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Josep Esteve-romero - One of the best experts on this subject based on the ideXlab platform.

  • An assay to determine rivaroxaban in pharmaceutical formulations by Micellar Liquid Chromatography
    Journal of the Iranian Chemical Society, 2020
    Co-Authors: Jaume Albiol-chiva, Juan Peris-vicente, Devasish Bose, Abhilasha Durgbanshi, Daniel García-ferrer, Pooja Mishra, Priyanka Padhey, Josep Esteve-romero
    Abstract:

    Rivaroxaban is one of the most prescribed anticoagulants. The ingestion of the correct dosage is a key to the success of the therapy. A procedure to evaluate the content of active principle ingredient in rivaroxaban pharmaceutical formulations, based on Micellar Liquid Chromatography, has been developed. Tablets were solved in the mobile phase and directly injected, thus avoiding the use of large volumes of organic solvents. Analysis was performed using a C18 column and a mobile phase containing 0.05 M sodium dodecyl sulfate—12.5% 1-propanol, buffered at pH 7 with phosphate salt, running under isocratic mode at 1 mL/min. The analyte was resolved in less than 6.0 min. Detection was by UV absorption at 250 nm. The method was successfully validated by the guidelines of the International Conference of Harmonization in terms of specificity, calibration range (0.01–1.00 mg/L), linearity, limit of detection (0.002 mg/L), limit of quantification (0.006 mg/L), trueness (99.6–99.7%), precision (

  • Determination of diuron, terbuthylazine, and terbutryn in wastewater and soil by Micellar Liquid Chromatography
    Analytical and Bioanalytical Chemistry, 2017
    Co-Authors: Susana Pitarch-andrés, Juan Peris-vicente, Pasqual Roca-genovés, Josep Esteve-romero
    Abstract:

    An analytical method for the quantification of the herbicides and algaecides diuron, terbuthylazine, and terbutryn in wastewater and soil by Micellar Liquid Chromatography was developed. The sample preparation was expedited to reduce the number of intermediate steps and the use of chemicals. The analytes in soils were recovered by ultrasonication in the mobile phase. The obtained supernatant and the water samples were directly injected, thus avoiding intermediate steps. The chromatographic behavior of the analytes, depending on the surfactant and alcohol was studied, in order to optimize the chromatographic run, by a chemometrical approach. The herbicides were resolved in

  • Determination of oxolinic acid, danofloxacin, ciprofloxacin, and enrofloxacin in porcine and bovine meat by Micellar Liquid Chromatography with fluorescence detection
    Food chemistry, 2016
    Co-Authors: David Terrado-campos, Samuel Carda-broch, Juan Peris-vicente, Khaled Tayeb-cherif, Josep Esteve-romero
    Abstract:

    A method was developed for the determination of oxolinic acid, danofloxacin, ciprofloxacin and enrofloxacin by Micellar Liquid Chromatography - fluorescence detection in commercial porcine and bovine meat. The samples were ultrasonicated in a Micellar solution, free of organic solvent, to extract the analytes, and the supernatant was directly injected. The quinolones were resolved in 0.9998), trueness (89.3-105.1%), precision (

  • A review on development of analytical methods to determine monitorable drugs in serum and urine by Micellar Liquid Chromatography using direct injection
    Analytica chimica acta, 2016
    Co-Authors: Josep Esteve-romero, Jaume Albiol-chiva, Juan Peris-vicente
    Abstract:

