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Allegri G, Huskens J, Martinho RP, Lindhoud S. Distribution of polyelectrolytes and counterions upon polyelectrolyte complexation. J Colloid Interface Sci 2024; 672:654-663. [PMID: 38865879 DOI: 10.1016/j.jcis.2024.06.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Revised: 06/06/2024] [Accepted: 06/06/2024] [Indexed: 06/14/2024]
Abstract
HYPOTHESIS Understanding polyelectrolyte complexation remains limited due to the absence of a systematic methodology for analyzing the distribution of components between the polyelectrolyte complex (PEC) and the dilute phases. EXPERIMENTS We developed a methodology based on NMR to quantify all components of solid-like PECs and their supernatant phases formed by mixing different ratios of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid)-sodium salt (PAA). This approach allowed for determining relative and absolute concentrations of polyelectrolytes in both phases by 1H NMR studies. Using 23Na and 35Cl NMR spectroscopy we measured the concentration of counterions in both phases. FINDINGS Regardless of the mixing ratio of the polyelectrolytes the PEC is charge-stoichiometric, and any excess polyelectrolytes to achieve charge stoichiometry remains in the supernatant phase. The majority of counterions were found in the supernatant phase, confirming counterion release being a major thermodynamic driving force for PEC formation. The counterion concentrations in the PEC phase were approximately twice as high as in the supernatant phase. The complete mass balance of PEC formation could be determined and translated into a molecular picture. It appears that PAH is fully charged, while PAA is more protonated, so less charged, and some 10% extrinsic PAH-Cl- pairs are present in the complex.
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Affiliation(s)
- Giulia Allegri
- Molecular Nanofabrication Group, Department for Molecules & Materials, MESA+ Institute & Faculty of Science Technology, University of Twente, 7500 AE Enschede, the Netherlands.
| | - Jurriaan Huskens
- Molecular Nanofabrication Group, Department for Molecules & Materials, MESA+ Institute & Faculty of Science Technology, University of Twente, 7500 AE Enschede, the Netherlands.
| | - Ricardo P Martinho
- Biomolecular Nanotechnology Group, Department for Molecules & Materials, MESA+ Institute & Faculty of Science Technology, University of Twente, 7500 AE Enschede, the Netherlands.
| | - Saskia Lindhoud
- Molecular Nanofabrication Group, Department for Molecules & Materials, MESA+ Institute & Faculty of Science Technology, University of Twente, 7500 AE Enschede, the Netherlands.
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Lin Q, Meng C, Liu J, Liu F, Zhou Q, Liu J, Peng C, Xiong L. An Optimized Two-Dimensional Quantitative Nuclear Magnetic Resonance Strategy for the Rapid Quantitation of Diester-Type C 19-Diterpenoid Alkaloids from Aconitum carmichaelii. Anal Chem 2023. [PMID: 37209123 DOI: 10.1021/acs.analchem.2c05109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
With the development of nuclear magnetic resonance (NMR) spectrometers and probes, two-dimensional quantitative nuclear magnetic resonance (2D qNMR) technology with a high signal resolution and great application potential has become increasingly accessible for the quantitation of complex mixtures. However, the requirement that the relaxation recovery time be equal to at least five times T1 (longitudinal relaxation time) makes it difficult for 2D qNMR to simultaneously achieve high quantitative accuracy and high data acquisition efficiency. By comprehensively using relaxation optimization and nonuniform sampling, we successfully established an optimized 2D qNMR strategy for HSQC experiments at the half-hour level and then accurately quantified the diester-type C19-diterpenoid alkaloids in Aconitum carmichaelii. The optimized strategy had the advantages of high efficiency, high accuracy, good reproducibility, and low cost and thus could serve as a reference to optimize 2D qNMR experiments for quantitative analysis of natural products, metabolites, and other complex mixtures.
