Liquid chromatography High

HPLC High liquid chromatography, ED electrochemical detector, ESI electrospray ionization, MS tandem mass spectrometry, LPT Liquid-phase sorbent trapping, TD Thermal desorption, GC Gas chromatography, TLC Thin layer chromatography, DAD Diode Array, FD Fluorescence detection, FTIR Fourier transform infrared spectroscopy, SPME Solid phase microextraction... 

HPLC High pressure liquid chromatography. Hudson s isorotadon rule For a pair of sugars... 

Liquid chromatography is preceded by a precipitation of the asphaltenes, then the maltenes are subjected to chromatography. Although the separation between saturated hydrocarbons and aromatics presents very few problems, this is not the case with the separation between aromatics and resins. In fact, resins themselves are very aromatic and are distinguished more by their high heteroatom content (this justifies the terms, polar compounds or N, S, 0 compounds , also used to designate resins). 

High-Performance liquid Chromatography. Typical performances for various experimental conditions are given in Table 11.15. The data assume these reduced parameters h = 3, V = 4.5. The reduced plate height is... 

The second set of experiments describes the application of high-performance liquid chromatography. These experiments encompass a variety of different types of samples and a variety of common detectors. 

Tran, C. D. Dotlich, M. Enantiomeric Separation of Beta-Blockers by High Performance Liquid Chromatography, ... 

The following references may be consulted for more information on high-performance liquid chromatography. 

For mixture.s the picture is different. Unless the mixture is to be examined by MS/MS methods, usually it will be necessary to separate it into its individual components. This separation is most often done by gas or liquid chromatography. In the latter, small quantities of emerging mixture components dissolved in elution solvent would be laborious to deal with if each component had to be first isolated by evaporation of solvent before its introduction into the mass spectrometer. In such circumstances, the direct introduction, removal of solvent, and ionization provided by electrospray is a boon and puts LC/MS on a level with GC/MS for mixture analysis. Further, GC is normally concerned with volatile, relatively low-molecular-weight compounds and is of little or no use for the many polar, water soluble, high-molecular-mass substances such as the peptides, proteins, carbohydrates, nucleotides, and similar substances found in biological systems. LC/MS with an electrospray interface is frequently used in biochemical research and medical analysis. 

The solvents used for liquid chromatography are the commoner ones such as water, acetonitrile, and methanol. For the reasons just stated, it is not possible to put them straight into the ion source without problems arising. On the other hand, the very viscous solvents that qualify as matrix material are of no use in liquid chromatography. Before the low-boiling-point eluant from the LC column is introduced into the ion source, it must be admixed with a high-boiling-point matrix... 

For liquid chromatography, a sample of the mixture solution is injected through a loop injector which allows a quantity of the solution to be placed in a small tubular loop at atmospheric pressure. By manipulating a valve, the high-pressure flow of solvent to the column is diverted through the loop, carrying the sample with it (Figure 35.5). 

Practical inlet systems for attaching a high-pressure liquid chromatography (HPLC) column to a mass spectrometer utilize atmospheric-pressure ionization (see Chapters 8 and 11). 

A flow of liquid, for example from high-performance liquid chromatography (HPLC), is treated in such a way that most of the solvent evaporates to leave solute molecules that pass into an ionization region (ion source). 

High-pressure liquid chromatography (HPLC) is simply a variant on LC in which the moving liquid stream is forced along under high pressure to obtain greater efficiency of separation. 

LC, or sometimes HPLC (high-pressure liquid chromatography), is a means of separating components of mixtures by passing them in a solvent through a chromatographic column so that they emerge sequentially. 

GD/IRMS. glow discharge isotope ratio mass spectrometry HPLC. high-pressure liquid chromatography... 

High Performance Liquid Chromatography. Although chiral mobile phase additives have been used in high performance Hquid chromatography (hplc), the large amounts of solvent, thus chiral mobile phase additive, required to pre-equiUbrate the stationary phase renders this approach much less attractive than for dc and is not discussed here. 

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