Head-space gas chromatography

This GC-based monitoring technique circumvents the lack of robustness of the latex GC technique by analyzing the reactor head-space [135, 136]. However, the estimation of the monomer concentrations in the polymer particles requires that equilibrium between the latex and gas phase is attained. In addition, the values of the equilibrium parameters are required, which introduces an additional uncertainty to the measurements. Note also that formulation ingredients such as CTAs are not measurable by this means. 

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Residual monomers in SAN have been a growing environmental concern and can be determined by a variety of methods. Monomer analysis can be achieved by polymer solution or directly from SAN emulsions (27) followed by "head space" gas chromatography (gc) (28,29). Liquid chromatography (Ic) is also effective (30). 

Determination of chloroform in colchicine by head-space gas chromatography... 

DETERMINATION OF CHLOROFORM IN COLCHICINE BY HEAD-SPACE GAS CHROMATOGRAPHY... 

Head-space gas chromatography is an analytical device specifically suitable for the separation and simultaneous determination of volatile constituents present in solid or in liquid samples. 

Principle The underlying principle of head space gas chromatography is the analysis of the vapour phase in equilibrium with the solid or liquid phase. 

Yamano Y, Ito I, Nagao N, et al. 1987. [A simple determination method of bromide ion in plasma of methyl bromide workers by head space gas chromatography.] Sangyo Igaku 29 196-201. (Japanese)... 

Golderman L, Gellert J, Teschke R. 1983. Methods and Devices. Quantitative assessment of carbon tatrachloride levels in human blood by head-space gas chromatography application in a case of suicidal carbon tetrachloride intoxication. Intensive Care Medicine 9 131-135. 

Selected methods for the analysis of ethylbenzene in various matrices are given in Table 1. Ethylbenzene can be determined in biological material (blood, subcutaneous fat, plant foliage, fish samples) using head-space gas chromatography (GC), GC with mass spectrometry, and GC with flame ionization detection (WHO, 1996a). 

Head-Space Gas Chromatography or Head-Space Mass Spectrometry... 

TMA, its N-oxide and related aliphatic amines like methylamine and dimethylamine in urine may be quantified using head-space gas chromatography [28] or direct injection of the head-space gas into the gas sample injection port of a mass spectrometer [27]. These methods take advantage of the volatility of the amines and evaluate the amine-rich head-space gas generated above the sample by direct injection. The... 

Calibration for the head-space gas chromatography method is based on calibration curves with individual amines in distilled water. Isopropylamine is the internal standard [28]. For the isotope dilution mass spectrometry method [2H9]-TMA is used as the internal standard [27]. 

Zhang AQ, Mitchell SC, Ayesh R, Smith RL (1992) Determination of trimethylamine and related aliphatic amines in human urine by head space gas chromatography. J Chromatogr 584 141-145... 

Richelieu, M., Hoalberg, U., and Nielsen, J. C. (1997). Determination of a-acetolactic acid and volatile compounds by head-space gas chromatography. ]. Dairy Sci. 80, 1918-1925. 

Schoene, K. and Steinhauses, J. 1985. Determination of Henry s law constant of automated head space-gas chromatography. Fresenius Z Anal. Chem. 321, 538-543. 

Residual solvents. Examine by head-space gas chromatography, according to the general procedure (2.2.28), using the standard addition method. The content of chloroform is not more than 50 ppm and the content of methylene chloride is not more than 100 ppm. 

Ettre, L.S., Welter, C., Kolb, B. (1993) Determination of gas-liquid partition coefficients by automatic equilibrium head-space gas chromatography using the phase ratio variation method. Chromatographia 35, 73-84. 

M. Kaye and T. Nevell, Statistical evaluation of methods using head-space gas chromatography for the determination of ethylene oxide, Analyst, 7/0 1067-1071 (1985). 