    Therapeutic drug monitoring is a common practice in clinical studies. It requires the quantification of drugs in biological fluids. Micellar Liquid Chromatography (MLC), a well-established branch of Reverse Phase-High Performance Liquid Chromatography (RP-HPLC), has been proven by many researchers as a useful tool for the analysis of these matrices. This review presents several analytical methods, taken from the literature, devoted to the determination of several monitorable drugs in serum and urine by Micellar Liquid Chromatography. The studied groups are: anticonvulsants, antiarrhythmics, tricyclic antidepressants, selective serotonin reuptake inhibitors, analgesics and bronchodilators. We detail the optimization strategy of the sample preparation and the main chromatographic conditions, such as the type of column, mobile phase composition (surfactant, organic solvent and pH), and detection. The finally selected experimental parameters, the validation, and some applications have also been described. In addition, their performances and advantages have been discussed. The main ones were the possibility of direct injection, and the efficient chromatographic elution, in spite of the complexity of the biological fluids. For each substance, the measured concentrations were accurate and precise at their respective therapeutic range. It was found that the MLC-procedures are fast, simple, inexpensive, ecofriendly, safe, selective, enough sensitive and reliable. Therefore, they represent an excellent alternative for the determination of drugs in serum and urine for monitoring purposes.

  • Advances on melamine determination by Micellar Liquid Chromatography: A review
    Journal of Liquid Chromatography & Related Technologies, 2016
    Co-Authors: Juan Peris-vicente, Pasqual Roca-genovés, Jaume Albiol-chiva, Josep Esteve-romero
    Abstract:

    ABSTRACTMelamine is a toxic triazine which has been recently proven as a threat to human health. It can be ingested by several methods, being the most important the unethical adulteration of protein-rich foodstuff for economic reasons. This review presents several analytical methods, taken from the literature studies, devoted to the determination of melamine in milk, dietetic supplements, drinking and wastewater, swine kidney, plasma, and urine, using Micellar Liquid Chromatography (MLC). We consider that the control of these samples is crucial to prevent and manage melamine intoxication. This technique has been demonstrated as an excellent tool to determine organic compounds in these matrices. We detail the optimization strategy and the obtained results in the different steps of method development, such as sample pretreatment, chromatographic separation, and validation process. The similarities and differences of the procedures have been described and discussed, as well as their advantages. The main ones...

Juan Peris-vicente - One of the best experts on this subject based on the ideXlab platform.

  • An assay to determine rivaroxaban in pharmaceutical formulations by Micellar Liquid Chromatography
    Journal of the Iranian Chemical Society, 2020
    Co-Authors: Jaume Albiol-chiva, Juan Peris-vicente, Devasish Bose, Abhilasha Durgbanshi, Daniel García-ferrer, Pooja Mishra, Priyanka Padhey, Josep Esteve-romero
    Abstract:

    Rivaroxaban is one of the most prescribed anticoagulants. The ingestion of the correct dosage is a key to the success of the therapy. A procedure to evaluate the content of active principle ingredient in rivaroxaban pharmaceutical formulations, based on Micellar Liquid Chromatography, has been developed. Tablets were solved in the mobile phase and directly injected, thus avoiding the use of large volumes of organic solvents. Analysis was performed using a C18 column and a mobile phase containing 0.05 M sodium dodecyl sulfate—12.5% 1-propanol, buffered at pH 7 with phosphate salt, running under isocratic mode at 1 mL/min. The analyte was resolved in less than 6.0 min. Detection was by UV absorption at 250 nm. The method was successfully validated by the guidelines of the International Conference of Harmonization in terms of specificity, calibration range (0.01–1.00 mg/L), linearity, limit of detection (0.002 mg/L), limit of quantification (0.006 mg/L), trueness (99.6–99.7%), precision (

  • Determination of diuron, terbuthylazine, and terbutryn in wastewater and soil by Micellar Liquid Chromatography
    Analytical and Bioanalytical Chemistry, 2017
    Co-Authors: Susana Pitarch-andrés, Juan Peris-vicente, Pasqual Roca-genovés, Josep Esteve-romero
    Abstract:

    An analytical method for the quantification of the herbicides and algaecides diuron, terbuthylazine, and terbutryn in wastewater and soil by Micellar Liquid Chromatography was developed. The sample preparation was expedited to reduce the number of intermediate steps and the use of chemicals. The analytes in soils were recovered by ultrasonication in the mobile phase. The obtained supernatant and the water samples were directly injected, thus avoiding intermediate steps. The chromatographic behavior of the analytes, depending on the surfactant and alcohol was studied, in order to optimize the chromatographic run, by a chemometrical approach. The herbicides were resolved in

