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Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, or separating the different components of a mixture. [ 1 ]
The method uses headspace gas injected into a gas chromatographic column (GC) to determine the original concentration in a water sample. [9] A sample of water is collected in the field in a vial without headspace and capped with a Teflon septum or crimp top to minimize the escape of volatile gases. It is beneficial to store the bottles upside ...
Unresolved complex mixture (UCM), or hump, is a feature frequently observed in gas chromatographic (GC) data of crude oils and extracts from organisms exposed to oil. [1] The reason for the UCM hump appearance is that GC cannot resolve and identify a significant part of the hydrocarbons in crude oils. The resolved components appear as peaks ...
Gas chromatography–mass spectrometry (GC–MS) is an analytical method that combines the features of gas-chromatography and mass spectrometry to identify different substances within a test sample. [1] Applications of GC–MS include drug detection, fire investigation, environmental analysis, explosives investigation, food and flavor analysis ...
Analytical thermal desorption, known within the analytical chemistry community simply as "thermal desorption" (TD), is a technique that concentrates volatile organic compounds (VOCs) in gas streams prior to injection into a gas chromatograph (GC). It can be used to lower the detection limits of GC methods, and can improve chromatographic ...
General chemistry professors have been known to make tests worth a large portion of the course, and make them more challenging than the material presents itself as. Grade deflation, purposely adjusting the grades of a course to be lower, is also an issue of general chemistry courses at the undergraduate level.
The invariance properties of molecular descriptors can be defined as the ability of the algorithm for their calculation to give a descriptor value that is independent of the particular characteristics of the molecular representation, such as atom numbering or labeling, spatial reference frame, molecular conformations, etc. Invariance to molecular numbering or labeling is assumed as a minimal ...
In chemistry, functionality is the presence of functional groups in a molecule. A monofunctional molecule possesses one functional group, a bifunctional (or difunctional) two, a trifunctional three, and so forth. In organic chemistry (and other fields of chemistry), a molecule's functionality has a decisive influence on its reactivity.