Mobile phase, high-performance liquid chromatography

WH Schaefer, F Dixon Jr. Effect of high-performance liquid chromatography mobile phase components on sensitivity in negative atmospheric pressure chemical ionization liquid chromatography-mass spectrometry. J Am Soc Mass Spectrom 7 1059—1069,1996. 

Schaefer, W.H. Dixon, F. Jr. Effect of High-Performance Liquid Chromatography Mobile Phase Components on Sensitivity in Negative Atmospheric Pressure Chemical Ionization Liquid Chromatography-Mass Spectrometry, J. Am. Soc. Mass Spectrom. 7, 1059-1069 (1996). 

Jemal, M. Hawthorn, D. J. Effect of high performance liquid chromatography mobile phase (methanol versus acetonitrile) on the positive and negative ion electrospray response of a compound that contains both... 

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. 

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. 

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. 

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. 

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... 

Procedure Flavonoids are then further purified with 2 ml of methanolic HC1 (2 N), followed by centrifugation (2 min, 15 600 g), hydrolyzation of 150 il of suspension in an autoclave (15 min, 120 C). A reverse osmosis-Millipore UF Plus water purification system is used in high performance liquid chromatography (HPLC) with an autosampler. After injections of 5 pg of samples, the mobile phases flow at a rate of 1 ml/minute with isocratic elution in a column at 30 C. 

If the flow of mobile phase is monitored by a detector and recorder/VDU system, such as is used in gas and high-performance liquid chromatography, then /R can be used as a measure of VR. 

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