  • Determination of oxolinic acid, danofloxacin, ciprofloxacin, and enrofloxacin in porcine and bovine meat by Micellar Liquid Chromatography with fluorescence detection
    Food chemistry, 2016
    Co-Authors: David Terrado-campos, Samuel Carda-broch, Juan Peris-vicente, Khaled Tayeb-cherif, Josep Esteve-romero
    Abstract:

    A method was developed for the determination of oxolinic acid, danofloxacin, ciprofloxacin and enrofloxacin by Micellar Liquid Chromatography - fluorescence detection in commercial porcine and bovine meat. The samples were ultrasonicated in a Micellar solution, free of organic solvent, to extract the analytes, and the supernatant was directly injected. The quinolones were resolved in 0.9998), trueness (89.3-105.1%), precision (

  • A review on development of analytical methods to determine monitorable drugs in serum and urine by Micellar Liquid Chromatography using direct injection
    Analytica chimica acta, 2016
    Co-Authors: Josep Esteve-romero, Jaume Albiol-chiva, Juan Peris-vicente
    Abstract:

    Therapeutic drug monitoring is a common practice in clinical studies. It requires the quantification of drugs in biological fluids. Micellar Liquid Chromatography (MLC), a well-established branch of Reverse Phase-High Performance Liquid Chromatography (RP-HPLC), has been proven by many researchers as a useful tool for the analysis of these matrices. This review presents several analytical methods, taken from the literature, devoted to the determination of several monitorable drugs in serum and urine by Micellar Liquid Chromatography. The studied groups are: anticonvulsants, antiarrhythmics, tricyclic antidepressants, selective serotonin reuptake inhibitors, analgesics and bronchodilators. We detail the optimization strategy of the sample preparation and the main chromatographic conditions, such as the type of column, mobile phase composition (surfactant, organic solvent and pH), and detection. The finally selected experimental parameters, the validation, and some applications have also been described. In addition, their performances and advantages have been discussed. The main ones were the possibility of direct injection, and the efficient chromatographic elution, in spite of the complexity of the biological fluids. For each substance, the measured concentrations were accurate and precise at their respective therapeutic range. It was found that the MLC-procedures are fast, simple, inexpensive, ecofriendly, safe, selective, enough sensitive and reliable. Therefore, they represent an excellent alternative for the determination of drugs in serum and urine for monitoring purposes.

  • Advances on melamine determination by Micellar Liquid Chromatography: A review
    Journal of Liquid Chromatography & Related Technologies, 2016
    Co-Authors: Juan Peris-vicente, Pasqual Roca-genovés, Jaume Albiol-chiva, Josep Esteve-romero
    Abstract:

    ABSTRACTMelamine is a toxic triazine which has been recently proven as a threat to human health. It can be ingested by several methods, being the most important the unethical adulteration of protein-rich foodstuff for economic reasons. This review presents several analytical methods, taken from the literature studies, devoted to the determination of melamine in milk, dietetic supplements, drinking and wastewater, swine kidney, plasma, and urine, using Micellar Liquid Chromatography (MLC). We consider that the control of these samples is crucial to prevent and manage melamine intoxication. This technique has been demonstrated as an excellent tool to determine organic compounds in these matrices. We detail the optimization strategy and the obtained results in the different steps of method development, such as sample pretreatment, chromatographic separation, and validation process. The similarities and differences of the procedures have been described and discussed, as well as their advantages. The main ones...

Samuel Carda-broch - One of the best experts on this subject based on the ideXlab platform.

