Gas chromatography-thermal energy

For the analyses discussed here, we have used Gas Chromatography-Thermal Energy Analysis (GC-TEA ) and/or High Pressure Liquid Chromatography-Thermal Energy Analysis (HPLC-TEA). The TEA has been used as the detector... 

Table 2. Applications of gas chromatography-thermal energy analyser (GC-TEA) to explosive analysis...

Billedeau SM, Thonpson HC Jr, Miller BJ, et al. 1986. Volatile N-nitrosamines in infant pacifiers sold in the United States as determined by gas chromatography/thermal energy analysis. J Assoc Off Anal Chem 69 31-... 

Mola, M., G. Lionetti, and A. Nunziata Determination of tobacco specific nitrosamines in mainstream smoke by gas chromatography-thermal energy analysis 57th Tobacco Science Research Conference, Program Booklet and Abstracts, Vol. 57, Paper No. 10, 2003, p. 23. 

Theiler, R., K. Sato, T. Aspelund, and A. Miller Inhibition of A-nitrosamine formation in a cured ground pork belly model system J. Food Sci. 49 (1984) 341-344. Thompson, H.C. Jr, S.M. BUledeau, B.J. Miller, E.B. Hansen Jr, J.P. Freeman, and M.L. Wind Determination of A-nitrosamines and A-nitrosamine precursors in rubber nipples from baby pacifiers by gas chromatography thermal energy analysis J. Toxicol. Env. Hlth. 13 (1984) 615-632. 

NPYR, N-nitrosopyrrolidine NPRO, N-nitrosoproline NTHZ, N-nitroso-thiazolidine NPIP, N-nitrosopiperidine NDEA, N-nitrosodiethyl-amine GC-TEA, gas chromatography - thermal energy analyzer NMOR, N-nitrosomorpholine NDPA, N-nitrosodipropylamine. 

Supercritical fluid chromatography-thermal energy analyser Supercritical fluids are produced by heating a gas above its critical temperature or compressing a liquid above its critical pressure. In SFC, the sample is carried through a separating column by a supercritical fluid (typically C02) that is used as mobile... 

VL medium, pH 6 4, with or without cells was incubated in sealed tubes for 10 hrs at 37 C NDMA was determined by gas chromatography with the Thermal Energy Analyzer as a detector (Thermo Electron Corp, Waltham, MA). The identity of NDMA was confirmed by 6C mass spectrometry. 

The data in Table I are also significant in terms of the type of analysis to determine the presence of NDMA. In all cases analysis was done using gas chromatography coupled with a Thermal Energy Analyzer, a sensitive, relatively specific nitrosamine detector (12). Further, in six of the studies, the presence of NDMA in several samples was confirmed by gas chromatography-mass spectrometry (GC-MS). The mass spectral data firmly established the presence of NDMA in the beer samples. 

Reliable analytical methods are available for determination of many volatile nitrosamines at concentrations of 0.1 to 10 ppb in a variety of environmental and biological samples. Most methods employ distillation, extraction, an optional cleanup step, concentration, and final separation by gas chromatography (GC). Use of the highly specific Thermal Energy Analyzer (TEA) as a GC detector affords simplification of sample handling and cleanup without sacrifice of selectivity or sensitivity. Mass spectrometry (MS) is usually employed to confirm the identity of nitrosamines. Utilization of the mass spectrometer s capability to provide quantitative data affords additional confirmatory evidence and quantitative confirmation should be a required criterion of environmental sample analysis. Artifactual formation of nitrosamines continues to be a problem, especially at low levels (0.1 to 1 ppb), and precautions must be taken, such as addition of sulfamic acid or other nitrosation inhibitors. The efficacy of measures for prevention of artifactual nitrosamine formation should be evaluated in each type of sample examined. 

Gas chromatography is one of the most powerful analytical techniques available for chemical analysis. Commercially available chemiluminescence detectors for GC include the FPD, the SCD, the thermal energy analysis (TEA) detector, and nitrogen-selective detectors. Highly sensitive detectors based on chemiluminescent reactions with F2 and active nitrogen also have been developed. 

The majority of the analytical methods for detection of N-nitroso compounds have employed gas chromatography (GC) or liquid chromatography (LC) in conjunction with a thermal energy analyzer (TEA) [20], which relies on the pyrolytic breakdown of N-NO moieties to release the nitrosyl radical. Despite the isolation techniques used, the quantitative determination of N-nitroso compounds requires a concomitant posi-... 

J.M.P. Douse, Trace analysis of explosives at the low nanogram level in handswab extracts using columns of Amberlite XAD-7 porous polymer beads and sdica capillary column gas chromatography with thermal energy analysis and electron capture detection , J. Chromatogr., 328 (1985) 155-165. 

Electron impact (El) ionization is one of the most classic ionization techniques used in mass spectrometry. A glowing filament produces electrons, which are then accelerated to an energy of 70 eV. The sample is vaporized into the vacuum where gas phase molecules are bombarded with electrons. One or more electrons are removed from the molecules to form odd electron ions (M+ ) or multiply charged ions. Solids, liquids and gases can be analyzed by El, if they endure vaporization without decomposition. Therefore the range of compounds which can be analyzed by El is somewhat limited to thermally stable and volatile compounds. The coupling with gas chromatography has been well established for... 

D. H. Fine and D. P. Rounbehler, Trace analysis of volatile N-nitroso compounds by combined gas chromatography and thermal energy analysis. Journal of Chromatography, 1975,109(2), 271-279. 

The prototype of the tobacco specific nitrosamines, NNN, has been detected in both tobacco smoke and unburned tobacco. Various analytical methods have been used including gas chromatography (GLC) (13,14,15,16) combined GLC-mass spectrometry (17), thin layer chromatography (18) high pressure liquid chromatography (HPLC) (19,20), and combined HPLC-thermal energy analysis (21). 

V-Nitrosodiethanolamine can be determined in air and bulk process samples. Air samples are collected on glass fibre filters, extracted with 2-propanol and analysed by gas chromatography with thermal energy analyser detection. The limit of detection is 200 ng per sample (0.42 pg/m ). Bulk samples can be screened for 7V-nitrosodiethanol-amine by high-performance liquid chromatography (HPLC) with ultraviolet detection (Occupational Safety and Health Administration, 1990). 

Fig. 3. Processing scheme. Reprinted with permission from Warren et al. [46]. Copyright (1999) Forensic Science Society. CE, capillary electrophoresis GC, gas chromatography TEA, thermal energy analyser IC,...

J. M. F. Douse, Dynamic Headspace Method for the Improved Clean-up of Gunshot Residues prior to the Detection of Nitroglycerine by Capillary Column Gas Chromatography with Thermal Energy Analysis Detection, Journal of Chromatography 464 (1989) 178. 

ECD = electron capture detection ED = electrochemical detection HPLC = high-performance liquid chromatography HRGC = high resolution gas chromatography in] = injection NR = not reported PMDE = pendant mercury drop electrode -TEA = thermal energy analyzer TLC = thin-layer chromatography... 

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