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Russo G, Kajtazi A, Vallaro M, Surmont P, Ermondi G, Anderson S, Grumetto L, Caron G, Lynen F. High-throughput and reliable assessments of the ionization constant of monoprotic organic acids through an arginine based mixed mode HPLC. J Pharm Biomed Anal 2023; 235:115604. [PMID: 37531733 DOI: 10.1016/j.jpba.2023.115604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 07/19/2023] [Accepted: 07/24/2023] [Indexed: 08/04/2023]
Abstract
The charge state of a molecule is the single most prominent attribute ruling out its interactions with the surrounding environment. In a previous study, the retention of acids on the new Celeris™ Arginine (ARG) column was found to be predominantly driven by electrostatics and, specifically, their charge state. Therefore, we analysed 41 compounds in liquid chromatography with ultraviolet detection to study possible relationships between the analytical retention on this phase and the pKa of the acidic solutes. Highly significant relationships were observed indicating either a linear (r2 = 0.86) or a quadratic (r2= 0.89) trend. To improve the throughput of the method, this was transferred to LC mass spectrometry, allowing the analysis of a molecule every 3 mins. The developed method was found to be fast, reliable, accurate, easily automatable and simple to set up. Finally, the analytical column's being industrially manufactured and commercially available offers broad applicability.
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Affiliation(s)
- Giacomo Russo
- School of Applied Sciences, Sighthill Campus, Edinburgh Napier University, 9 Sighthill Ct, EH11 4BN Edinburgh, United Kingdom.
| | - Ardiana Kajtazi
- Separation Science Group, Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4bis, B-9000 Ghent, Belgium
| | - Maura Vallaro
- CASSMedChem Research Group, Molecular Biotechnology and Health Sciences Department, University of Turin, piazza Nizza 44 bis 10126 Turin, Italy
| | - Pieter Surmont
- Separation Science Group, Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4bis, B-9000 Ghent, Belgium
| | - Giuseppe Ermondi
- CASSMedChem Research Group, Molecular Biotechnology and Health Sciences Department, University of Turin, piazza Nizza 44 bis 10126 Turin, Italy
| | - Scott Anderson
- Regis Technologies Inc., 8210 Austin Ave, Morton Grove, IL 60053, USA
| | - Lucia Grumetto
- Department of Pharmacy, School of Medicine and Surgery, University of Naples Federico II, Via D. Montesano, 49, I-80131 Naples, Italy
| | - Giulia Caron
- CASSMedChem Research Group, Molecular Biotechnology and Health Sciences Department, University of Turin, piazza Nizza 44 bis 10126 Turin, Italy
| | - Frédéric Lynen
- Separation Science Group, Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4bis, B-9000 Ghent, Belgium
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2
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Canbay HS. Spectrophotometric determination of acid dissociation constants of some arylpropionic acids and arylacetic acids in acetonitrile-water binary mixtures at 25ºC. BRAZ J PHARM SCI 2022. [DOI: 10.1590/s2175-97902022e20740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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3
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Morais Missina J, Conti L, Rossi P, Ienco A, Gioppo Nunes G, Valtancoli B, Chelazzi L, Paoli P. Ibuprofen as linker for calcium(II) in a 1D-coordination polymer: A solid state investigation complemented with solution studies. Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2021.120319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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4
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Reshetova EN. Adsorption of mandelic acid enantiomers on chiral stationary phase with grafted antibiotic eremomycin: The effect of the eluent pH. J LIQ CHROMATOGR R T 2020. [DOI: 10.1080/10826076.2020.1842212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Elena N. Reshetova
- Institute of Technical Chemistry of the Ural Branch, Russian Academy of Science, Perm, Russia
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5
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Gogolishvili OS, Reshetova EN. Chromatographic enantioseparation and adsorption thermodynamics of hydroxy acids and their derivatives on antibiotic-based chiral stationary phases as affected by eluent pH. Chromatographia 2020. [DOI: 10.1007/s10337-020-03978-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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6