  • Determination of oxolinic acid, danofloxacin, ciprofloxacin, and enrofloxacin in porcine and bovine meat by Micellar Liquid Chromatography with fluorescence detection
    Food chemistry, 2016
    Co-Authors: David Terrado-campos, Samuel Carda-broch, Juan Peris-vicente, Khaled Tayeb-cherif, Josep Esteve-romero
    Abstract:

    A method was developed for the determination of oxolinic acid, danofloxacin, ciprofloxacin and enrofloxacin by Micellar Liquid Chromatography - fluorescence detection in commercial porcine and bovine meat. The samples were ultrasonicated in a Micellar solution, free of organic solvent, to extract the analytes, and the supernatant was directly injected. The quinolones were resolved in 0.9998), trueness (89.3-105.1%), precision (

  • Analytical Separation Science - Micellar Liquid Chromatography: Fundamentals
    Analytical Separation Science, 2015
    Co-Authors: María Celia García-alvarez-coque, Maria Jose Ruiz-angel, Samuel Carda-broch
    Abstract:

    The reversed phase Liquid Chromatography (RPLC) mode with surfactant above the critical Micellar concentration (CMC) has been called Micellar Liquid Chromatography (MLC). In pure Micellar systems, the retention behavior is explained by considering three phases or environments: surfactant-modified stationary phase, bulk aqueous solvent, and Micellar pseudo-phase. Surfactant adsorption on the porous RPLC packing affects chromatographic retention, owing to the change of diverse surface properties of the stationary phase. In pure Micellar systems, the retention behavior is explained by considering three phases or environments: surfactant-modified stationary phase, bulk aqueous solvent, and Micellar pseudo-phase. In pure Micellar mobile phases, water-insoluble nonpolar solutes or species strongly bound to surfactant monomers do not participate significantly in the aqueous environment of the three-phase partitioning scheme. Some of the solutions proposed along the years to overcome these limitations have favored the potential of the technique, but they have not resulted in an extensive use. Keywords: bulk aqueous solvent; Micellar Liquid Chromatography; micelle breakdown; retention behavior; reversed phase Liquid Chromatography; surfactant-modified stationary phase

  • Analysis of danofloxacin, difloxacin, ciprofloxacin and sarafloxacin in honey using Micellar Liquid Chromatography and validation according to the 2002/657/EC decision
    Analytical Methods, 2015
    Co-Authors: K. Tayeb Cherif, Samuel Carda-broch, Juan Peris-vicente, Josep Esteve-romero
    Abstract:

    A reliable and sensitive method based on Micellar Liquid Chromatography was optimized for the analysis of fluoroquinolones danofloxacin, difloxacin, ciprofloxacin and sarafloxacin in honey.

  • Use of Micellar Liquid Chromatography to analyze darunavir, ritonavir, emtricitabine, and tenofovir in plasma.
    Journal of separation science, 2014
    Co-Authors: Juan Peris-vicente, Samuel Carda-broch, Inmaculada Casas-breva, Mónica Villarreal-traver, Josep Esteve-romero
    Abstract:

    Danuravir, ritonavir, emtricitabine, and tenofovir are together prescribed against AIDS as a highly active antiretroviral therapy regimen. Micellar Liquid Chromatography has been applied to determine these four antiretroviral drugs in plasma. The sample preparation is shortened to the dilution of the sample in a Micellar solution, filtration, and injection. Clean-up steps are avoided, due to the solubilization of plasma matrix in Micellar media. The drugs were analyzed in 0.995), accuracy (89.3–103.2%), precision (

  • A Micellar Liquid Chromatography method for the quantification of abacavir, lamivudine and raltegravir in plasma.
    Journal of pharmaceutical and biomedical analysis, 2014
    Co-Authors: Juan Peris-vicente, Samuel Carda-broch, Inmaculada Casas-breva, Mónica Villareal-traver, Josep Esteve-romero
    Abstract:

    Abstract An analytical methodology based on Micellar Liquid Chromatography has been developed to quantify abacavir, lamivudine and raltegravir in plasma. These three antiretroviral drugs are prescribed as a set in highly active antiretroviral therapy to acquired immunodeficiency syndrome patients. The experimental procedure consists in the dilution of the sample in Micellar media, followed by filtration and, without cleanup step. The analytes were resolved in less than 30 min using a mobile phase of 0.05 M sodium dodecyl sulphate at pH 7, running at 1 mL min−1 under isocratic mode at room temperature through a C18 column (125 × 4.6 mm, 5 μm particle size). The UV detection wavelength was set at 260 nm. The method was successfully validated following the requirements of ICH guidelines in terms of: linear range (0.25–2.5 μg mL−1), linearity (r2 > 0.990), intra- and interday precision (

María Celia García-alvarez-coque - One of the best experts on this subject based on the ideXlab platform.