In studies of the substantivity of nine aroma chemicals in a fabric softener application, head-space gas chromatography showed that benzyl salicylate, aldehyde C12 MNA, lilial, musk ketone, and the synthetic musk Fixolide were lost to a far lesser extent upon drying than were alpha ionone, eugenol, or linalool (Muller, Neuner-Jehle, and Etzweiler, 1992) (Figure 13.2). This result corresponds to the relative vapor pressures of these materials, except for aldehyde C12 MNA which is a special case. 

Pekari K, Riekkola M-L, Aitio A. 1989. Simultaneous determination of benzene and toluene in blood using head-space gas chromatography. J Chromatogr 491 309-320. 

Some compounds which are gases at normal temperature and pressure can be detected by head-space gas chromatography (p. 187), using Systems GA or GI (p. 199). System GI will detect butane, ethane, methane, nitrous oxide, and propane, and... 

Only two poisons in this group require routine exclusion. These are cyanide and carbon monoxide. The main exceptions to diis general recommendation are cases arising from an incident on industrial premises, or the use and abuse of compressed solvent fuels and aerosols. In the former case, a list of the industrial gases used or available on site should be requested in die latter case, most of the relevant compounds are covered by head-space gas chromatography as mentioned above. 

The use of calciiun c bide a(hninistered orally in gelatin capsules to horses has been reported in Australia. Acetylene cm be detected by head-space gas chromatography of plasma. 

Capella, R Lercker, G. Lerici, C. R. Aroma retention during freeze-drying of fruit juices volatiles behaviour evaluated by head-space gas chromatography. IV International Congress of Food Science and Technology 5b, 18 (1974)... 

Westerberg E. Larsson L. 1982. Use of automated head-space gas chromatography for determination of 1,1,1-trichloroethane in rat blood and brain tissue. Int J Environ Anal Chem 12 3-4. 

Head space gas chromatography (HSGC) Is an interesting alternative to the automation of sample Introduction In gas chromatography [29]. It relies on the... 

IGC at finite concentrations, and head-space gas-chromatography (HSGC), ebulliometry and... 

Figure 4.4.13. Schematic of applying head-space gas-chromatography (HSGC) to VLE-measurements in polymer solutions (drawing provided by B. A. Wolf, Univ. Mainz, Germany).

Head-space gas chromatography is a modem tool for the measurement of vapor pressures in polymer solutions that is highly automated. Solutions need time to equilibrate, as is the case for all vapor pressure measurements. After equihbration of the solutions, quite a lot of data can be measured continuously with reliable precision. Solvent degassing is not necessary. Measurements require some experience with the equipment to obtain really thermodynamic equihbrium data. Calibration of the equipment with pure solvent vapor pressures may be necessary. HSGC can easily be extended to multi-component mixtures because it determines all components in the vapor phase separately. 

In order to validate the system, external sampling under pressure during the reaction was performed. The reactant contents were analyzed by dynamic head space gas chromatography and the polymer molecular weight distribution by size exclusion chromatography with triple detection. 

Strains for nse in dairy applications are examined for their ability to acidify milk at varions temperatnres in microtiter plates. The change in the pH of the milk is followed by the inclnsion of pH indicators (bromocresol pnrple and bromocresol green) in the milk and scanning on a flatbed scanner typically at 6-min intervals. The data are exported to a snitable spreadsheet such as Microsoft Excel (Microsoft Corporation, Redmond, WA, USA) for ease of calculation. Acidification curves are obtained, and descriptors like total pH drop, maximum acidification rate, and specific time intervals snch as time to acidify from pH 6.0 to pH 5.5 are easily derived in the spreadsheet. The formation of volatile organic compounds in the acidified milk is measured by head space gas chromatography, allowing quantitative assessment of the production of relevant metabolites such as acetaldehyde, acetoin, and 3-methyl-butanal. Tolerance to NaCl is also tested in milk by following the acidification in the presence and absence of 4% (w/v) NaCl. 

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