Time gas chromatography

Photochemistry of Model Compounds. Preliminary photochemical studies have been carried out on l,3-diphenoxy-2-propanol (3)8 as a model compound for bisphenol A-epichloro-hydrin condensates 1. The utilization of 3 as a model compound for thermal degradation of 1 has been reported. Irradiation (254 nm) of 3 in acetonitrile (N2 purge) provides two major volatile products, which have been identified as phenol and phenoxyacetone (4), by comparison of retention times (gas chromatography) with known samples. A possible mechanism for... 

Real-time gas chromatography On-stream fixed-filter UV-Vis photometry 1 950s and 1 950s Chemical/petrochemical... 

In summary9 while HPLC techniques hold the greatest promise of short analysis times and the convenience of no derivatization of samples, these techniques are not yet available. At this time, gas chromatography using covalently bonded chiral stationary phases is the method of choice. This method is sufficiently accessible that measurement of racemlzatlon in protein materials can be done on a routine basis. The current state-of-the-art in isomer analysis is this gas chromatographic technique coupled with mass spectrometry. 

Real-Time Gas Chromatography-High Resolution Mass Spectrometry and Its Application to the Analysis of Physiological Fluids Adv. Mass Spectrom. Biochem. Med. 1 565-576 (1976) CA 85 59014r... 

The commercial value of fuels in general and fuel gases in particular depends on the amount of energy contained in a given amount of fuel. Traditionally, this amount of energy per unit amount, the calorific value, has been determined by gas calorimetry (Hyde and Jones, 1960). In recent times, gas chromatography... 

At the present time, gas chromatography-mass spectrometry (GC-MS) is the most versatile analytical technique for the solution of this problem. In an on-line operation each component separated and eluted from the gas chromatograph can be individually scanned by the mass spectrometer (MS) to give a mass spectrum which will definitely identify the component by comparison with reference data. There are a number of potential advantages inherent in the combined use of GC and MS which are listed below, and these have been applied to the multicomponent analysis of many different compound classes. 

Gas chromatography is not an identification method the components must be identified after their separation by capillary column. This is done by coupling to the column a mass spectrometer by which the components can be identified with the aid of spectra libraries. However tbe analysis takes a long time (a gasoline contains aboutTwo hundred components) so it is not practical to repeat it regularly. Furthermore, analysts have developed te hpiques for identifying... 

A chromatographic column provides a location for physically retaining the stationary phase. The column s construction also influences the amount of sample that can be handled, the efficiency of the separation, the number of analytes that can be easily separated, and the amount of time required for the separation. Both packed and capillary columns are used in gas chromatography. 

Time, Cost, and Equipment Analysis time can vary from several minutes for samples containing only a few constituents to more than an hour for more complex samples. Preliminary sample preparation may substantially increase the analysis time. Instrumentation for gas chromatography ranges in price from inexpensive (a few thousand dollars) to expensive (more than 50,000). The more expensive models are equipped for capillary columns and include a variety of injection options and more sophisticated detectors, such as a mass spectrometer. Packed columns typically cost 50- 200, and the cost of a capillary column is typically 200- 1000. 

Py/GC/MS. pyrolysis, gas chromatography, and mass spectrometry used as a combined technique Py/MS. pyrolysis and mass spectrometry used as a combined technique oa-TOF. orthogonally accelerated time of flight Q. quadrupole field or instrument... 

Gas Chromatography (gc). A principal advantage of gas chromatography has been the faciUty with which it can be combined with mass spectrometry for amino acid identification and confirmation of purity. The gc-mass spectrometry combination offers the advantage of obtaining stmctural information rather than the identification by retention time in hplc. 

Coimnonly used methods for tlie measurement of pestieides in water samples involve. Solid Phase Exttaetion (SPE) followed by Gas Chromatography or High Performanee Liquid Cliromatography (HPLC) analysis. SPE is a multiple step proeedure and, thus, time eonsuming. 

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