  • Analytical Separation Science - Micellar Liquid Chromatography: Fundamentals
    Analytical Separation Science, 2015
    Co-Authors: María Celia García-alvarez-coque, Maria Jose Ruiz-angel, Samuel Carda-broch
    Abstract:

    The reversed phase Liquid Chromatography (RPLC) mode with surfactant above the critical Micellar concentration (CMC) has been called Micellar Liquid Chromatography (MLC). In pure Micellar systems, the retention behavior is explained by considering three phases or environments: surfactant-modified stationary phase, bulk aqueous solvent, and Micellar pseudo-phase. Surfactant adsorption on the porous RPLC packing affects chromatographic retention, owing to the change of diverse surface properties of the stationary phase. In pure Micellar systems, the retention behavior is explained by considering three phases or environments: surfactant-modified stationary phase, bulk aqueous solvent, and Micellar pseudo-phase. In pure Micellar mobile phases, water-insoluble nonpolar solutes or species strongly bound to surfactant monomers do not participate significantly in the aqueous environment of the three-phase partitioning scheme. Some of the solutions proposed along the years to overcome these limitations have favored the potential of the technique, but they have not resulted in an extensive use. Keywords: bulk aqueous solvent; Micellar Liquid Chromatography; micelle breakdown; retention behavior; reversed phase Liquid Chromatography; surfactant-modified stationary phase

  • Isocratic and gradient elution in Micellar Liquid Chromatography with Brij‐35
    Journal of separation science, 2015
    Co-Authors: E. Peris-garcía, C. Ortiz-bolsico, Juan José Baeza-baeza, María Celia García-alvarez-coque
    Abstract:

    Polyoxyethylene(23)lauryl ether (known as Brij-35) is a nonionic surfactant, which has been considered as an alternative to the extensively used in Micellar Liquid Chromatography anionic surfactant sodium lauryl (dodecyl) sulfate, for the analysis of drugs and other types of compounds. Brij-35 is the most suitable nonionic surfactant for Micellar Liquid Chromatography, owing to its commercial availability, low cost, low toxicity, high cloud temperature, and low background absorbance. However, it has had minor use. In this work, we gather and discuss some results obtained in our laboratory with several β-blockers, sulfonamides, and flavonoids, concerning the use of Brij-35 as mobile phase modifier in the isocratic and gradient modes. The chromatographic performance for purely Micellar eluents (with only surfactant) and hybrid eluents (with surfactant and acetonitrile) is compared. Brij-35 increases the polarity of the alkyl-bonded stationary phase and its polyoxyethylene chain with the hydroxyl end group allows hydrogen-bond interactions, especially for phenolic compounds. This offers the possibility of using aqueous solutions of Brij-35 as mobile phases with sufficiently short retention times. The use of gradients of acetonitrile to keep the concentration of Brij-35 constant is another interesting strategy that yields a significant reduction in the peak widths, which guarantee high resolution.

  • Retention mechanisms in Micellar Liquid Chromatography
    Journal of chromatography. A, 2008
    Co-Authors: Maria Jose Ruiz-angel, Samuel Carda-broch, J.r. Torres-lapasió, María Celia García-alvarez-coque
    Abstract:

