Physico-chemical modelling of solute retention in reversed-phase HPLC with methanol-water mobile phase

1989 ◽  
Vol 27 (11-12) ◽  
pp. 628-630 ◽  
Author(s):  
Teresa Kowalska
2011 ◽  
Vol 8 (1) ◽  
pp. 340-346 ◽  
Author(s):  
Rajesh M. Kashid ◽  
Santosh G. Singh ◽  
Shrawan Singh

A reversed phase HPLC method that allows the separation and simultaneous determination of the preservatives methyl paraben (M.P.) and propyl paraben (P.P.) is described. The separations were effected by using an initial mobile phase of water: acetonitrile (50:50) on Inertsil C18 to elute P.P. and M.P. The detector wavelength was set at 205 nm. Under these conditions, separation of the two components was achieved in less than 10 min. Analytical characteristics of the separation such as precision, specificity, linear range and reproducibility were evaluated. The developed method was applied for the determination of preservative M.P. and P.P. at concentration of 0.01 mg/mL and 0.1 mg/mL respectively. The method was successfully used for determining both compounds in sucralfate suspension.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Beata Polak ◽  
Adam Traczuk ◽  
Sylwia Misztal

AbstractThe problems with separation of amino acid mixtures in reversed-phase mode are the result of their hydrophilic nature. The derivatisation of the amino group of mentioned above solutes leads to their solution. For this purpose, 9-fluorenylmethoxycarbonyl chloroformate (f-moc-Cl) as the derivatisation reagent is often used. In our study, the separation of some f-moc- amino acid derivatives (alanine, phenylalanine, leucine, methionine, proline and tryptophan) with the use of micellar systems of reversed-phase high-performance thin-layer chromatography (HPTLC) and pressurized planar electrochromatography (PPEC) is investigated. The effect of surfactant concentration, its type (anionic, cationic and non-ionic) and mobile phase buffer pH on the discussed above solute migration distances are presented. Our work reveals that the increase of sodium dodecylsulphate concentration in the mobile phase has a different effect on solute retention in HPTLC and PPEC. Moreover, it also affects the order of solutes in both techniques. In PPEC, in contrast to the HPTLC technique, the mobile phase pH affects solute retention. The type of surfactant in the mobile phase also impacts solute retention and migration distances. A mobile phase containing SDS improves system efficiency in both techniques. Herein, such an effect is presented for the first time.


OENO One ◽  
2010 ◽  
Vol 44 (2) ◽  
pp. 117
Author(s):  
Dominique Salameh ◽  
Cédric Brandam ◽  
Toufic Rizk ◽  
Roger Lteif ◽  
Pierre Strehaiano

<p style="text-align: justify;"><strong>Aims</strong>: This paper presents a rapid chromatographic method to monitor the concentration of <em>p</em>-coumaric acid in wine and in bioconversion studies.</p><p style="text-align: justify;"><strong>Methods and results</strong>: RP-HPLC method was validated in synthetic wine medium and in natural red wine. Mobile phase composition was water 77%, acetonitrile 23%. Formic acid was added to control pH at 3.5. The flow was 0.7 mL/min and the temperature 30 °C. The detection was done using UV at 305 nm. The linearity range was validated between 0.5 and 15 mg/L. The resolution was respectively 5.35 and 2.99. The detection and quantification limits were 0.01 mg/L and 0.04 mg/L. This method was used to study <em>p</em>-coumaric acid bioconversion into 4-ethylphenol and 4-vinylphenol, and to study this acid adsorption in enological conditions.</p><p style="text-align: justify;"><strong>Conclusions</strong>: This paper presented a simple HPLC method to monitor the concentration of <em>p</em>-coumaric acid in synthetic media and natural wine. It was used to study the <em>p</em>-coumaric acid bioconversion rates and mechanism.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: This method is useful to monitor <em>p</em>-coumaric acid concentration, which helps to predict amounts of 4-ethylphenol or 4-vinylphenol that can be produced in wine. This method can be helpful to control undesirable phenolic flavors potential in wine.</p>


Author(s):  
Oleg Borisovich Rudakov ◽  
Liudmila V. Rudakova ◽  
Vladimir F. Selemenev

This article deals with acetonitrile physico-chemical properties and its mixtures with water. It covers the information about isotherms of such parameters of the acetonitrile-water binary system as density, viscosity, permeation coefficient, refraction index, optic density, a boiling point isobar. Authors suggest a generalized criterion of acetonitrile polarity. The article also discusses means of polarity assessment and eluotropic strength of mobile phases on the basis of acetonitrile mixtures with water with application of generalized criteria. Special attention is paid to the options of acetonitrile application in various extraction methods of chromatographic sample preparation. The article also reveals advantages and problems of acetonitrile application as a mobile phase modifying agent in the HPLC reversed-phase and as a hydrophilic extra-agent in liquid-liquid extraction.


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