Mobile phase, high-performance liquid

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. 

As a method of research, has been used high-performance liquid chromatography in reversed - phase regime (RP HPLC). The advantage of the present method is the following the additional information about AIST and FAS composition (homologous distribution) simple preparation of samples (dilution of a CS sample of in a mobile phase). 

Commercial grades of PVP, K-15, K-30, K-90, and K-120 and the quaternized copolymer of vinylpyrrolidone and dimthylaminoethylmethacrylate (poly-VP/ DMAEMA) made by International Specialty Products (ISP) were used in this study. PEO standard calibration kits were purchased from Polymer Laboratories Ltd. (PL), American Polymer Standards Corporation (APSC), Polymer Standards Service (PSS), and Tosoh Corporation (TSK). In addition, two narrow NIST standards, 1923 and 1924, were used to evaluate commercial PEO standards. Deionized, filtered water, and high-performance liquid chromatography grade methanol purchased from Aldrich or Fischer Scientific were used in this study. Lithium nitrate (LiN03) from Aldrich was the salt added to the mobile phases to control for polyelectrolyte effects. 

Y. Cui and S. V. Olesik, High-performance liquid cliromatography using mobile phases with enhanced fluidity . Anal. Chem. 63 1812-1819 (1991). 

High-performance liquid chromatography is in some respects more versatile than gas chromatography since (a) it is not limited to volatile and thermally stable samples, and (b) the choice of mobile and stationary phases is wider. 

This is not the case when high performance liquid chromatography (HPLC) and MS are considered where, due to the incompatibilities of the two techniques, they cannot be linked directly and an interface must be used, with its prime purpose being the removal of the chromatographic mobile phase. Unfortunately, no single... 

B. Waiczak, L. Morin-Allory, M. Chrdtien, M. Lafosse and M. Dreux, Factor analysis and experiment design in high-performance liquid chromatography. III. Influence of mobile phase modifications on the selectivity of chalcones on a diol stationary phase. Chemom. Intell. Lab. Syst., I (1986) 79-90. 

High-performance liquid chromatography (HPLC) with a micellar mobile phase or with a selective pre-column or reaction detection system has also been used to determine alkylenebis(dithiocarbamaes). ° Zineb and mancozeb residues in feed were determined by ion-pair HPLC with ultraviolet (UV) detection at 272 nm. These compounds were converted to water-soluble sodium salts with ethylenediaminetetra-acetic acid (EDTA) and sodium hydroxide. The extracts were ion-pair methylated with tetrabuthylammonium hydrogensulfate (ion-pair reagent) in a chloroform-hexane solvent mixture at pH 6.5-8.S. The use of an electrochemical detector has also been reported. ... 

Degasser for high-performance liquid chromatography (HPLC) mobile phase... 

Lee, S. T. and Olesik, S. V., Normal-phase high-performance liquid chromatography using enhanced fluidity liquid mobile phases, /. Chromatogr. A, 707, 217, 1995. 

Tscheme, R. J. and Umagat, H., Determination of isophenindamine in phen-indamine tartrate using an argentated high-performance liquid chromatographic mobile phase, /. Pharm. Sci., 69, 342, 1980. 

Kirkland, J. J., Henderson, J. W., DeStefano, J. J., van Straten, M. A., and Claessens, H. A., Stability of silica-based, endcapped columns with pH 7 and 11 mobile phase for reversed-phase high-performance liquid chromatography, J. Chromatogr., A, 762(1 2), 97, 1997. 

Mazsaroff, I., Bischoff, R., Tice, P. A., and Regnier, F. E., Influence of mobile phase pH on high-performance liquid chromatographic column loading capacity, /. Chromatogr., 437, 429, 1988. 

High Performance Liquid Chromatographic (HPLC) Analysis. A Waters HPLC system (two Waters 501 pumps, automated gradient controller, 712 WISP, and 745 Data module) with a Shimadzu RF-535 fluorescence detector or a Waters 484 UV detector, and a 0.5 pm filter and a Rainin 30 x 4.6 mm Spheri-5 RP-18 guard column followed by a Waters 30 x 3.9 cm (10 pm particle size) p-Bondapak C18 column was used. The mobile phase consisted of a 45% aqueous solution (composed of 0.25% triethylamine, 0.9% phosphoric acid, and 0.01% sodium octyl sulfate) and 55% methanol for prazosin analysis or 40% aqueous solution and 60% methanol for naltrexone. The flow rate was 1.0 mL/min. Prazosin was measured by a fluorescence detector at 384 nm after excitation at 340 nm (8) and in vitro release samples of naltrexone were analyzed by UV detection at 254 nm. 