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Çelebİer M, Nennİ M, Kaplan O, Akgeyİk E, Kaynak MS, Şahİn S. Determination of the Physicochemical Properties of Piroxicam. Turk J Pharm Sci 2020; 17:535-541. [PMID: 33177935 DOI: 10.4274/tjps.galenos.2019.82335] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 09/05/2019] [Indexed: 12/01/2022]
Abstract
Objectives The aim of this study was to determine the acid dissociation constant (pKa) of piroxicam using high performance liquid chromatography (HPLC) and ultraviolet-visible (UV-Vis) spectrophotometry, and to determine the partition coefficient (Log P), distribution coefficient (Log D), and "Log kw" values of piroxicam using HPLC. Materials and Methods The HPLC studies were performed on a reversed-phase ACE C18 (150x4.6 mm ID, 5 μm) column at a flow rate of 1.0 mL min-1. The detector was set to 360 nm. Log D at different pH values (3.0-6.5) was examined with a phosphate buffer (20 mM) and acetonitrile (30:70 v/v) mixture as the mobile phase. For pKa determination, HPLC studies were performed with a mixture of phosphate buffer (20 mM) and methanol within the pH range of 3.50-6.00. Log kw measurements were performed with phosphate buffer (20 mM) and MeOH (from 20:80 v/v to 10:90 v/v) mixtures within the pH range of 3.50-6.00. UV-Vis spectrophotometric pKa measurements were performed at 285 nm wavelength. Results The pKa value of piroxicam was found to be 5.3 by HPLC and 5.7 by UV-Vis spectrophotometry. Log P of piroxicam was determined as 1.58 in our experimental conditions. Log D values were 1.57, 1.57, 1.44, 1.13, and 0.46 for pH values of 3.17, 3.79, 4.44, 5.42, and 6.56, respectively. Conclusion In the literature, different Log P (3.1, 2.2, and 0.6) and pKa (6.3 and 4.8) values were reported for piroxicam. The Log P (1.58) and pKa (5.3 and 5.7) values obtained for piroxicam in our study were within the range of the literature values. All these results indicate that different experimental approaches used for the determination of physicochemical properties could provide different values. Although UV spectrophotometry is easy to apply, HPLC is a unique technique for simultaneous determination of pKa, Log D, and Log P values of compounds.
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Affiliation(s)
- Mustafa Çelebİer
- Hacettepe University Faculty of Pharmacy, Department of Analytical Chemistry, Ankara, Turkey
| | - Merve Nennİ
- Çukurova University Faculty of Pharmacy, Department of Analytical Chemistry, Adana, Turkey
| | - Ozan Kaplan
- Hacettepe University Faculty of Pharmacy, Department of Analytical Chemistry, Ankara, Turkey
| | - Emrah Akgeyİk
- İnönü University Faculty of Pharmacy, Department of Analytical Chemistry, Malatya, Turkey
| | - Mustafa Sinan Kaynak
- Anadolu University Yunus Emre Vocational School, Department of Pharmacy, Program in Pharmacy Services, Eskişehir, Turkey
| | - Selma Şahİn
- Hacettepe University Faculty of Pharmacy, Department of Pharmaceutical Technology, Ankara, Turkey
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Feehan JF, Monaghan J, Gill CG, Krogh ET. Direct Measurement of Acid Dissociation Constants of Trace Organic Compounds at Nanomolar Levels in Aqueous Solution by Condensed Phase-Membrane Introduction Mass Spectrometry. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2019; 38:1879-1889. [PMID: 31211442 DOI: 10.1002/etc.4519] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 02/28/2019] [Accepted: 06/12/2019] [Indexed: 06/09/2023]
Abstract
We report the use of condensed phase-membrane introduction mass spectrometry as a novel method for the determination of acid dissociation constants for hydrophobic organic acids in aqueous solution at nanomolar concentrations. The technique is based on the pH-dependent permeation of analytes through a semipermeable polydimethylsiloxane membrane probe that is immersed directly in aqueous samples. We describe the method and report the dissociation constant (pKa ) values for compounds of biological and environmental relevance, including contaminants, pharmaceuticals, and naphthenic acids. The approach can be applied to individual compounds, combined suites, and complex mixtures at parts-per-billion levels. We report pKa values for 10 carboxylic acids with precision estimates and relative errors (where reliable literature values are available) of <0.1 log units. We report acidity constants for 2-methyl-3-methoxy-4-phenyl butanoic acid (a biomarker for microcystin algal toxins) and 4-t-butylcyclohexane carboxylic acid (a model naphthenic acid) as 4.28 ± 0.03 and 5.15 ± 0.05, respectively. Furthermore, we employ this approach to measure the effect of both temperature and deuterium oxide (heavy water) on acid dissociation, reporting the enthalpy and entropy changes for the ionization of a representative carboxylic acid and substituted phenol. Environ Toxicol Chem 2019;38:1879-1889. © 2019 SETAC.
