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GC is a method involving the separation of different analytes within a sample of mixed gases. The separated gases can be detected multiple ways, but one of the most powerful detection methods for gas chromatography is mass spectrometry. After the gases separate, they enter the mass spectrometer and are analyzed.
The results are presented as a mass spectrum, a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures. A mass spectrum is a type of plot of the ion signal as a function of the mass-to-charge ratio.
Mass spectral interpretation is the method employed to identify the chemical formula, characteristic fragment patterns and possible fragment ions from the mass spectra. [1] [2] Mass spectra is a plot of relative abundance against mass-to-charge ratio. It is commonly used for the identification of organic compounds from electron ionization mass ...
Electron ionization mass spectrum of toluene. Note parent peak corresponding to molecular mass M = 92 (C 7 H 8 +) and highest peak at M-1 = 91 (C 7 H 7 +, quasi-stable tropylium cation). A mass spectrum is a histogram plot of intensity vs. mass-to-charge ratio (m/z) in a chemical sample, [1] usually acquired using an instrument called a mass ...
Cooling the gas allows for a large amount of moisture from the brine to condense out of the gas stream. Cooling also improves the efficiency of both the compression and the liquefaction stage that follows. Chlorine exiting is ideally between 18°C and 25°C. After cooling the gas stream passes through a series of towers with counter flowing ...
Sometimes two different molecules can also have a similar pattern of ionized fragments in a mass spectrometer (mass spectrum). Combining the two processes reduces the possibility of error, as it is extremely unlikely that two different molecules will behave in the same way in both a gas chromatograph and a mass spectrometer.
It is a colourless gas that melts at −155.6 °C and boils at −100.1 °C. It may be produced by the reaction of its elements at 225 °C, though it must then be separated and purified from chlorine trifluoride and its reactants. Its properties are mostly intermediate between those of chlorine and fluorine.
Chemical ionization in an atmospheric pressure electric discharge is called atmospheric pressure chemical ionization (APCI), which usually uses water as the reagent gas. An APCI source is composed of a liquid chromatography outlet, nebulizing the eluent, a heated vaporizer tube, a corona discharge needle and a pinhole entrance to 10 −3 torr ...