A Rapid and Feasible 1H-NMR Quantification Method of Ephedrine Alkaloids in Ephedra Herbal Preparations

A highly specific and sensitive proton nuclear magnetic resonance (1H-NMR) method has been developed for the quantification of ephedrine alkaloid derivatives in Ephedra herbal commercial prescriptions. At the region of δ 4.0 to 5.0 ppm in the 1H NMR spectrum, the characteristic signals are separated well from each other, and six analogues in total, methylephedrine (ME), ephedrine (EP), norephedrine (NE), norpseudoephedrine (NP), pseudoephedrine (PE), and methylpseudoephedrine (MP) could be identified. The quantities of these compounds are calculated by the relative ratio of the integral values of the target peak for each compound to the known concentrations of the internal standard anthracene. The present method allows for a rapid and simple quantification of ephedrine alkaloid derivatives in Ephedra-related commercial prescriptions without any preliminary purification steps and standard compounds, and accordingly it can be a powerful tool to verify different Ephedra species. In comparison to conventional chromatographic methods, the advantages of this method include the fact that no standard compounds are required, the quantification can be directly performed on the crude extracts, a better selectivity for various ephedrine alkaloid derivatives, and the fact that a very significant time-gain may be achieved.

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Simple HNMR Spectroscopic Method for Assay of Salts of the Contrast Agent Diatrizoate in Commercial Solutions

Journal of AOAC International ◽

10.1093/jaoac/79.4.833 ◽

1996 ◽

Vol 79 (4) ◽

pp. 833-838 ◽

Cited By ~ 5

Author(s):

George M Hanna ◽

Cesar A Lau-Cam

Keyword(s):

Standard Deviation ◽

Contrast Agent ◽

1H Nmr ◽

Sodium Acetate ◽

Spectroscopic Method ◽

Internal Standard ◽

Fixed Amount ◽

Nmr Spectrum ◽

Nmr Method ◽

Molecular Components

Abstract A simple, accurate, and specific 1H NMR spectroscopic method was developed for the assay of diatrizoate meglumine or the combination diatrizoate meglumine and diatrizoate sodium in commercial solutions for injection. A mixture of injectable solution and sodium acetate, the internal standard, was diluted with D20 and the 1H NMR spectrum of the solution was obtained. Two approaches were used to calculate the drug content, based on the integral values for the -N-CO-CH3 protons of diatrizoic acid at 2.23 ppm, the N-CH3 protons of meglumine at 2.73 ppm, and the CH3-CO-protons of sodium acetate at 1.9 ppm. Recoveries (mean ± standard deviation) of diatrizoic acid and meglumine from 10 synthetic mixtures of various amounts of these compounds with a fixed amount of internal standard were 100.3 ±; 0.55% and 100.1 ± 0.98%, respectively. In addition to providing a direct means of simultaneously assaying diatrizoic acid and meglumine, the proposed NMR method can also be used to identify diatrizoate meglumine and each of its molecular components.

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Stability-Indicating Proton Nuclear Magnetic Resonance Spectroscopic Method for Determination of S-Adenosyl-L-Methionine in Tablets

Journal of AOAC International ◽

10.1093/jaoac/78.2.353 ◽

1995 ◽

Vol 78 (2) ◽

pp. 353-357 ◽

Cited By ~ 3

Author(s):

