Reverse phase - high performance liquid chromatography RP-HPLC

The aim of the work is investigate possibilities of application of Cartridges Packed DIAPAK for concentrating antibiotics Cefazoline and Levomycetine and analyze them by Reversed Phase High Performance Liquid Chromatography (RP HPLC). 

Lipophilicity represents the affinity of a molecule or a moiety for a lipophilic environment. It is commonly measured by its distribuHon behaviour in a biphasic system, either liquid-liquid (e.g. partition coefficient in 1-octanol/water) or solid-liquid (retention on reversed-phase high-performance liquid chromatography (RP-HPLC) or thin-layer chromatography (TLC) system). 

Reversed-phase high-performance liquid chromatography (RP-HPLC), cholesterol measurement, 456-458 Rhamnogalacturonanas, 735 Rice bran oil, tocopherols/tocotrienols in, 488 (figs.)... 

I de Noni, G de Bernardi, L Pellegrino. Detection of common-wheat (Triticum aestivum) flour in Durum-wheat (Triticum durum) semolina by reverse-phase high-performance liquid chromatography (RP-HPLC) of specific albumins. Food Chem 51 325-329, 1994. 

An aldehyde was mixed with solid supported triphenylphosphine oxide (3 equiv.), alkyl halide (4 equiv.), and potassium carbonate (4 equiv.) in methanol (2 ml). The mixture was heated at 150° for 5 min. The residue was filtered through a short plug of silica gel and washed. The solution was concentrated and purified by reverse-phase high-performance liquid chromatography (RP-HPLC). 

Synthetic peptides often lack the conformational stability required for a successful drug therefore determination of peptide stability in serum constitutes a powerful and important screening assay for the elimination of unstable peptides in the pipeline of drug development (see Note 1). Peptide stability in serum can rather easily be determined by reverse phase-high-performance liquid chromatography (RP-HPLC) and mass spectroscopy (MS) from both in vitro and in vivo studies. 

Reversed-phase high performance liquid chromatography (RP HPLC) works by eluates partitioning between mobile and stationary phases, and the retention factor log k is proportional to log Kow. Numerous studies have correlated Koc with log k, and Gawlik et al. (1997) list 35 such correlations, most of which relate to specific chemical classes. Note that the correlations vary with the stationary phase used. Some examples are ... 

Equipment and expertise. Synthesis requires dedicated laboratory space and equipment. Protein synthesis is best done with the aid of a peptide synthesizer which is capable of optimal step-wise yields. Purification using reverse-phase high-performance liquid chromatography (RP-HPLC) is an integral part of the procedure (16), so at least one preparative and one analytical HPLC systems is needed. Access to electrospray mass spectrometry is essential. 

The use of cyclodextrins as the mobile phase components which impart stereoselectivity to reversed phase high performance liquid chromatography (RP-HPLC) systems are surveyed. The exemplary separations of structural and geometrical isomers are presented as well as the resolution of some enantiomeric compounds. A simplified scheme of the separation process occurring in RP-HPLC system modified by cyclodextrin is discussed and equations which relate the capacity factors of solutes to cyclodextrin concentration are given. The results are considered in the light of two phenomena influencing separation processes adsorption of inclusion complexes on stationary phase and complexation of solutes in the bulk mobile phase solution. 

Reversed-phase high-performance liquid chromatography (RP-HPLC) is the usual method of choice for the separation of anthocyanins combined with an ultraviolet-visible (UV-Vis) or diode-array detector (DAD)(Hebrero et al., 1988 Hong et ah, 1990). With reversed-phase columns the elution pattern of anthocyanins is mainly dependent on the partition coefficients between the mobile phase and the Cjg stationary phase, and on the polarity of the analytes. The mobile phase consists normally of an aqueous solvent (water/carboxylic acid) and an organic solvent (methanol or acetonitrile/carboxylic acid). Typically the amount of carboxylic acid has been up to 10%, but with the addition of a mass spectrometer as a detector, the amount of acid has been decreased to as low as 1 % with a shift from trifluoroacetic acid to formic acid to prevent quenching of the ionization process that may occur with trifluoroacetic acid. The acidic media allows for the complete displacement of the equilibrium to the fiavylium cation, resulting in better resolution and a characteristic absorbance between 515 and 540 nm. HPLC separation methods, combined with electrochemical or DAD, are effective tools for anthocyanin analysis. The weakness of these detection methods is a lack of structural information and some nonspecificity leading to misattribution of peaks, particularly with electrochemical... 

WS The water solubility was estimated by Kurz [296] from the relationship of WS and the retention time of test chemicals in reverse-phase high-performance liquid chromatography (RP-HPLC method). 

The stable nonvolatile intermediate phenylthiocar-bamoyl derivatives are formed in basic media and can be analyzed directly by reverse-phase high-performance liquid chromatography (RP-HPLC). Their cyclization into hydantoins requires acid catalysis. This mode of derivatization is a very important supplement to the Edman s method of N-terminated sequencing of polypeptides. Before GC analysis, any hydantoins can be converted into N-trifluoroacetyl or enol-O-trimethylsilyl derivatives, which increases the selectivity of their determination in complex matrices. 

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