Columns high pressure liquid chromatography

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). 

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. 

High Pressure Liquid Chromatography. This modem version of the classical column chromatography technique is also used successfully for separation and quantitative analysis of dyes. It is generally faster than thin-layer or paper chromatography however, it requires considerably more expensive equipment. Visible and uv photometers or spectrophotometers are used to quantify the amounts of substances present. 

High-pressure liquid chromatography (HPLC) is a variant of the simple column technique, based on the discovery that chromatographic separations are vastly improved if the stationary phase is made up of very small, uniformly sized spherical particles. Small particle size ensures a large surface area for better adsorption, and a uniform spherical shape allows a tight, uniform packing of particles. In practice, coated Si02 microspheres of 3.5 to 5 fxm diameter are often used. 

The stationary phase matrices used in classic column chromatography are spongy materials whose compress-ibihty hmits flow of the mobile phase. High-pressure liquid chromatography (HPLC) employs incompressible silica or alumina microbeads as the stationary phase and pressures of up to a few thousand psi. Incompressible matrices permit both high flow rates and enhanced resolution. HPLC can resolve complex mixtures of Upids or peptides whose properties differ only slightly. Reversed-phase HPLC exploits a hydrophobic stationary phase of... 

The open-column technique is commonly applied in the case of crude oils (being the least complex geochemical organic mixtures). MPLC, high-pressure liquid chromatography (HPLC), and PTLC are more often applied to more complex samples, especially those dominated by more polar compounds, such as hydrothermal bitumens or samples showing terrestrial organic matter input, such as extracts or pyroly-sates of coals of various ranks. 

Huber, J.F.K., Van der Linden, R., Ecker, E., Oreans, M. (1973). Column switching in high-pressure liquid chromatography. J. Chromatogr. 83, 267-279. 

DeVoe, H., Miller, M.M., Wasik, S.P. (1981) Generator columns and high pressure liquid chromatography for determining aqueous solubilities and octanol-water partition coefficients of hydrophobic substances. J. Res. Natl. Bur. Std. 86, 361. 

XAD resins have been used to collect and concentrate organic materials from seawater. They can also be used as packings for fractionation by column chromatography. While they have been used in simple gravity flow column chromatography, high pressure liquid chromatography has also been used [74-78]. 

A natural extension of column chromatography is high-pressure liquid chromatography, which combines separation, detection, and quantitation (and isolation in the case of preparatory work). Perhaps the single... 

HPLC. Is it high-performance liquid chromatography or high-pressure liquid chromatography or something else It s probably easier to consider it a delicate blend of wet-column chromatography and gas chromatography (see Chapters 20 and 24, respectively). 

Excreted metabolites are collected on the resin column as a result of both static and steady-state exposures, and their separation is accomplished by thin-layer, gas-liquid, and/or high-pressure liquid chromatography of the eluted residue (Step 4). 

This chapter deals with the properties of high-pressure liquid chromatography columns. It is divided into two sections column physics and column chemistry. In the section on column physics, we discuss the properties that influence column performance, such as particle size, column length and column diameter, together with the effect of instrumentation on the quality of a separation. In the section on column chemistry, we examine in depth the surfaces of modern packings, as well as the newer developments such as zirconia-hased packings, hybrid packings or monoliths. We have also included a short section on... 

Since its creation around 1973, modern high-pressure liquid chromatography (HPLC) has played a dominant role in the analysis of pharmaceuticals. It is used in many different applications for example, in content uniformity assays and stability-indicating methods, for the purity profiles of drug substances, or in the analysis of drug metabolism in animals and humans. The heart of all of these assays is the HPLC column. In this chapter, we will describe the fundamental properties of HPLC columns as well as how these properties influence column performance and separation characteristics in pharmaceutical assays. 

Following the incorporation of a number of modifications, the fluorometric method was utilized in a post column reaction system (PCRS) with separation of the toxins by high pressure liquid chromatography (HPLC) (, ). While this system proved quite useful... 

High pressure liquid chromatography (HPLC) was used for the quantitative measurement of quinones and hydroquinones in the cultures. 20 pi of supernatant were injected in a Merck-Hitachi HPLC system 655A-12 equipped with a 4.6 x 250 mm Nucleosil C18 column (5 pm, RP 18). The system was run at a flow rate of 1 ml min-1 with a methanol/water gradient (10 to 20% methanol in 15 min, then 20 to 100% methanol in 5 min). The UV detector was operated at 281 nm or 275 nm to follow the reduction of quinones 13 and 14, respectively (37). 

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