Gas chromatography methods

An attractive method for the analysis of mixtures of enantiomers is chiral gas chromatography (GC). This sensitive method is unaffected by trace impurities, and is quick and simple to carry out. The premise upon which the method is based is that molecular association may lead to sufficient chiral recognition that enantiomer resolution results. The method uses a chiral stationary phase which contains an auxiliary resolving agent of high enantiomeric purity. The enantiomers to be analysed undergo rapid and reversible diastereomeric interactions with the stationary phase and hence may be eluted at different rates. There are certain limitations to the method, some of which are peculiar to the gas chromatographic method. The sample should be sufficiently volatile and thermally stable, and, of course, should be quantitatively resolved on the chiral GC phase. Occasionally this 

Most of the reported applications of this technique involve the direct resolution of derivatised enantiomers on chiral stationary phases. The earliest successful resolution of yV-trifluoroacetyl amino acid esters on glass capillary columns coated with N-trifluoroacetyl-5-isoleucine lauryl ester (2) was effected in 1966. Superior stationary phases developed quickly, such as (3), in which the additional amide bond may interact via hydrogen bonding. These chiral supports work well for the separation of A -perfluoracylated derivatives of a given amino acid. However, their low thermal stability (190 C maximum) and appreciable volatility have inhibited their use for the simultaneous 

Other diamide sub-units have been coupled to polysiloxane backbones leading, for example, to resolution of trifluoroacetyl derivatives of secondary amines and the resolution of alcohols and a-hydroxy acids as their isopropylurethane derivatives after derivatisation with isopropyl isocyanate. Such a method established that commercial (5)-ethyl lactate contained 1.67% of the R enantiomer, i.e. it had an e.e. of 96.66%. 

The direct resolution of underivatised enantiomers has been effected with the aid of some metal-containing chiral stationary phases. Particular attention has been paid to the resolution of chiral alkenes and epoxides using stationary phases derived from chiral metal chelate complexes. The rhodium dicarbonyl P-diketonate complex (5), when dissolved in squalene and coated onto a capillary column, permitted the quantitative enantiomer resolution of 3-methylcyclopentene while methyl oxirane was similarly resolved 

The development of rapid, simple liquid chromatography methods for the assay of enantiomeric purity has perhaps been the most important development in the analysis of chiral compounds in the last 

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Gortseva LV, Tarasova NA, Shutova TV, et al. 1987. [Determination of acrylonitrile in polymer materials and aqueous and oily extracts of them by the gas-chromatography method.] Gig Sanit 61-62. (Russian)... 

Verevkin, S.P., Wandschneider, D., Heintz, A. (2000) Determination of vaporization enthalpies of selected linear and branched C7, C8, C9, Cu and Cu monoolefin hydrocarbons from transpiration and correlation gas-chromatography methods. J. Chem. Eng. Data 45, 618-625. 

EPA. 1990b. Chlorinated hydrocarbons by gas chromatography. Method 8120A. Washington, DC U.S. Environmental Protection Agency, 1-16. 

Using the gas chromatography methods Sackmayereva et al. [30] obtained from spiked samples the four BHC isomers at 93-103.5% recovery. Both DDT and DDE were yielded in 85.6-94%, 90-93.2%, 90-102.4% and 92-105.8% from sediment. Purification on a Florisil column was used in determining chlorinated insecticides unstable at low pH (Aldrin, Dieldrin). The type and activity of Florisil influence the yield and accuracy of the method. Therefore, the activity of this adsorbent had to be verified and adjusted [36, 37],... 

The flash evaporation pyrolysis gas chromatography method [16] as described in section 11.1.4 for the determination of polycyclic aromatic hydrocarbons, haloorganics, aliphatic hydrocarbons, heteroaromatics, elemental sulphur and pyrolysis products of synthetic polymers in soils has also been applied to non-saline sediments. 

At the City of Lincoln, Nebraska, Water Treatment Plant Laboratory, the concentrations of various agricultural chemicals found in the raw water, especially herbicides (such as atra-zine) in the water, are important to determine. The method of choice is a gas chromatography method with a nitrogen-phosphorus detector (NPD). 

ASTM. 1988. Standard practice for measuring volatile organic matter in water by aqueous-injection gas chromatography - method D 2908-87. In 1988 annual book of ASTM standards. Vol. 11.02. Water II. Philadelphia, PA American Society for Testing and Materials, 46-51. 

EPA. 1989d. Measurement of volatile aromatic and unsaturated organic compounds in water by purge and trap gas chromatography - method 503.1. Cincinnati, OH U.S. Environmental Protection Agency, Environmental Monitoring Systems Laboratory. 

