Gas chromatography-mass spectrometry interfacing

Always use graphite/vespel ferrules when connecting a column to a gas chromatography-mass spectrometry interface. 

The possibiHties for multidimensional iastmmental techniques are endless, and many other candidate components for iaclusion as hyphenated methods are expected to surface as the technology of interfacing is resolved. In addition, ternary systems, such as gas chromatography-mass spectrometry-iafrared spectrometry (gc/ms/ir), are also commercially available. 

Gas chromatography/mass spectrometry (GC/MS) is the synergistic combination of two powerful analytic techniques. The gas chromatograph separates the components of a mixture in time, and the mass spectrometer provides information that aids in the structural identification of each component. The gas chromatograph, the mass spectrometer, and the interface linking these two instruments are described in this chapter. 

Merritt DA, KH Freeman, MP Ricci, SA Studley, JM Hayes (1995) Performance and optimization of a combustion interface for isotope ratio monitoring gas chromatography/mass spectrometry. Anal Chem 67 2461-2473. 

Total adsorbate analysis was performed on a sample of parent H-mordenite deactivated with cumene by interfaced gas chromatography-mass spectrometry. The deactivated catalyst was dissolved in 48% hydrofluoric acid at 0°C, and the organics released were extracted into chloroform. Prior to analysis, a small volume of this solution was taken up into a capillary tube, and the chloroform was allowed to evaporate, leaving a thin... 

Frequently industrial hygiene analyses require the identification of unknown sample components. One of the most widely employed methods for this purpose is coupled gas chromatography/ mass spectrometry (GC/MS). With respect to interface with mass spectrometry, HPLC presently suffers a disadvantage in comparison to GC because instrumentation for routine application of HPLC/MS techniques is not available in many analytical chemistry laboratories (3). It is, however, anticipated that HPLC/MS systems will be more readily available in the future ( 5, 6, 1, 8). HPLC will then become an even more powerful analytical tool for use in occupational health chemistry. It is also important to note that conventional HPLC is presently adaptable to effective compound identification procedures other than direct mass spectrometry interface. These include relatively simple procedures for the recovery of sample components from column eluate as well as stop-flow techniques. Following recovery, a separated sample component may be subjected to, for example, direct probe mass spectrometry infra-red (IR), ultraviolet (UV), and visible spectrophotometry and fluorescence spectroscopy. The stopped flow technique may be used to obtain a fluorescence or a UV absorbance spectrum of a particular component as it elutes from the column. Such spectra can frequently be used to determine specific properties of the component for assistance in compound identification (9). 

PG. Simmonds, G.R. Shoemake, and J.E. Lovelock, Palladium hydrogen system Efficient interface for gas chromatography-mass-spectrometry. Anal. Chem. 42 881 (1970). 

Analytical pyrolysis requires heating of the sample at a temperature significantly higher than ambient. Commonly selected temperatures are between 500° C and 800° C, but for special purposes this temperature can be higher or lower. The pyrolytic process is done in a pyrolysis unit (pyrolyzer), which has a source of heat. The pyrolyzer is interfaced on-line or off-line with an analytical instrument, which is used for the measurement of the pyrolysis products. Common techniques applied for this purpose are gas chromatography (GC), gas chromatography/mass spectrometry (GC/MS), mass spectrometry (MS), etc. Pyrolysis GC/MS (Py-GC/MS) is probably the most common technique in analytical pyrolysis. 

Chemical Analysis. Gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) techniques were used to analyze 4-chlorophenol and its oxidation intermediates. For GC-MS analysis, the samples were acetylated in pyridine. The samples were first evaporated to dryness. Then 200 xL of pyridine and 200 (xL of acetic anhydride were added to the dry residue. The samples were heated at 65 °C for 2-3 h to ensure the complete acetylation reaction, and then gently evaporated to dryness in a nitrogen stream. Finally, the residue was redissolved in 0.1 mL of hexane for GC analysis. A GC (HP model 5890) equipped with mass selective detector (HP model 5971) and SPB-5 capillary column (Supelco Co., PA., 25- X 0.2-mm i.d. X 0.33-p.m film thickness) was used. To separate different intermediate products, various oven-temperature programs were performed. The GC-MS interface line was maintained at 300 °C. The mass-... 

C per minute injection port temperature, 270°C carrier gas, helium flow rate, 1 ml/min and MS conditions-scan mode, ionization energy, 70 eV ion source temperature 220°C capillary direct interface heated at 260°C. After acid hydrolysis of the conjugates, extraction, and acetylation, the urine samples were analyzed by computerized gas chromatography-mass spectrometry. The presence of aUcylamine antihistamines and their metabolites were indicated with the selected ions m/z 58, 169, 203, 205, 230, 233, 262, and 337. 

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