Larry K Revelle ◽

D André d’Avignon ◽

John C Reepmeyer ◽

Richard C Zerfing

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Spectroscopic Method ◽

Internal Standard ◽

Proton Nuclear Magnetic Resonance ◽

Stability Indicating ◽

Nmr Method ◽

Relative Standard ◽

The Stability ◽

Nuclear Magnetic

Abstract We present a simple, accurate, stability-indicating nuclear magnetic resonance (NMR) method for determining active (S,S) and inactive (R,S) epimers of S-adenosyl-L-methionine (SAM) in tablets. The SCH3 resonances of SAM epimers were well resolved at 300 MHz. Individual assays of 5 SAM tablets gave SAM values of 101.3 ± 1.7% of declared amounts. Tablet solutions were assayed at a level of 8.0 mg/mL, but the method was linear for SAM concentrations ranging from 64 to 1 mg/mL (correlation coefficient, 0.9996). Reproducibility was indicated by a relative standard deviation of 0.33% for 6 replicate assays for total SAM at a concentration of 8 mg/mL. In contrast to the propietary liquid chromatographic (LC) method, which requires SAM as an external standard, the NMR method uses sodium trimethylsilylpropionate-d4 (TSP) both as an internal standard and as a chemical shift reference. The method was used to test the stability of SAM analytes under various pH levels and temperatures. We found 8% inactivation of SAM due to epimerization over a 24 h period at room temperature and pH 5. SAM solutions showed no detectable inactivation after 14 days when stored below 0°C.

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Polyhydroxyalkanoate quantification in organic wastes and pure cultures using a single-step extraction and 1H NMR analysis

Water Science & Technology ◽

10.2166/wst.2012.273 ◽

2012 ◽

Vol 66 (5) ◽

pp. 1000-1006 ◽

Cited By ~ 12

Author(s):

Elisabeth Linton ◽

Asif Rahman ◽

Sridhar Viamajala ◽

Ronald C. Sims ◽

Charles D. Miller

Keyword(s):

1H Nmr ◽

Azotobacter Vinelandii ◽

Nile Blue ◽

Agricultural Waste ◽

Accurate Method ◽

Single Step ◽

Proton Nuclear Magnetic Resonance ◽

Copolymer Composition ◽

Nmr Analysis ◽

Nmr Method

In this study, a proton nuclear magnetic resonance (1H NMR) method was developed to quantitatively analyze polyhydroxyalkanoate (PHA) content in Cupriavidus necator H16, Azotobacter vinelandii AvOP, and mixed microbial cultures from the effluent of an agricultural waste treatment anaerobic digester. In contrast to previous methods, a single-step PHA extractive method using deuterated chloroform was established, thereby facilitating direct 1H NMR analysis. The accuracy of the method was verified through comparison with well-established gas chromatography (GC) methanolysis techniques. Nile blue fluorescence staining was also carried out to serve as an independent and qualitative indicator of intracellular PHA content. The results indicate that the 1H NMR method is appropriate for rapid and non-destructive quantification of overall PHA content and determination of PHA copolymer composition in a variety of cultures. Notably, this technique was effective in measuring PHA content in full-strength waste samples where high concentrations of background impurities and organic compounds are present. The straightforward procedures minimize error-introducing steps, require less time and materials, and result in an accurate method suitable for routine analyses.

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One-Dimensional 13C NMR Is a Simple and Highly Quantitative Method for Enantiodiscrimination

Molecules ◽

10.3390/molecules23071785 ◽

2018 ◽

Vol 23 (7) ◽

pp. 1785 ◽

Cited By ~ 5

Author(s):

Peter Lankhorst ◽

Jozef van Rijn ◽

Alexander Duchateau

Keyword(s):

