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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.
In chromatography, the area of a peak is proportional to the number of moles (n) times some constant of proportionality (k), Area = k×n. The number of moles of compound is equal to the concentration (molarity, M) times the volume, n = MV. From these equations, the following derivation is made:
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 ]
In gas chromatography-mass spectrometry (GC-MS), deuterated compounds with similar structures to the analyte commonly act as effective internal standards. [8] However, there are non-deuterated internal standards such as norleucine , which is popular in the analysis of amino acids because it can be separated from accompanying peaks.
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 ...
By measuring any two of these solutions, the unknown concentration is calculated. [ 1 ] As polarographic standard addition involves using only one solution with the standard added – the two-level design, polarographers always refer to the method as singular, standard addition.
Blood alcohol content (BAC), also called blood alcohol concentration or blood alcohol level, is a measurement of alcohol intoxication used for legal or medical purposes. [1] BAC is expressed as mass of alcohol per volume of blood. In US and many international publications, BAC levels are written as a percentage such as 0.08%, i.e. there is 0.8 ...
Headspace technology is a technique developed in the 1980s to elucidate the odor compounds present in the air surrounding various objects. Usually the objects of interest are odoriferous objects such as plants, flowers and foods. [ 1 ]