High-performance liquid definition

Liquid chromatography (LC) and, in particular, high performance liquid chromatography (HPLC), is at present the most popular and widely used separation procedure based on a quasi-equilibrium -type of molecular distribution between two phases. Officially, LC is defined as a physical method... in which the components to be separated are distributed between two phases, one of which is stationary (stationary phase) while the other (the mobile phase) moves in a definite direction [ 1 ]. In other words, all chromatographic methods have one thing in common and that is the dynamic separation of a substance mixture in a flow system. Since the interphase molecular distribution of the respective substances is the main condition of the separation layer functionality in this method, chromatography can be considered as an excellent model of other methods based on similar distributions and carried out at dynamic conditions. 

For each dmg substance, the maximum acceptable levels of the various impurities are described in the drug substance monograph or the specification included in the submissions to the regulatory authorities. In this chapter, the ICH Q6A [4] and Q6B [5] definition of specification is used. A specification consists of three parts the test (e.g. moisture content, impurities), references to the analytical procedure (e.g. high-performance liquid chromatography [HPLC], gas chromatography [GC]), and the acceptance criterion (e.g. not more than 0.50%). 

High-performance liquid chromatography (HPLC) has become a standard separation technique used in both academic and commercial analytical laboratories. However, there are several drawbacks to standard HPLC, including high solvent consumption, large sample quantity, and decreased detection sensitivity. Micro-HPLC (pHPLC) is a term that encompasses a broad range of sample volumes and column sizes (as shown in Table 3.1), but Saito and coworkers provided narrower definitions in their review based on the size of the columns. ... 

Using amylose tris-3,5-dimethylphenylcarbamate as the chiral selector in enantioselective high-performance liquid chromatography, micropreparative resolution of the DHA racemate was achieved and the chromatographic behaviour in enantio-GC could be defined by coinjecting these references of definite chirality (Fig. 17.4) [13]. 

The availability of stable isotope-labeled PA makes an accurate quantitative determination of this imino acid possible. A short high-performance liquid chromatography (HPLC) run prior to the mass spectrometer inlet will result in a discrete peak of PA. For the definitive diagnosis of AASA dehydrogenase deficiency, a simultaneous determination of AASA would be preferred. The absence of a commercially available labeled standard leaves this analysis in the experimental stage. 

Studies in the area of chemical definition of starting materials began more than 10 years ago (23). In addition to wet chemistry, the laboratory measurements currently used for this purpose are differential scanning calorimetry (DSC), high-performance liquid chromatography (HPLC), gel permeation chromatography (GPC), infrared spectroscopy (IR), and rheology. 

High-performance liquid chrottHtogtaphy (HPLC), definition. 3 HlUC, 217-223 HPLC, definition, 3 Hydrodynamic chromatography, 142 Hydrolytic stability, 107,346,369-370 Hydrophilic interaction (HlUC), 5,135,136, 217-223... 

Before we delve into the details, let us spend a moment to define high-performance liquid chromatography. Chromatography in general comprises all separation techniques in which analytes partition between different phases that move relative to each other or where the analytes have different migration velocities. The latter part of the definition ineludes chromatographic techniques in which the analytes are transported via a field, such as in electrokinetic chromatography. 

A typical high-performance liquid chromatography (HPLC) system consists of two pumps, a mixer, an injector, a guard colunm, a separation column, a detector, an electrospray nozzle, and a mass spectrometer. The two pumps and the mixer allow establishment of desired solvent gradients. The injector is used to inject a small amount of sample into the column. In all separation techniques, definition of a small volume of injected sample is cmcial in preventing adverse broadening of peaks and a consequent loss in compmient resolution. The injected compounds are separated in the separation colunm and then detected via a simple detector or a mass spectrometer. All of the parts of the HPLC system have been miniaturized, and several research groups have been able to demonstrate on-chip HPLC separations. 

In conventional high-performance liquid chromatography (HPLC), columns are usually of 10-25 cm length and 2—4 mm i.d. Recently, capillary HPLC columns have become available in the market. The terminology, abbreviations, and definitions have not yet been standardized. In the literature, we can find microbore, micro-LC, semimicro-LC,... 

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