    Micellar Liquid Chromatography (MLC) is a reversed-phase Liquid chromatographic (RPLC) mode with mobile phases containing a surfactant (ionic or non-ionic) above its critical Micellar concentration (CMC). In these conditions, the stationary phase is modified with an approximately constant amount of surfactant monomers, and the solubilising capability of the mobile phase is altered by the presence of micelles, giving rise to diverse interactions (hydrophobic, ionic and steric) with major implications in retention and selectivity. From its beginnings in 1980, the technique has evolved up to becoming a real alternative in some instances (and a complement in others) to classical RPLC with hydro-organic mixtures, owing to its peculiar features and unique advantages. This review is aimed to describe the retention mechanisms (i.e. solute interactions with both stationary and mobile phases) in an MLC system, revealed in diverse reports where the retention behaviour of solutes of different nature (ionic or neutral exhibiting a wide range of polarities) has been studied in a variety of conditions (with ionic and non-ionic surfactants, added salt and organic solvent, and varying pH). The theory is supported by several mechanistic models that describe satisfactorily the retention behaviour, and allow the measurement of the strength of solute-stationary phase and solute-micelle interactions. Suppression of silanol activity, steric effects in the packing pores, anti-binding behaviour, retention of ionisable compounds, compensating effect on polarity differences among solutes, and the contribution of the solvation parameter model to elucidate the interactions in MLC, are commented.

  • Micellar Liquid Chromatography: suitable technique for screening analysis.
    Journal of chromatography. A, 2002
    Co-Authors: Maria Jose Ruiz-angel, R. D. Caballero, Ernesto F. Simó-alfonso, María Celia García-alvarez-coque
    Abstract:

    The screening capability of Micellar Liquid Chromatography (MLC) is discussed using the reported chromatographic data of several sets of compounds (amino acids, beta-blockers, diuretics, phenethylamines, phenols, polynuclear aromatic hydrocarbons, steroids and sulfonamides) and new results (sulfonamides and steroids). The chromatographic data are treated with an interpretive optimisation resolution procedure to obtain the best separation conditions. Usually, the pH and the concentration of surfactant (sodium dodecyl sulfate, SDS, or cetyltrimethylammonium bromide) for the optimal mobile phase were 2.5-3 and 3, such as the steroids. For basic drugs such as the phenethylamines (0 < log P(o/w) < 1.7), eluted with a Micellar eluent of anionic SDS, propanol was too weak. A study is also shown for mixtures of sulfonamides (log P(o/w) = -1.2 to 1.7) and steroids (log P(o/w) = 3.0-8.1) eluted from conventional C18 columns with SDS mobile phases containing acetonitrile and 1-pentanol, respectively, which are compared with classical acetonitrile-water and methanol-water mixtures. The results complement a previous study on beta-blockers (log P(o/w) = -0.03 to 2.8) and reveal that MLC is a very competitive technique for the screening of compounds against conventional RPLC, due to its peculiar behaviour with regard to the selectivity and elution strength. The concentration of organic solvent needed to obtain sufficiently low retention times (even for highly hydrophobic steroids with log P(o/w) = 7-8) is also appreciably smaller for MLC, which reduces the environmental impact of the mobile phases.

  • Quantitative structure–retention and retention–activity relationships of β-blocking agents by Micellar Liquid Chromatography
    Journal of chromatography. A, 2001
    Co-Authors: A Detroyer, María Celia García-alvarez-coque, Samuel Carda-broch, Y. Vander Heyden, D.l. Massart
    Abstract:

    Abstract Sixteen β-blocking agents (acebutolol, alprenolol, atenolol, bisoprolol, carteolol, celiprolol, esmolol, labetalol, metoprolol, nadolol, oxprenolol, pindolol, practolol, propranolol, sotalol and timolol) showing a large range of hydrophobicity (octanol–water partition coefficients, log P between −0.026 and 2.81) were subjected to Micellar Liquid Chromatography with sodium dodecyl sulfate as micelle forming agent, and n-propanol as organic modifier. The correlation between log P and the retention factor extrapolated to a mobile phase free of micelles and organic modifier was investigated. The use of an interpolated retention factor or the retention factor for specific individual experimental mobile phases was however advantageous since the retention factors of all β-blocking agents were measurable in the selected mobile phases. Good correlations with log P and with in vitro biological parameters (cellular permeability coefficients in Caco-2 monolayers and apparent permeability coefficients in rat intestinal segments) were found.