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Affiliation(s)
- Jackelyn F Feehan
- Applied Environmental Research Laboratories, Department of Chemistry, Vancouver Island University, Nanaimo, British Columbia, Canada
| | - Joseph Monaghan
- Applied Environmental Research Laboratories, Department of Chemistry, Vancouver Island University, Nanaimo, British Columbia, Canada
| | - Chris G Gill
- Applied Environmental Research Laboratories, Department of Chemistry, Vancouver Island University, Nanaimo, British Columbia, Canada
- Department of Chemistry, University of Victoria, Victoria, British Columbia, Canada
| | - Erik T Krogh
- Applied Environmental Research Laboratories, Department of Chemistry, Vancouver Island University, Nanaimo, British Columbia, Canada
- Department of Chemistry, University of Victoria, Victoria, British Columbia, Canada
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Reshetova EN, Asnin LD, Kachmarsky K. Effect of Secondary Equilibria on the Adsorption of Ibuprofen Enantiomers on a Chiral Stationary Phase with a Grafted Antibiotic Eremomycin. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2018. [DOI: 10.1134/s0036024418010223] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Savić J, Marković B, Vitnik V, Dilber S. Determination of ionization constants (PKA) of β-hydroxy-β-arylalkanoic acids using high-pressure liquid chromatography. KRAGUJEVAC JOURNAL OF SCIENCE 2018. [DOI: 10.5937/kgjsci1840103s] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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10
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Reshetova EN. Effect of the ionic strength of a mobile phase on the chromatographic retention and thermodynamic characteristics of the adsorption of enantiomers of α-phenylcarboxylic acids on a chiral adsorbent with grafted antibiotic eremomycin. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2017. [DOI: 10.1134/s0036024417010228] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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11
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Reshetova E. Chromatographic retention and thermodynamics of the adsorption of α-phenylcarboxylic acid enantiomers on a chiral stationary phase with a grafted antibiotic eremomycin: Effect of eluent pH. J LIQ CHROMATOGR R T 2016. [DOI: 10.1080/10826076.2015.1137004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Elena Reshetova
- Institute of Technical Chemistry, The Ural Branch of the Russian Academy of Sciences, Perm, Russia
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12
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Graouer-Bacart M, Sayen S, Guillon E. Adsorption and co-adsorption of diclofenac and Cu(II) on calcareous soils. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2016; 124:386-392. [PMID: 26599281 DOI: 10.1016/j.ecoenv.2015.11.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 11/03/2015] [Accepted: 11/05/2015] [Indexed: 06/05/2023]
Abstract
Pharmaceuticals are emerging contaminants and their presence in different compartments of the environment has been detected in many countries. In this study, laboratory batch experiments were conducted to characterize the adsorption of diclofenac, a widely used non-steroidal anti-inflammatory drug, on six calcareous soils. The adsorption of diclofenac was relatively low, which may lead to a risk of groundwater contamination and plant uptake. A correlation between the soil-water distribution coefficient Kd and soil characteristics has been highlighted. Indeed, diclofenac adsorption as a function of soil organic matter content (% OM) and Rt=% CaCO3/% OM was successfully described through a simple empirical model, indicating the importance of considering the inhibiting effect of CaCO3 on OM retention properties for a better assessment of diclofenac fate in the specific case of calcareous soils. The simultaneous co-adsorption of diclofenac and copper - a ubiquitous pollutant in the environment - at the water/soil interface, was also investigated. It appeared quite unexpectedly that copper did not have a significant influence on diclofenac retention.
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Affiliation(s)
- Mareen Graouer-Bacart
- Institut de Chimie Moléculaire de Reims (ICMR), UMR CNRS 7312, Groupe Chimie de Coordination, Université de Reims Champagne-Ardenne, BP 1039, 51687 Reims Cedex 2, France
| | - Stéphanie Sayen
- Institut de Chimie Moléculaire de Reims (ICMR), UMR CNRS 7312, Groupe Chimie de Coordination, Université de Reims Champagne-Ardenne, BP 1039, 51687 Reims Cedex 2, France.