1H Nmr ◽

13C Nmr ◽

Quantitative Method ◽

Enantiomeric Excess ◽

Nmr Spectrum ◽

One Dimensional ◽

Nmr Method ◽

Relative Standard ◽

Excess Value ◽

Chiral Solvating Agent

The discrimination of enantiomers of mandelonitrile by means of 1D 13C NMR and with the aid of the chiral solvating agent (S)-(+)-1-(9-anthryl)-2,2,2-trifluoroethanol (TFAE) is presented. 1H NMR fails for this specific compound because proton signals either overlap with the signals of the chiral solvating agent or do not show separation between the (S)-enantiomer and the (R)-enantiomer. The 13C NMR method is validated by preparing artificial mixtures of the (R)-enantiomer and the racemate, and it is shown that with only 4 mg of mandelonitrile a detection limit of the minor enantiomer of 0.5% is obtained, corresponding to an enantiomeric excess value of 99%. Furthermore, the method shows high linearity, and has a small relative standard deviation of only 0.3% for the minor enantiomer when the relative abundance of this enantiomer is 20%. Therefore, the 13C NMR method is highly suitable for quantitative enantiodiscrimination. It is discussed that 13C NMR is preferred over 1H NMR in many situations, not only in molecules with more than one chiral center, resulting in complex mixtures of many stereoisomers, but also in the case of molecules with overlapping multiplets in the 1H NMR spectrum, and in the case of molecules with many quaternary carbon atoms, and therefore less abundant protons.

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Study of Configurational Sequence Structures of Poly(Butadiene)s by Carbon-13 Proton Decoupled Fourier Transform Nuclear Magnetic Resonance Spectroscopy

Rubber Chemistry and Technology ◽

10.5254/1.3542907 ◽

1973 ◽

Vol 46 (2) ◽

pp. 350-358 ◽

Cited By ~ 8

Author(s):

Yasuhide Alaki ◽

Toshio Yoshimoto ◽

Mamoru Imanari ◽

Makoto Takeuchi

Keyword(s):

Nuclear Magnetic Resonance ◽

Fourier Transform ◽

Magnetic Resonance ◽

Magnetic Resonance Spectroscopy ◽

Polymer Chains ◽

Proton Nuclear Magnetic Resonance ◽

Resonance Spectroscopy ◽

Sequence Structure ◽

Nmr Method ◽

Nuclear Magnetic

Abstract Carbon-13 proton nuclear magnetic resonance (NMR) of poly(butadiene) s consisting of various ratios of cis-1,4-, trans-1,4- and 1,2-structures were measured by the pulsed Fourier transform NMR method. The spectra of poly(butadiene)s with two or three kinds of butadiene configurations show several new signals which were not observed for homopolymers comprising merely one kind of butadiene configuration. All of these peaks are ascribed to the carbons linked by different kinds of configurations. From these results, the configurational sequence structure of butadiene units in polymer chains has been revealed.

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OBETICHOLIC ACID: AN INSIGHT INTO A QUANTITATIVE DETERMINATION AND METHODOLOGICAL VALIDATION THROUGH NUCLEAR MAGNETIC RESONANCE

International Journal of Applied Pharmaceutics ◽

10.22159/ijap.2020v12i6.38944 ◽

2020 ◽

pp. 179-190

Author(s):

RAKESH SAHU ◽

RAKHI MISHRA ◽

CHANDANA MAJEE ◽

AJAY KUMAR ◽

RUPA MAZUMDER

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Quantitative Determination ◽

Method Validation ◽

Limit Of Detection ◽

Internal Standard ◽

Proton Nuclear Magnetic Resonance ◽

Obeticholic Acid ◽

Relative Standard ◽

Nuclear Magnetic

Objective: The research work unveils the use of nuclear magnetic resonance (NMR) technique for quantitative determination and method validation of obeticholic acid. As standard expository methodology for more up to date medications or formulations may not be available in pharmacopeias, hence it is fundamental need to create novel analytical procedures which should be precise and accurate. Methods: Proton (1H) and carbon (13C) NMR analysis were initially performed to confirm the preliminary authenticity of obeticholic acid API. Method validation was accomplished on the basis of standard guidelines for the parameters, in which tetramethylbenzene as an internal standard and deuterated dimethyl sulfoxide as a diluent were used to assess the obeticholic acid. Results: For the quantification of the drug, the proton nuclear magnetic resonance signals at 0.602 ppm and 6.86 ppm corresponding to the analyte proton of drug and internal standard respectively were used. The curve equation calculated from the regression method, the relative-standard-deviation and correlation-coefficient were found to be 0.743% and 0.9989 respectively, indicating good linearity. Consequently, the quantitative assay of the drug was found to be 99.91% in linearity with limit of detection and quantification values as 0.0773 mg and 0.2344 mg respectively, making successful the study of method validation for obeticholic acid. Conclusion: The advantage of the method was that no reference standard of analyte drug was required for quantification and method validation. The method is non-destructive and can be applied for quantification of drug in commercial pharmaceutical formulation products.