All analytical methods involve some kind of sample preparation and thus the type of factors selected for a HPLC method as shown in Table 5.2 are similar for all methods. However, different stages in the preparation will be more critical for some methods. For instance, derivatisation will be more common for gas chromatography methods and hence more critical. 

Korytar, R, Janssen, H.G., Matisova, E., Brinkman, U.A.T. (2002) Practical fast gas chromatography methods, instrumentation and applications. Trends Anal. Chem. 21 558-572. 

Glycerin is used in Nasonex primarily as a humectant. For its quantification, both capillary gas chromatography method and HPLC methods may be selected. The GC is equipped with a flame-ionization defector, a 0.53 mm x 30 m fused silica analytical column coated with 3.0-p,mG43 stationary phase, and a 0.53 mm x 5 m silica guard column deactivated with phenylmethyl siloxane. The carrier gas was helium with a linear velocity of about 35 cm/s. The injection port and detector temperature was maintained at 240 and 260°C, respectively. The injection mode is splitless. The column temperature is programmed to be maintained at about 40°C for 20 min, then to increase to 250°C at a rate of 10°C/min and to hold at 250°C for 15 min. 

Table 3.3.1 The following fatty acids can be separated and quantitated using the gas chromatography method...

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]. 

Groff, D. W., Gas Chromatography Methods for Bone Fluorine and Nitro-... 

K Grob, I Kalin. Attempt for an on-line size exclusion chromatography-gas chromatography method for analyzing pesticide residues in food. J Agric Food Chem 39 1950-1953, 1991. 

In situations where impurities have low or no UV chromophores, HPLC-NMR provides a unique window on the separation process. This has been exemplified using a drug substance known as SKF-99085, where HPLC-MS, HPLC-NMR, refractive index, light scattering and gas chromatography methods were all used to quantify and identify impurities [30] ... 

Measurement of Benzene Concentrations. Part 1 Pumped Sampling Followed by Thermal Desorption and Gas Chromatography Method, CEN. 

Kashima, J., Yamazaki, T. Determination of hydrogen in cast iron by the gas chromatography method. Rept. Castings Res. Lab., Waseda Univ. 1961, 21. — Chem. Abstr. 60, 9900(1964). 

S. Markovic and Z. Krisec, Determination of butalbital, caffeine and propyphenozone in pharmaceutical preparations by gas chromatography method, Pharmazie, 46 886 (1991). 

Pozo-Bayon, M. A., Pueyo, E., Martfn-Alvarez, P. J., and Polo, M. C. (2001). Polydimethylsi-loxane solid-phase microextraction-gas chromatography method for the analysis of volatile compounds in wines Its application to the characterization of varietal wines.. Chromatogr. A 922,267-275. 

Cannard and Criddle [195] have described a rapid pyrolysis-gas chromatography method for the simultaneous determination of Paraquat and Diquat in pond and river waters in amounts down to 0.00 lppm. 

Rasmussen [495] has described gas chromatography methods for the identification of hydrocarbon oil spills. The spill samples are analysed on a 30.5m Dexsil-300 support coated open tube (SCOT) column to obtain maximum resolution. 

Roe et al. [510] determined volatile aromatic compounds in groundwaters using a headspace gas chromatography method. 

Air samples are usually collected to solid adsorbents such as Tenax, XAD resins, graphitized carbons (e.g. Carbopak), active charcoal, or porous polymers (e.g. Chromosorb). The chemicals are eluted from the adsorbent to a liquid or gas phase by liquid-solid elution or extraction or by thermal desorption. Extraction is the most common method. Thermal desorption can be applied when analysis is by GC (gas chromatography) method, and, recently, the use of automated thermal desorption has been proposed to provide increased sensitivity in GC/MS analysis of a wide range of CWC-related chemicals 8. ... 

Many techniques are followed to identify and quantify the components of fennel essential oil. Krizman et al. (2006) developed a headspace-gas chromatography method for analysing the major volatile constituents in fennel fruits and leaves — a-pinene, a-phellandrene, limonene, fenchone, estragole and trans-anethole. 

Scheme for Evaluation of the Chromosorb 107-Gas Chromatography Method for Vinyl Acetate... 

A comparison of the Chromosorb 107-gas chromatography method with the infrared analyzer is given by the recoveries calculated for day 1. It is not obvious which method gives measurements... 

Sanches-Silva, A., Rodriquez-Bernaldo de Quiros, A., Lopez-Hemandez, J., Paseiro-Losada, P. 2004. Comparison between high-performance liquid chromatography and gas chromatography methods for fatty acid identification and quantification in potato crisps. J. Chromatogr. A. 1032, 7—15. 

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