Quaternary ammonium compounds chromatographic

Numerous chromatographic methods coupled with MS have been developed for quaternary ammonium compounds. HPLC and fast atom bombardment mass spectrometry (FAB-MS) techniques have been applied to analyse concentrations of alkyldimethylbenzyl ammonium... 

In the field of cation analysis, ion-pair chromatography is the preferred method for the separation of amines of all types. While short-chain aliphatic amines (C3 to C3) and some smaller aromatic amines [39] can also be separated on surface-sulfonated cation exchangers, ion-pair chromatographic applications have been developed for the separation of structurally isomeric amines, alkanolamines, quaternary ammonium compounds, arylalkylamines, barbiturates, and alkaloids. 

Quaternary ammonium compounds can be analyzed under similar chromatographic conditions, but without adding boric acid. This includes choline (2-hydroxyethyl-trime-thylammonium hydroxide), which is commonly found in fauna and flora as a basic constituent of lecithin-type phospholipids. The ion-pair chromatographic separation of choline requires an eluent that, in addition to hexanesulfonic acid as the ion-pair re-... 

The lonPac CS12A cation exchanger can also be used to separate quaternary ammonium compounds (Figure 4.85). The chromatographic conditions are very similar to those described in Figure 4.84. Because quaternary ammonium compounds have a much larger carbon backbone, hydrophobic interactions with the stationary phase are so strong that an increase in eluent acid concentration does... 

In the past, these types of cationic surfactants have played only a secondary industrial role, but are increasingly employed in recent years. In the past, not many liquid chromatographic methods for separating such compounds were foimd in the literature. Because these quaternary ammonium compounds are comparably hydrophobic, hydrochloric acid is used as the ion-pair reagent in their separation. Perfluorinated carboxylic acids are also used from time to time. Because of the lack of suitable chromophores, quaternary ammonium compounds can be sensitively detected only by measuring the electrical conductivity. Figure 6.44 shows a separation of a number of aliphatic quaternary ammonium compoimds it was... 

As an example of cationic surfactant analysis in finished products. Fig. 9-125 shows the separation of alkylbenzyl-dimethyl-ammonium compounds in a toilet cleaner. As can be seen from the respective chromatogram, this raw material basically consists of two species, the C12- and the Ci4-component. Thus, chromatographic separation is much simpler than shown above for alkyl sulfonates. Because these long-chain quaternary ammonium compounds exhibit a marked hydrophobicity, surface-inactive hydrochloric acid is used as an ion-pair reagent. 

In the last decade modifications to the pyrolysis process have been developed to improve analytical efficiency and increase detectability. In the same way as in conventional GC, derivatization reagents may be used to improve the chromatographic separation and response of polar compounds. In order to reduce the time required for the analysis, the risk of contamination and of losing part of the sample, on-line derivatization methods should be preferred and those based on quaternary ammonium hydroxides are certainly the most widely used. 

In recent years, a new class of ILs based on tricaprylammonium chloride (Ali-quat 336) has been investigated. By a simple replacement of the chloride anion, several new ILs have been generated and tested for their applicability, for instance, as extracting agents for heavy metals [641]. However, difficulties arise in the course of the analysis of Aliquat-based ILs as Aliquat 336 is a mixture of quaternary ammonium cations with different alkyl chain lengths rather than a well-defined pure compound. This property makes the quantification of the Aliquat cation and hence all of its products more comphcated. On the other hand, ILs based on quaternary phosphonium cations are already in use for a varietjr of applications. So far, no apphcable LC characterization and/or purity determination of these two classes of ILs was mentioned in literature. In 2008, Stojanovic et al. [642] introduced a reversed-phase liquid chromatographic method with serially coupled diode array detection (DAD) and charged aerosol detection for... 

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