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Affiliation(s)
- Qiao Lin
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Chunwang Meng
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Jie Liu
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Fei Liu
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Qinmei Zhou
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Innovative Institute of Chinese Medicine and Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Juan Liu
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Cheng Peng
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Liang Xiong
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Institute of Innovative Medicine Ingredients of Southwest Specialty Medicinal Materials, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
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Rubim de Santana PI, Diz de Almeida JSF, França TCC, Junker J. Quantitative NMR Interpretation without Reference. JOURNAL OF ANALYTICAL METHODS IN CHEMISTRY 2022; 2022:7490691. [PMID: 36406159 PMCID: PMC9671720 DOI: 10.1155/2022/7490691] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 10/12/2022] [Accepted: 10/18/2022] [Indexed: 06/16/2023]
Abstract
As has been documented numerous times over the years, nuclear magnetic resonance (NMR) experiments are intrinsically quantitative. Still, quantitative NMR methods have not been widely adopted or largely introduced into pharmacopoeias. Here, we describe the quantitative interpretation of the 1D proton NMR experiment using only absolute signal intensities with the variation of common experimental parameters and their application.
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Affiliation(s)
- Priscila Ivo Rubim de Santana
- Laboratory of Molecular Modeling Applied to Chemical em Biological Defense (LMCBD), Military Institute of Engineering, Rio de Janeiro 22290-270, Brazil
- Oswaldo Cruz Foundation, CDTS, Av. Brasil 4365, Rio de Janeiro 21040-900, Brazil
| | | | - Tanos Celmar Costa França
- Laboratory of Molecular Modeling Applied to Chemical em Biological Defense (LMCBD), Military Institute of Engineering, Rio de Janeiro 22290-270, Brazil
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, Rokitanskeho 62, 500 03 Hradec Kralove, Czech Republic
| | - Jochen Junker
- Oswaldo Cruz Foundation, CDTS, Av. Brasil 4365, Rio de Janeiro 21040-900, Brazil
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Achanta PS, Niemitz M, Friesen JB, Tadjimukhamedov FK, Bzhelyansky A, Giancaspro GI, Chen SN, Pauli GF. Pharmaceutical analysis by NMR can accommodate strict impurity thresholds: The case of choline. J Pharm Biomed Anal 2022; 214:114709. [PMID: 35339885 DOI: 10.1016/j.jpba.2022.114709] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/23/2022] [Accepted: 03/03/2022] [Indexed: 11/19/2022]
Abstract
The ICH guidelines recommend reporting thresholds for regular impurities in drug substances at the level of 0.05% or 0.03% (w/w) depending on the maximum daily intake. Therefore, any instrumental method of analysis applicable to the impurity analysis should be able to detect and quantify the analytes at those levels. This investigation was designed to verify the suitability of 1H NMR spectroscopy for the detection of impurities, as a first step in the process before attempting quantification. In order to minimize demand on equipment, this study employed a 400 MHz instrument for structural confirmation and signal assignments of choline (1) and O-(2-hydroxyethyl)choline (2), a known impurity. The limit of detection (LOD) of 2 in 10 mg of 1 was established as 0.01% on a 400 MHz instrument and 2% on a 60 MHz (benchtop) NMR spectrometer. Thus, impurities for which quantification is required are readily detected at 400 MHz or above. These results are in contrast to the widespread belief that 1H NMR sensitivity is insufficient for pharmaceutical impurity analysis. The choice of solvent was recognized as a critical parameter for 1H NMR LOD analysis. Furthermore, publicly available NMR raw data (HMDB) proved to be valuable for unveiling the otherwise cryptic information hidden in complex signal patterns via 1H NMR iterative Full Spin Analysis. Finally, the study uncovered the less noticed, yet characteristic, 14N-1H coupling in the -N+(CH3)3 groups, adding strong arguments for the Raw NMR Data Initiative. Collectively, the data prove that the analytical capabilities of high-field NMR easily fulfill the ICH requirements for detection of impurity in the presence of an actual substance of interest which makes it a step closer to achieving regulatory standards.
