approved by OPCW for on-site analysis and became an item of approved inspection equipment. 

Standard Operating Procedure (SOP) SOP-LAB-EQP-005, Bruker EM640S Portable GC/MS with AMDIS Data Analysis Software (Blinded Mode) for Qualitative Analyses of Liquid Samples Prepared by On-site Methods, Version 3, The Technical Secretariat of the Organization for the Prohibition of Chemical Weapons, The Hague, 1999. 

In the last five years, the OCAD has grown at a steady pace as shown in Figures 4 and 5. In particular, the MS and GC(RI) data have increased at a steady rate and are expected to continue in this way. The NMR and IR data, on the other hand, have not been growing at the same rate as the MS and GC(RI), and appear to be leveling off. The main reason for this is that the Secretariat has to date been focusing on MS and GC(RI) data for its portable GC/MS inspection equipment. A second equally important factor may be that the MS and GC(RI) data have been obtained by quick microsynthesis often producing mixtures of chemicals, while recording of NMR data would require rather pure compound, and therefore, need additional cleanup procedures. 

The technology of GC-MS can be downsized for field usage and is now commercially available. Inficon (USA) manufactures a field-portable GC-MS, Hapsite. Vapor is withdrawn for 30 s into the Tenax preconcentration system, thermally desorbed into the apolar capillary colmnn with elevated temperature control, and the separated components are finally analyzed by the electron ionization quadrupole mass spectrometer. GB, GD, GA, and HD are detected and identified within 12 min with postulated LOD values of 0.2, 0.5, 8, and 0.3 pg/m (Sekiguchi et al, 2006). Gaseous and weakly volatile (boiling temperature >250°C) CWAs cannot be detected. 

Henry, C. (1997). Taking the show on the road portable GC and GC/MS. Anal. Chem. 69 195A-201A. 

The concentrations of the contaminants in water immediately prior to and following treatment must be determined to allow analysis of the efficiency of the system. Pilot-study programs designed to determine the effects of varying system parameters are based on reliable water-quality analyses. Where rapid reporting of sampling results is a benefit, the portable GC instrument has found application. 

The continued concern over various residues and additives lead to more efficient and rapid testing methods. Conventional chromatographic testing will be replaced by a 2-tiered approach involving rapid on the spot screening (bio-sensor, immunoassay or portable GC) followed by confirmation by conventional methods. More selective detectors such as mass spectrometry (MS), tandem MS-MS and Fourier Transform infra-red wiU be used and sample preparation will be improved by using SPE, new extraction technologies, and laboratory robotics [36]. 

There are small portable GCs available from a number of manufacturers. There are limited applications, with isothermal ovens, but they perform well for specific applications. [See C. Henry, Taking the Show on the Road. Portable GC and GC/MS (Product Review), Anal. Chem., 69(5) (1997) 195A]. 

Since both GC and MS instruments have been appreciably reduced in size, the natural next step was the development of portable GC-MS equipment. An example of a commercially available GC-MS system is the Hapsite, from Inficon, which is a compact quadrupole GC-MS designed specifically for the analysis of VOCs. The Hapsite weighs only 16.8 kg... 

The Model 4300 zNose is a portable GC that can detect and measure levels of many types of vapours, toxins, explosives, narcotics and other compounds. It is the first GC to be based on surface acoustic wave (SAW) technology. The battery pack allows field operation for six hours. Analysis time is between 1-60 seconds and sensitivity is low ppb for most compounds with a precision of 5 % RSD. The combined weight of the sampler, chassis and charger is 14.6 kg. 

Field portable GC instruments most often do not have the capability of temperature programming because of the limited amount of power available. In such instruments the separation... 

Miller and co-workers show an on-stream sampler and a portable GC system to analyze stack gases as part of the requirements of determination of particulate matter from incinerator stacks. The concentrations of carbon dioxide, oxygen, and carbon monoxide are measured and that of nitrogen is calculated by difference. This method is of higher precision and can save time and labor when compared with the Orsat analyzer method. Further, this GC system is portable and all the components are mounted on a 2 ft by 3 ft laboratory cart, which makes mobile measurements possible. A summary of some of the techniques used is presented in Table 6.2. 

Air is injected directly into a portable GC equipped with a PID. 

Air analysis for benzene may be performed by NIOSH Methods 3700,1500,1501 (NIOSH 1984). An air bag (Tedlar bag) is filled to about 80% capacity at a flow rate of 20 to 50 mL/min. The air is injected within 4 hours after collection into a portable GC equipped with a photoionization detector. Alternatively, the air is passed over coconut shell charcoal the adsorbed benzene is desorbed into CS2 and injected into GC-FID,... 

Portable GC/MS systems Spectra Trak and CADIS Mass-Spec-On-Chip (MSOC)... 

Efforts to assist search-and-rescue teams in locating people buried under collapsed structures by using handheld IMS instruments have been proposed. One study focused on detection of VOCs anitted in expired air of fasting monks in Greece, with the objective to simulate the breath exhaled by people who could be trapped under collapsed buildings in an event such as an earthquake indeed, a 30-fold increase in acetone level was found using a portable GC-IMS. In another study, the objective was to detect vapors emanating from human urine, mainly acetone, to indicate the presence of people under debris. ... 

The example of solvent concentration measurement and the accompanying results of drying rate calculation are shown in Table 7.3.2., and the accompanying specification of dryer and the formulation of coating solution is given in Table 7.3.3 and 7.3.4. The solvent concentrations at the exhaust duct are measured by gas chromatography(MTl Analytical Instrument 200, Portable GC). The solvent concentrations were measured three times at the same point, and the deviations from flie average value were less flian 5%. 

Portable GCs GC and GC-MS remain dominant techniques for the determination of multiple volatile and semivolatile organic compounds in workplace air analysis. Portable gas chromatographs were introduced in the late 1970s and the technology has continued to evolve ever since. Most field GCs consist of an injection system with either syringe... 

The Photovac Voyager, a fifth-generation portable GC, is shown in Figure 2. Features of the Photovac Voyager include a three-column system and dual PID-ECD detectors. The Voyager also includes a factory-programmed assay that provides preset instrument operating parameters and compoimd library to simplify operation. 

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