| | - Emmanuel Guillon
- Institut de Chimie Moléculaire de Reims (ICMR), UMR CNRS 7312, Groupe Chimie de Coordination, Université de Reims Champagne-Ardenne, BP 1039, 51687 Reims Cedex 2, France
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13
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Schönherr D, Wollatz U, Haznar-Garbacz D, Hanke U, Box KJ, Taylor R, Ruiz R, Beato S, Becker D, Weitschies W. Characterisation of selected active agents regarding pKa values, solubility concentrations and pH profiles by SiriusT3. Eur J Pharm Biopharm 2015; 92:155-70. [PMID: 25758123 DOI: 10.1016/j.ejpb.2015.02.028] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 02/18/2015] [Accepted: 02/27/2015] [Indexed: 10/23/2022]
Abstract
The aim of this work was to determine pKa values and solubility properties of 34active agents using the SiriusT3 apparatus. The selected drug substances belong to the groups of ACE-inhibitors, β-blockers, antidiabetics and lipid lowering substances. Experimentally obtained pKa and intrinsic solubility values were compared to calculated values (program ACD/ChemSketch) and pKa values to published data as well. Solubility-pH profiles were generated to visualise the substance solubility over the gastrointestinal pH range. The relationship between the solubility characteristic of a substance, its bioavailability and categorisation according to the Biopharmaceutics Classification System (BCS) was examined as well. The results showed a good agreement between experimentally obtained, calculated and published pKa values. The measured and calculated intrinsic solubility values indicated several major deviations. All solubility-pH profiles showed the expected shape and appearance for acids, bases or zwitterionic substances. The obtained results for the pKa and solubility measurements of the examined active agents may help to predict their physicochemical behaviour in vivo, and to understand the bioavailability of the substances according to their BCS categorisation. The easy and reproducible determination of pKa and solubility values makes the SiriusT3 apparatus a useful tool in early stages of drug and formulation development.
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Affiliation(s)
- D Schönherr
- University of Greifswald, Center of Drug Absorption and Transport, Institute of Pharmacy, 17487 Greifswald, Germany
| | - U Wollatz
- University of Greifswald, Center of Drug Absorption and Transport, Institute of Pharmacy, 17487 Greifswald, Germany
| | - D Haznar-Garbacz
- University of Greifswald, Center of Drug Absorption and Transport, Institute of Pharmacy, 17487 Greifswald, Germany
| | - U Hanke
- University of Greifswald, Center of Drug Absorption and Transport, Institute of Pharmacy, 17487 Greifswald, Germany
| | - K J Box
- Sirius Analytical Ltd., Forest Row, East Sussex RH18 5DW, UK
| | - R Taylor
- Sirius Analytical Ltd., Forest Row, East Sussex RH18 5DW, UK
| | - R Ruiz
- Sirius Analytical Ltd., Forest Row, East Sussex RH18 5DW, UK
| | - S Beato
- Novartis Pharma AG, Technical Research & Development, 4056 Basel, Switzerland
| | - D Becker
- Vivo Drug Delivery GmbH, 8832 Wollerau, Switzerland
| | - W Weitschies
- University of Greifswald, Center of Drug Absorption and Transport, Institute of Pharmacy, 17487 Greifswald, Germany.
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14
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UV Spectroscopic Method for Determining pK a Values of Some Antipsychotic Drugs in Water and Acetonitrile–Water Binary Mixtures. J SOLUTION CHEM 2013. [DOI: 10.1007/s10953-013-0006-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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15
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Alexander S, de Vos WM, Castle TC, Cosgrove T, Prescott SW. Growth and shrinkage of pluronic micelles by uptake and release of flurbiprofen: variation of pH. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:6539-6545. [PMID: 22471962 DOI: 10.1021/la204262w] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The micellization of Pluronic triblock copolymers (P103, P123, and L43) in the presence of flurbiprofen at different pH was studied by small-angle neutron scattering (SANS), pulsed-field gradient stimulated-echo nuclear magnetic resonance (PFGSE-NMR), and surface tension measurements. Addition of flurbiprofen to the Pluronic at low pH leads to an increase in the fraction of micellization, aggregation number, and the core radius of the micelles. However, changing the pH to above the pKa of flurbiprofen in an ethanol/water mixture (∼6.5) reduces the fraction of micellization and results in a weaker interaction between the drug and micelles due to the increased drug solubility in aqueous solution.