Young, P.M., Wheat, T.E. (1990). Optimization of high-performance liquid chromatographic peptide separations with alternative mobile and stationary phases. J. Chromatogr. 512,273-281. 

Sternson et al. [58] used a high performance liquid chromatographic method for the analysis of miconazole in plasma. Miconazole was extracted from alkalinized plasma with n-heptane-isamyl alcohol (98.5 1.5) and separated by high performance performance liquid chromatography on p-Bondapak Ci8 with ultraviolet detection at 254 nm. The mobile phase was methanol-tetrahydrofuran-acetate buffer (pH 5) (62.5 5 32.5) containing 5 mmol octanesulfonate per liter. The flow rate was 2 mL/min. Recovery was 100%. The relative standard deviation for injection-to-injection reproducibility was 0.4% and that for sample-to-sample variation was 5% at high miconazole concentrations (30 pg/mL) and 1% at low (1 pg/mL) concentrations. The limit of detection was 250 ng/mL. 

Fan used a high performance liquid chromatographic method for the qualitative and quantitative analysis of miconazole [59], Miconazole sample was dissolved in methanol and determined by high performance liquid chromatography using methanol-water (75 25) as the mobile phase and ultraviolet detection at 214 nm, the recovery was more than 99.4% and the accuracy was satisfactory for the qualitative and quantitative analysis. 

Guillaume et al. [69] presented a high performance liquid chromatographic method for an association study of miconazole and other imidazole derivatives in surfactant micellar using a hydrophilic reagent, Montanox DF 80. The thermodynamic results obtained showed that imidazole association in the surfactant micelles was effective over a concentration of surfactant equal to 0.4 pM. In addition, an enthalpy-entropy compensation study revealed that the type of interaction between the solute and the RP-18 stationary phase was independent of the molecular structure. The thermodynamic variations observed were considered the result of equilibrium displacement between the solute and free ethanol (respectively free surfactant) and its clusters (respective to micelles) created in the mobile phase. 

Gagliardi et al. [72] developed a simple high performance liquid chromatographic method for the determination of miconazole and other antimycotics in cosmetic antidandruff formulations. This high performance liquid chromatographic method was carried out on a Discovery RP Amide Ci6 column and spectrophotometric detection was performed at 220 nm. The initial mobile phase was a mixture of acetonitrile and aqueous 0.001 M sodium perchlorate (pH 3) in the ratio of 15 85 (v/ v) then a linear gradient less than 46% acetonitrile in 70 min, and less than 50% in 80 min. The extraction procedure was validated by analyzing samples of shampoo... 

Aboul-Enein and Ali [78] compared the chiral resolution of miconazole and two other azole compounds by high performance liquid chromatography using normal-phase amylose chiral stationary phases. The resolution of the enantiomers of ( )-econazole, ( )-miconazole, and (i)-sulconazole was achieved on different normal-phase chiral amylose columns, Chiralpak AD, AS, and AR. The mobile phase used was hexane-isopropanol-diethylamine (400 99 1). The flow rates of the mobile phase used were 0.50 and 1 mL/min. The separation factor (a) values for the resolved enantiomers of econazole, miconazole, and sulconazole in the chiral phases were in the range 1.63-1.04 the resolution factors Rs values varied from 5.68 to 0.32. 

In this study, Ali and Aboul-Enein [80] used cellulose tr is (3,5-d ich Ioropheny 1 carbamate) chiral stationary phase for the enantioseparation of miconazole and other clinically used drugs by high performance liquid chromatography. The mobile... 

High performance liquid chromatography-mass spectrometric methods Nitin et al. [75] developed and validated a sensitive and selective liquid chromatography-tandem mass spectrometric method (LC MS MS) for the simultaneous estimation of bulaquine and its metabolites primaquine in monkey plasma. The mobile phase consisted of acetonitrile ammonium acetate buffer (20 mM, pH 6) (50 50, v/v) at a flow rate of 1 mL/min. The chromatographic separations were achieved on two Spheri cyano columns (5 pm, 30 cm x 4.6 mm), connected in... 

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