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Affiliation(s)
- Prabhakar S Achanta
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612, USA; Pharmacognosy Institute, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612, USA
| | - Matthias Niemitz
- NMR Solutions Limited, Tulliportinkatu 3 A 8, 70100 Kuopio, Finland
| | - J Brent Friesen
- Pharmacognosy Institute, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612, USA; Center for Natural Product Technologies (CENAPT), College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612, USA; Physical Sciences Department, Rosary College of Arts and Sciences, Dominican University, 7900 West Division Street, River Forest, IL 60305, USA
| | | | - Anton Bzhelyansky
- The United States Pharmacopeial Convention, 12601 Twinbrook Pkwy, Rockville, MD 20852, USA
| | - Gabriel I Giancaspro
- The United States Pharmacopeial Convention, 12601 Twinbrook Pkwy, Rockville, MD 20852, USA
| | - Shao-Nong Chen
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612, USA; Pharmacognosy Institute, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612, USA; Center for Natural Product Technologies (CENAPT), College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612, USA
| | - Guido F Pauli
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612, USA; Pharmacognosy Institute, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612, USA; Center for Natural Product Technologies (CENAPT), College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612, USA.
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Ruiz-Muelle AB, Lestón-Cabeo F, Fernández I. Accurate detection of perchlorate in epoxy resins via chlorine-35 quantitative quadrupolar NMR (qQNMR). Analyst 2022; 147:5075-5081. [DOI: 10.1039/d2an00759b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We present herein the application of a qQNMR method that uses a quadrupolar nucleus such as chlorine-35 for the quantification of perchlorate in epoxy resins.
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Affiliation(s)
- Ana Belén Ruiz-Muelle
- Department of Chemistry and Physics, Research Centre CIAIMBITAL, University of Almería, Ctra. Sacramento, s/n, 04120, Almería, Spain
| | - Felipe Lestón-Cabeo
- Department of Chemistry and Physics, Research Centre CIAIMBITAL, University of Almería, Ctra. Sacramento, s/n, 04120, Almería, Spain
| | - Ignacio Fernández
- Department of Chemistry and Physics, Research Centre CIAIMBITAL, University of Almería, Ctra. Sacramento, s/n, 04120, Almería, Spain
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Ruiz-Muelle AB, Díaz Navarro C, Fernández I. Quantitative Quadrupolar NMR (qQNMR) via nitrogen-14 for the accurate control of L-carnitine in food supplements. J Pharm Biomed Anal 2021; 210:114548. [PMID: 34959006 DOI: 10.1016/j.jpba.2021.114548] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 12/16/2021] [Accepted: 12/20/2021] [Indexed: 01/26/2023]
Abstract
A qQNMR methodology using nitrogen-14 as the quadrupolar nucleus of choice has been introduced for the first time as a robust and validated method to determine and quantify L-carnitine in food supplements. The quantification has been carried out by the alternative use of a calibration curve or by addition of ammonium chloride as internal standard. The method was validated at seven concentration levels in the range of 5.58-99.26 mM, affording intra- and inter day accuracies lower than 6.84% (expressed in CV), robustness towards temperature and recycle delay, limit of detection (LOD) of 2.48 mM, limit of quantification (LOQ) of 5.58 mM and remarkably with absence of matrix effect.
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Affiliation(s)
- Ana Belén Ruiz-Muelle
- Department of Chemistry and Physics, Research Centre CIAIMBITAL, University of Almería, Ctra. Sacramento, s/n, 04120 Almería, Spain
| | - Concepción Díaz Navarro
- Department of Chemistry and Physics, Research Centre CIAIMBITAL, University of Almería, Ctra. Sacramento, s/n, 04120 Almería, Spain
| | - Ignacio Fernández
- Department of Chemistry and Physics, Research Centre CIAIMBITAL, University of Almería, Ctra. Sacramento, s/n, 04120 Almería, Spain.
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