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Affiliation(s)
- Shirin Alexander
- School of Chemistry, University of Bristol , Bristol BS8 1TS, U.K
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16
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The adsorption of Naproxen enantiomers on the chiral stationary phase Whelk-O1 under reversed-phase conditions: The effect of buffer composition. J Chromatogr A 2010; 1217:7055-64. [DOI: 10.1016/j.chroma.2010.08.073] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 07/29/2010] [Accepted: 08/26/2010] [Indexed: 11/24/2022]
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17
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Asnin LD, Guiochon G. Retention of Naproxen enantiomers on the chiral stationary phase Whelk-O1 under reversed-phase conditions. A reconsideration of the adsorption mechanism in the light of new experimental data. J Chromatogr A 2010; 1217:1709-11. [DOI: 10.1016/j.chroma.2010.01.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 12/26/2009] [Accepted: 01/06/2010] [Indexed: 11/26/2022]
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18
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On the enantioselectivity of the mass transfer kinetics and the adsorption equilibrium of Naproxen on the chiral stationary phase ()-Whelk-O1 under reversed-phase conditions. J Chromatogr A 2010; 1217:1320-31. [DOI: 10.1016/j.chroma.2009.12.066] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 12/16/2009] [Accepted: 12/21/2009] [Indexed: 11/18/2022]
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19
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Asnin L, Gritti F, Kaczmarski K, Guiochon G. Features of the adsorption of Naproxen on the chiral stationary phase (S,S)-Whelk-O1 under reversed-phase conditions. J Chromatogr A 2010; 1217:264-75. [DOI: 10.1016/j.chroma.2009.11.039] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 11/09/2009] [Accepted: 11/13/2009] [Indexed: 11/30/2022]
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20
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Reshetova EN, Asnin LD. The chromatographic behavior and thermodynamic characteristics of adsorption of profen enantiomers on silica gel with grafted eremomycin antibiotic. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2009. [DOI: 10.1134/s0036024409040062] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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21
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Features of the adsorption of naproxen enantiomers on weak chiral anion-exchangers in nonlinear chromatography. J Chromatogr A 2008; 1192:62-73. [DOI: 10.1016/j.chroma.2008.03.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2007] [Revised: 02/25/2008] [Accepted: 03/10/2008] [Indexed: 11/17/2022]
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22
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Babić S, Horvat AJ, Mutavdžić Pavlović D, Kaštelan-Macan M. Determination of pKa values of active pharmaceutical ingredients. Trends Analyt Chem 2007. [DOI: 10.1016/j.trac.2007.09.004] [Citation(s) in RCA: 348] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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23
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Meloun M, Bordovská S, Galla L. The thermodynamic dissociation constants of four non-steroidal anti-inflammatory drugs by the least-squares nonlinear regression of multiwavelength spectrophotometric pH-titration data. J Pharm Biomed Anal 2007; 45:552-64. [PMID: 17825517 DOI: 10.1016/j.jpba.2007.07.029] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Revised: 07/23/2007] [Accepted: 07/29/2007] [Indexed: 02/05/2023]
Abstract
The mixed dissociation constants of four non-steroidal anti-inflammatory drugs (NSAIDs) ibuprofen, diclofenac sodium, flurbiprofen and ketoprofen at various ionic strengths I of range 0.003-0.155, and at temperatures of 25 degrees C and 37 degrees C, were determined with the use of two different multiwavelength and multivariate treatments of spectral data, SPECFIT/32 and SQUAD(84) nonlinear regression analyses and INDICES factor analysis. The factor analysis in the INDICES program predicts the correct number of components, and even the presence of minor ones, when the data quality is high and the instrumental error is known. The thermodynamic dissociation constant pK(a)(T) was estimated by nonlinear regression of (pK(a), I) data at 25 degrees C and 37 degrees C. Goodness-of-fit tests for various regression diagnostics enabled the reliability of the parameter estimates found to be proven. PALLAS, MARVIN, SPARC, ACD/pK(a) and Pharma Algorithms predict pK(a) being based on the structural formulae of drug compounds in agreement with the experimental value. The best agreement seems to be between the ACD/pK(a) program and experimentally found values and with SPARC. PALLAS and MARVIN predicted pK(a,pred) values with larger bias errors in comparison with the experimental value for all four drugs.
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Affiliation(s)
- Milan Meloun
- Department of Analytical Chemistry, University of Pardubice, CZ 532 10 Pardubice, Czech Republic.
