GC/MS gas chromatography with mass

US EPA published its initial list of 187 organic compounds found in US drinking water in 1975. Analyses were performed using GC-MS (gas chromatography with mass spectroscopy) and a packed column to separate organic compounds. Present-day analyses using a capillary column to separate compounds have increased the resolution of GC-MS detection several fold (7). 

The six most commonly used analytical techniques are biological assays, radioimmunoassays, radiochromatography after incubation of tissues in vitro with arachidonic acid, gas chromatography/mass spectrometry (GC-MS), gas chromatography with electron capture detection and recently, high performance liquid chromatography (HPLC). The last is used... 

Identification of stmctures of toxic chemicals in environmental samples requires to use modern analytical methods, such as gas chromatography (GC) with element selective detectors (NPD, FPD, AED), capillary electrophoresis (CE) for screening purposes, gas chromatography/mass-spectrometry (GC/MS), gas chromatography / Fourier transform infra red spectrometry (GC/FTIR), nucleai magnetic resonance (NMR), etc. 

GC-MS gas chromatography coupled with mass spectrometry HDL heavy-duty liquid or laundry liquid... 

Scientists need to classify and organize complex data, such as that yielded by medical tests or analysis via GC-MS (gas chromatography-mass spectrometry). The data may be multifaceted and difficult to interpret, as different tests may conflict or yield inconclusive results. Growing cell structures may be used to assess medical data for example, such as that obtained from patient biopsies, and determine whether the test results are consistent with a diagnosis of breast cancer.1... 

GC-EAD Gas chromatography combined with an EAG detector GC-MS Gas chromatography combined with mass spectrometry HPLC High performance liquid chromatography KI Kovats retention index... 

Test methods that analyze individual compounds (e.g., benzene-toluene-ethylbenzene-xylene mixtures and PAHs) are generally applied to detect the presence of an additive or to provide concentration data needed to estimate environmental and health risks that are associated with individual compounds. Common constituent measurement techniques include gas chromatography with second-column confirmation, gas chromatography with multiple selective detectors, and gas chromatography with mass spectrometry detection (GC/MS) (EPA 8240). 

Mass spectrometry (MS) is probably a famhiar tool to chemistry and biology students as a technique commonly used to measure the molecular mass of a sample. Often, MS is used in tandem with other techniques for chromatic separation of the sample before mass measurement. Some common hyphenated techniques include HPLC-MS, high-pressure liquid chromatography coupled to MS GC-MS, gas chromatography coupled to MS or CE-MS, capillary electrophoresis coupled to MS. 

As already mentioned, it is the volatile constituents that serve to identify fruit type and variety. Broadly speaking, qualitative analysis will identify the principal substances present in the volatiles fraction as representative of a particular fruit type, but it is the relative proportions of these substances that will reflect the variety. Alcohols, volatile acids, esters, carbonyl compounds, and low-boiling hydrocarbons are the principal groups represented. Analysis by GC-MS (gas chromatography coupled with mass spectroscopy) can be used to provide quantification and identification of the various constituents. 

G. S. Frysinger and R. B. Gaines, Comprehensive two-dimensional gas chromatography with mass spectrometric detection (GC X GC/MS) applied to the analysis of petroleum , J. High Resolut. Chromatogr. 22 251-255 (1999). 

Figure 13.19 Chromatograms obtained by on-line SPE-GC-MS(SIM) of (a) 10 ml of tap water spiked with pesticides at levels of 0.1 ng 1 1 (b) 10 ml of a sample of unspiked tap water. Peak identification for (a) is as follows 1, molinate 2, a-HCH 3, dimethoate 4, simazine 5, atrazine 6, y-HCH 7, 8-HCH 8, heptachlor 9, ametryn 10. prometryn 11, fen-itrothion 12, aldrin 13, malathion 14, endo-heptachlor 15, a-endosulfan 16, tetrachlor-vinphos 17, dieldrin. Reprinted from Journal of Chromatography, A 818, E. Pocurull et al., On-line coupling of solid-phase extraction to gas chromatography with mass spectrometric detection to determine pesticides in water , pp. 85-93, copyright 1998, with permission from Elsevier Science.

GC-MS (gas chromatography-mass spectrometry) is widely used in the analysis of complex mixtures of organic compounds. Such a system is operating with a carrier gas (He) flow through the column of 20 atm ccmin-1 at 293 K. Since the pressure requirements of the GC and the MS differ by several orders of magnitude, two possible systems are considered (see diagrams (a) and (b)). 

The focus of most archaeological ceramic studies has been on provenance or technology. There is also a growing body of specific evidence on how the pottery was used. Chapter 21 by Beck, Smart, and Ossenkop describe the organic tars used to line ancient Mediterranean amphoras. Chapter 21 includes a description of how the residues from amphora contents can be analyzed. As in most cases where unknown organic materials are encountered, the most powerful analytical technique is gas chromatography with mass spectrometric detection (GC-MS). This technique is expensive for the analysis of large numbers of samples. 

In 2002 extensive kinetic and product studies on the reactions of gaseous Hg with molecular and atomic halogens (X/X2 where X = Cl, Br) were performed at atmospheric pressure (750 1 Torr) and room temperature (298 1 K) in air and N2 [24]. Kinetics of fhe reactions with X/X2 were studied using both relative and absolute techniques. Cold vapour atomic absorption spectroscopy (CVAAS) and gas chromatography with mass spectroscopic detection (GC-MS) were the analytical methods applied. The measured rate constants for the reactions of Hg with CI2, Cl, Br2, and Br were (2.6 0.2) x IQ-i , (1.0 0.2) x 10" , < (0.9 0.2) x and (3.2 0.3) x 10 cm molecule s , respectively. Thus CI2 and Br2 are not important reactants in the troposphere for the CI2 and Br2 concentrations reported in literature [24]. 

GC-FID gas chromatography with flame ionization detector, HPLC-UV high performance liquid chromatography with UV detector, LC-MS liquid chromatography coupled with mass spectrometry, GC-FPD gas chromatography with flame photometric detector... 

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