High-performance liquid chromatography separation

Issaq, H.J., Chan, K.C., Janini, G.M., Muschik, G.M. (1999). A simple two-dimensional high performance liquid chromatography/high performance capillary electrophoresis set-up for the separation of complex mixtures. Electrophoresis 20, 1533-1537. 

High-Performance Liquid Chromatography High-performance liquid chromatography (HPLC) is the preeminent analytical separation technique in pharmaceutical chemistry that delivers the fundamental impurity information for reference standard qualification. Numerous excellent reviews and texts are available54-58 as is a general chapter in the USP.59... 

Siitfeld, R., Preparative liquid chromatography with analytical separation quality interval injection/displacement reversed-phase high-performance liquid chromatography, ]. Chromatogr., 464, 103, 1989. 

Cloud point extraction has been applied to the separation and preconcentration of analytes including metal ions, pesticides, fungicides, and proteins from different matrices prior to the determination of the analyte by techniques such as atomic absorption, gas chromatography, high performance liquid chromatography, capillary zone electrophoresis, etc. 

Assay of bile acids was an essential tool for the early investigation of the enterohepatic circulation, and proved a focus of attention with the belief that serum bile-acid concentrations would provide a sensitive diagnostic test for liver disease. There are three fundamental assay types, based on enzymatic oxidation of a hydroxyl with linked NAD reduction, chromatographic separations and quantitation, encompassing both gas-liquid and high-performance liquid chromatography, and radioimmunoassay assays. 

Achiral (separation of diastereomeric derivatives) and chiral (sepa-ration of enantiomers) chromatography gas chromatography high-performance liquid chromatography super- and sub-critical fluid chromatography thin-layer chromatography... 

Certain classes of lipids are susceptible to degradation under specific conditions. For example, all ester-linked fatty acids in triacylglycerols, phospholipids, and sterol esters are released by mild acid or alkaline treatment, and somewhat harsher hydrolysis conditions release amide-bound fatty acids from sphingolipids. Enzymes that specifically hydrolyze certain lipids are also useful in the determination of lipid structure. Phospholipases A, C, and D (Fig. 10-15) each split particular bonds in phospholipids and yield products with characteristic solubilities and chromatographic behaviors. Phospholipase C, for example, releases a water-soluble phosphoryl alcohol (such as phosphocholine from phosphatidylcholine) and a chloroform-soluble diacylglycerol, each of which can be characterized separately to determine the structure of the intact phospholipid. The combination of specific hydrolysis with characterization of the products by thin-layer, gas-liquid, or high-performance liquid chromatography often allows determination of a lipid structure. 

In the determination of lipid composition, the lipids are first extracted from tissues with organic solvents and separated by thin-layer, gas-liquid, or high-performance liquid chromatography. 

Immobilization. The ability of cyclodextrins to form inclusion complexes selectively with a wide variety of guest molecules or ions is well known (1,2) (see Inclusion COMPOUNDS). Cyclodextrins immobilized on appropriate supports are used in high performance liquid chromatography (hplc) to separate optical isomers. Immobilization of cyclodextrin on a solid support offers several advantages over use as a mobile-phase modifier. For example, as a mobile-phase additive, p-cyclodextrin has a relatively low solubility. The cost of y- or a-cyclodextrin is high. Furthermore, when employed in thin-layer chromatography (dc) and hplc, cyclodextrin mobile phases usually produce relatively poor efficiencies. 

High-performance liquid chromatography can sometimes separate atropi-somers, i.e., a compound with highly hindered rotation about a single bond, producing effectively two molecular species. 

Moreover, it is possible to lead these compounds into the diastereomeric esters or amides using of optically active acid anhydrides. In this case, the diastereomers with a covalent bond need not always necessarily be a crystalline compound because there are still some other methods left to separate these diastereomers, such as thin layer chromatography, high-performance liquid chromatography, etc. 

High Performance Liquid Chromatography HPLC can separate and resolve TC-HC1 from its degradation products ETC, ATC, EATC sensitively and reproducibly. The technique... 

High-performance liquid chromatography and advanced separation technologies... 

Das, D.K., Naturally occurring flavonoids structure, chemistry, and high performance liquid chromatography methods for separation and characterization. Methods Enzy-moL, 234, 410, 1994. 

Many of the most important chemical questions in the pharmaceutical industry involve the analysis of complex mixtures. Identification of low-level metabolites and drug substance impurities usually requires high-performance liquid chromatography for the separation of these mixtures or isolation of a compound of interest from a sample matrix. In these analyses, the structural information obtainable for the low-level compounds is limited by the type of detection used. The coupling of HPLC and mass spectrometry has become routine and provides useful molecular weight and fragmentation information, but this is often not enough for complete structure elucidation. 

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