María Luisa Marina - One of the best experts on this subject based on the ideXlab platform.

  • Evaluation of distribution coefficients in Micellar Liquid Chromatography
    Journal of Chromatography A, 1997
    Co-Authors: María Luisa Marina, M.a. García
    Abstract:

    The possibilities of Micellar Liquid Chromatography for evaluating distribution coefficients are discussed. Determination of solute-micelle association constants and distribution coefficients of solutes between stationary-aqueous, stationary-Micellar and aqueous-Micellar phases is described. Application of the calculation of distribution coefficients to the study of the retention mechanism of solutes in the chromatographic system and prediction of separation selectivity is also presented.

  • A model describing the effect on retention of the addition of alcohols to the mobile phase in Micellar Liquid Chromatography
    Journal of Chromatography A, 1996
    Co-Authors: O. Jiménez, M.a. García, María Luisa Marina
    Abstract:

    A physico-chemical model relating the capacity factor of a solute to micellized surfactant and organic modifier concentrations in Micellar Liquid Chromatography with hybrid eluents is proposed. The equation derived from this model and some simplified equations were tested by using retention data in Micellar mobile phases containing hexadecyltrimethylammonium bromide and sodium dodecyl sulphate as surfactants and n-propanol and n-butanol as organic modifiers. Good agreement between calculated and experimental capacity factors was found and the use of this model to predict the retention behaviour of solutes in Micellar Liquid Chromatography is proposed.

  • Prediction and Modelling Studies for Capacity Factors of a Group of Dihydropyridines in Micellar Liquid Chromatography with Hybrid Eluents
    Journal of Liquid Chromatography & Related Technologies, 1996
    Co-Authors: O. Jiménez, I. Benito, María Luisa Marina
    Abstract:

    Empirical equations were used to predict the retention behaviour of a group of twenty-seven dihydropyridines in Micellar Liquid Chromatography with hybrid eluents on an octylsilica column. A theoretical model was also used to study their retention mechanism. Hexadecyltrimethylammonium bromide and sodium dodecyl sulphate were used as surfactants in the mobile phase and as organic modifiers n-propanol and n-butanol were employed.

  • Study of the Separation Selectivity of a Group of Benzene and Naphthalene Derivatives in Micellar Liquid Chromatography
    Microchemical Journal, 1996
    Co-Authors: María Luisa Marina, M.a. García, O. Jiménez, S. Vera
    Abstract:

    The influence of the surfactant nature and concentration in the mobile phase on the separation selectivity of fifteen benzene and naphthalene derivatives in Micellar Liquid Chromatography has been determined by using an octadecylsilica column. Sodium dodecylsulphate (SDS), hexadecyltrimetylammonium bromide (CTAB) and polioxietilen[23] dodecanol (Brij-35) have been used at concentrations ranged from 0.02 M to 0.1 M. A multiple linear regression program has allowed to find an expression for the selectivity as a function of the two parameters studied (surfactant nature and concentration).

  • Retention mechanism and implications for selectivity for a group of dihydropyridines in ionic Micellar Liquid Chromatography
    Journal of chromatography. A, 1994
    Co-Authors: J.m. Saz, María Luisa Marina
    Abstract:

    The retention behaviour of a group of dihydropyridines in Micellar Liquid Chromatography was studied using sodium dodecyl sulphate and hexadecyltrimethylammonium bromide as surfactants in the mobile phase containing 5% of n-butanol and a C18 column. When the surfactant concentration in the mobile phase is increased, a tendency to change from a three partition equilibria mechanism to direct transfer of solutes from micelles to the stationary phase is observed for both surfactants. This progressive change in the retention mechanism is explained through the large Micellar phase-water partition coefficients of these compounds and the increase produced in the fraction of solute molecules in the Micellar phase due to the increase in the volume of this phase originating from the increase in surfactant concentration. As a result, the selectivity coefficients show a tendency to match the ratio of the stationary phase to Micellar phase partition coefficients of these compounds, constituting further proof of the progressive change in the retention mechanism when the surfactant concentration is increased.