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Argemí A, Saurina J. Characterization of acid–base properties of unstable drugs using a continuous-flow system with UV–vis spectrophotometric detection. J Pharm Biomed Anal 2007; 44:859-66. [PMID: 17482788 DOI: 10.1016/j.jpba.2007.03.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Revised: 03/12/2007] [Accepted: 03/26/2007] [Indexed: 11/21/2022]
Abstract
In this paper, we propose a continuous-flow system for the study of the acid-base characteristics of unstable drugs. 5-Azacytidine has been selected as a first model of unstable compound, which progressively decomposes in aqueous solutions. Besides, other compounds undergoing hydrolysis and oxidation side reactions have been also analyzed to explore the performance of the method. In comparison with conventional batch titrations, the drug decomposition can be minimized by the continuous renewal of the analyte solution. The composition of the buffer mixture is varied on-line during the process from successive changes in the flow rates of acid and basic stock solutions. As a result, the pH value of the test solution is varied in a controlled manner in the range of 1-13. Multivariate curve resolution based on alternating least squares has been used to extract relevant information concerning the acid-base properties of analytes. Results from the continuous-flow system have been compared with those obtained, using batch spectrophotometric titrations, and in the case of fast degradations, the performance of the proposed procedure has been superior.
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Affiliation(s)
- Anna Argemí
- Department of Analytical Chemistry, University of Barcelona, Diagonal 647, Barcelona 08028, Spain
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Subirats X, Bosch E, Rosés M. Retention of ionisable compounds on high-performance liquid chromatography. J Chromatogr A 2006; 1121:170-7. [PMID: 16753172 DOI: 10.1016/j.chroma.2006.03.126] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2005] [Revised: 03/30/2006] [Accepted: 03/31/2006] [Indexed: 11/29/2022]
Abstract
In agreement with our previous studies and those of other authors, it is shown that much better fits of retention time as a function of pH are obtained for acid-base analytes when pH is measured in the mobile phase, than when pH is measured in the aqueous buffer when buffers of different nature are used. However, in some instances it may be more practical to measure the pH in the aqueous buffer before addition of the organic modifier. Thus, an open methodology is presented that allows prediction of chromatographic retention of acid-base analytes from the pH measured in the aqueous buffer. The model presented estimates the pH of the buffer and the pKa of the analyte in a particular acetonitrile/water mobile phase from the pH and pKa values in water. The retention of the analyte can be easily estimated, at a buffer pH close to the solute pKa, from these values and from the retentions of the pure acidic and basic forms of the analyte. Since in many instances, the analyte pKa values in water are not known, the methodology has been also tested by using Internet software, at reach of many chemists, which calculates analyte pKa values from chemical structure. The approach is successfully tested for some pharmaceutical drugs.
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Affiliation(s)
- Xavier Subirats
- Department of Analytical Chemistry, University of Barcelona, Martí i Franquès 1-11, E-08028 Barcelona, Spain
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26
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Miklautz H, Keller D, Lopez Holguin F, Woloszczak R. Automated determination of the pK a values of 4-hydroxybenzoic acid in cosolvent–water mixtures and related solvent effects using a modified HPLC system. Anal Bioanal Chem 2006; 384:1191-5. [PMID: 16482396 DOI: 10.1007/s00216-005-0278-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Revised: 09/13/2005] [Accepted: 12/08/2005] [Indexed: 10/25/2022]
Abstract
An automated spectrophotometric method based on an HPLC system with a diode array detector was used to determine the pK(a) values of compounds with low water solubility in a universal buffer containing acetonitrile as cosolvent. The column of the system was replaced with a capillary connecting the injection system and the diode array detector. Specific solvent effects were corrected for using the dielectric constants of the mixed solvent and pure water. The method was tested using 4-hydroxybenzoic acid and the results were compared with those obtained with a spectrophotometer. Linear regression lines with different slopes were obtained from spectrophotometric measurements of different cosolvent-water mixtures. These effects were shown to depend upon the polarity of the solvent-water mixture, and they were explained by the solvatochromic behavior of the 4-hydroxybenzoic acid in the solvent-water mixture.
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Affiliation(s)
- H Miklautz
- Schering AG - AD Physical Chemistry, Müllerstr. 178 ADP - S149, 13342 Berlin, Germany.
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27
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Critical validation of a new simpler approach to estimate aqueous pKa of drugs sparingly soluble in water. Anal Chim Acta 2005. [DOI: 10.1016/j.aca.2005.06.058] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Tyman-Szram B, Musiol R, Sajewicz M, Polanski J. Thin-layer chromatographic determination of the pKavalues of organic acids and bases. JPC-J PLANAR CHROMAT 2005. [DOI: 10.1556/jpc.18.2005.4.14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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29
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Kaliszan R, Wiczling P, Markuszewski MJ. pH gradient high-performance liquid chromatography: theory and applications. J Chromatogr A 2004; 1060:165-75. [PMID: 15628159 DOI: 10.1016/j.chroma.2004.04.081] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
pH gradient high-performance liquid chromatography (HPLC) is a method of reversed-phase high-performance liquid chromatography suitable for ionogenic substances. It consists in programmed increase during the chromatographic process of the eluting strength of eluent with respect to the analytes separated. On the analogy of the conventional organic modifier gradient reversed-phase HPLC, in the pH gradient approach the eluting strength of the mobile phase increases due to its changing pH: increasing in case of acids or decreasing in case of bases. At the same time the content of organic modifier remains constant. A theory of the pH gradient HPLC has been elaborated. The resulting mathematical model is easily manageable. Its ability to predict changes in retention and separation of analytes following the changes in chromatographic conditions is demonstrated. The pH gradient method is uniquely suitable to determine pKa values of analytes. An equation is presented allowing to calculate pKa values basing on appropriate retention data. The effects on pKa are discussed of the concentration of methanol in the mobile phase. The RP HPLC-derived pKa data correlate to the reference pKa values (w(w)pKa) but are not identical. That may be explained by the effects on the chromatographically determined pKa of the specific interactions of analytes with stationary phases. The proposed pH gradient RP HPLC procedure offers a fast and convenient means to get comparable acidity parameters for larger series of compounds, like drug candidates, also when the analytes are available only in minute amounts and/or as complex mixtures.
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Affiliation(s)
- Roman Kaliszan
- Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdańsk, Gen. J. Hallera 107, Gdańsk 80-416, Poland.
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30
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Wiczling P, Markuszewski MJ, Kaliszan R. Determination of pKa by pH Gradient Reversed-Phase HPLC. Anal Chem 2004; 76:3069-77. [PMID: 15167784 DOI: 10.1021/ac049807q] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
pH gradient reversed-phase HPLC consists of a programmed increase during the chromatographic run of the eluting power of the mobile phase with regard to ionizable analytes. On the analogy of the conventional organic modifier gradient RP HPLC, in the pH gradient mode, the eluting strength of the mobile phase increases due to its increasing (with acid analytes) or decreasing (with basic analytes) pH, whereas the content of organic modifier is kept constant. We have shown previously that the pH gradient separations are technically possible using standard chromatographic equipment. Here we demonstrate that the method is uniquely suitable to determine pK(a) values of analytes. A strict theoretical model is proposed to determine pK(a) values based on the retention data from a pH gradient RP HPLC run. The pK(a) data so obtained are discussed in relation to the concentration of methanol in the mobile phase, the type of stationary phase, and the duration of the gradient. The pK(a) values determined by the pH gradient method are related to the respective data obtained conventionally in a series of isocratic experiments. A close similarity of the two types of chromatographically determined pK(a) data is demonstrated. The HPLC-derived pK(a) parameters correlate to the literature pK(a) values determined by titrations in water. The chromatographically derived and the reference pK(a) values are not identical, however. That is probably due to the effects on the chromatographic pK(a) of the specific sites of interactions with analytes on the surfaces of the HPLC stationary phases. Nonetheless, the proposed pH gradient HPLC method may supply in a fast and convenient manner comparable acidity parameters for larger series of drug candidates, including those available in only minute amounts, without need of their purification, and also when the compounds are provided as complex mixtures, like those produced by combinatorial chemistry.
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Affiliation(s)
- Paweł Wiczling
- Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdańsk, Gen. J. Hallera 107, 80-416 Gdansk, Poland
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31
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Rosés M. Determination of the pH of binary mobile phases for reversed-phase liquid chromatography. J Chromatogr A 2004; 1037:283-98. [PMID: 15214671 DOI: 10.1016/j.chroma.2003.12.063] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The measurement of pH in chromatographic mobile phases has been a constant subject of discussion during many years. The pH of the mobile phase is an important parameter that determines the chromatographic retention of many analytes with acid-base properties. In many instances a proper pH measurement is needed to assure the accuracy of retention-pH relationships or the reproducibility of chromatographic procedures. Three different methods are common in pH measurement of mobile phases: measurement of pH in the aqueous buffer before addition of the organic modifier, measurement of pH in the mobile phase prepared by mixing aqueous buffer and organic modifier after pH calibration with standard solutions prepared in the same mobile phase solvent, and measurement of pH in the mobile phase prepared by mixing aqueous buffer and organic modifier after pH calibration with aqueous standard solutions. This review discusses the different pH measurement and calibration procedures in terms of the theoretical and operational definitions of the different pH scales that can be applied to water-organic solvent mixtures. The advantages and disadvantages of each procedure are also presented through chromatographic examples. Finally, practical recommendations to select the most appropriate pH measurement procedure for particular chromatographic problems are given.
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Affiliation(s)
- Martí Rosés
- Department de Química Analítica, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona, Spain.
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Ruiz R, Ràfols C, Rosés M, Bosch E. A potentially simpler approach to measure aqueous pKa of insoluble basic drugs containing amino groups. J Pharm Sci 2003; 92:1473-81. [PMID: 12820151 DOI: 10.1002/jps.10415] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The aqueous pK values ((w/w)pK(a)) of several sparingly water-soluble drugs with amino groups have been calculated from pK values determined in several methanol/water mixtures ((s/s)pK(a)) by means of the Yasuda-Shedlovsky equation and by a linear equation that relates ((w/w)pK(a)) of amino compounds with ((s/s)pK(a)) obtained in any particular methanol/water mixture. Parameters of this last equation for amino compounds can be easily calculated from solely the methanol content of the solvent. Results from both approaches are consistent. However, Yasuda-Shedlovsky equation requires several ((s/s)pK(a)) determinations in solutions with different methanol content and can be used only from measurements in solutions with a maximum methanol content of about 65% in weight. In contrast, the linear proposed equation allows a very good estimation of ((w/w)pK(a)) from only one experimental ((s/s)pK(a)) value, and it permits this estimation from ((s/s)pK(a)) determined in a solution very rich in methanol. Therefore, it is suitable for very insoluble compounds. The examined amino compounds cover a wide range ((w/w)pK(a)) from 6.7 to 10.6, which have been estimated from experimental ((s/s)pK(a)) values in the whole composition range. In all instances consistent and satisfactory results have been achieved.
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Affiliation(s)
- Rebeca Ruiz
- Departament de Química Analítica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain
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33
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Rosés M, Bosch E. Influence of mobile phase acid-base equilibria on the chromatographic behaviour of protolytic compounds. J Chromatogr A 2002; 982:1-30. [PMID: 12489853 DOI: 10.1016/s0021-9673(02)01444-9] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A review about the influence of mobile phase acid-base equilibria on the liquid chromatography retention of protolytic analytes with acid-base properties is presented. The general equations that relate retention to mobile phase pH are derived and the different procedures to measure the pH of the mobile phase are explained. These procedures lead to different pH scales and the relationships between these scales are presented. IUPAC rules for nomenclature of the different pH are also presented. Proposed literature buffers for pH standardization in chromatographic mobile phases are reviewed too. Since relationships between analyte retention and mobile phase pH depends also on the pKa value of the analyte, the solute pKa data in water-organic solvent mixtures more commonly used as chromatographic mobile phase are also reviewed. The solvent properties that produce variation of the pKa values with solvent composition are discussed. Chromatographic examples of the results obtained with the different procedures for pH measurement are presented too. Application to the determination of aqueous pKa values from chromatographic retention data is also critically discussed.
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Affiliation(s)
- Martí Rosés
- Departament de Química Analítica, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona, Spain.
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Espinosa S, Bosch E, Rosés M. Retention of ionizable compounds in high-performance liquid chromatography. 14. Acid-base pK values in acetonitrile-water mobile phases. J Chromatogr A 2002; 964:55-66. [PMID: 12198856 DOI: 10.1016/s0021-9673(02)00558-7] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Linear relationships between sspKa values in acetonitrile-water mixtures and wwpKa values in pure water have been established for five families of compounds: aliphatic carboxylic acids, aromatic carboxylic acids, phenols, amines, and pyridines. The parameters (slope and intercept) of the linear correlations have been related with acetonitrile-water composition. The proposed equations allow accurate estimation of the pKa values of any member of the studied families at any acetonitrile-water composition up to 60% of acetonitrile in volume (100% for pyridines). Conversely, the same equations can be used to estimate aqueous pKa values from chromatographic pKa values obtained from any acetonitrile-water mobile phase between the composition range studied. Estimation of pKa values have been tested with chromatographic literature data.
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Affiliation(s)
- Sonia Espinosa
- Departament de Química Analítica, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona, Spain
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