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Proton Nuclear Magnetic Resonance (1H NMR) profiling of isolated organs in the snail Helix aspersa maxima

Ecological Indicators ◽

10.1016/j.ecolind.2019.05.058 ◽

2019 ◽

Vol 105 ◽

pp. 177-187 ◽

Cited By ~ 1

Author(s):

Devalckeneer Aude ◽

Bouviez Marion ◽

Conotte Raphaël ◽

Jean-Marie Colet

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

1H Nmr ◽

Helix Aspersa ◽

Proton Nuclear Magnetic Resonance ◽

Isolated Organs ◽

Snail Helix Aspersa ◽

Helix Aspersa Maxima ◽

Nuclear Magnetic

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Quantitative Analysis of Apoptotic Cell Death Using Proton Nuclear Magnetic Resonance Spectroscopy

Blood ◽

10.1182/blood.v89.10.3778 ◽

1997 ◽

Vol 89 (10) ◽

pp. 3778-3786 ◽

Cited By ~ 106

Author(s):

Francis G. Blankenberg ◽

Peter D. Katsikis ◽

Richard W. Storrs ◽

Christian Beaulieu ◽

Daniel Spielman ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

Cell Death ◽

Magnetic Resonance ◽

1H Nmr ◽

Signal Intensity ◽

Intensity Ratio ◽

Apoptotic Cell ◽

Proton Nuclear Magnetic Resonance ◽

Resonance Spectroscopy ◽

Signal Intensity Ratio

Abstract Quantification of apoptotic cell death in vivo has become an important area of investigation in patients with acute lymphoblastic leukemia (ALL). We have devised a noninvasive analytical method to estimate the percentage of apoptotic lymphoblasts in doxorubicin-treated Jurkat T-cell ALL cultures, using proton nuclear magnetic resonance spectroscopy (1H NMR). We have found that the ratio of the methylene (CH2 ) resonance (at 1.3 ppm) to the methyl (CH3 ) resonance (at 0.9 ppm) signal intensity, as observed by 1H NMR, is directly proportional to the percentage of apoptotic lymphoblasts in vitro. The correlation between the CH2/CH3 signal intensity ratio and the percentage of apoptotic lymphoblasts was optimal 24 to 28 hours after doxorubicin treatment (r2 = .947, N = 27 samples). There was also a direct temporal relationship between an increase in the CH2/CH3 signal intensity ratio and the onset of apoptosis as detected by nuclear morphologic analysis, fluorescein-annexin V flow cytometry, and DNA gel electrophoresis. Thin-layer chromatography confirmed that a dynamic and/or compositional change of the plasma membrane, rather than increases in lipase activity or fatty acid production, appears to account for the increase in the CH2/CH3 signal intensity ratio during apoptosis. 1H NMR may have clinical utility for the early noninvasive assessment of chemotherapeutic efficacy in patients with ALL.

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Determination of Ephedrine, Pseudoephedrine, and Norephedrine in Mixtures (Bulk and Dosage Forms) by Proton Nuclear Magnetic Resonance Spectroscopy

Journal of AOAC International ◽

10.1093/jaoac/78.4.946 ◽

1995 ◽

Vol 78 (4) ◽

pp. 946-953 ◽

Cited By ~ 11

Author(s):

George M Hanna

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Spectroscopic Method ◽

Internal Standard ◽

Dosage Forms ◽

Proton Nuclear Magnetic Resonance ◽

Resonance Spectroscopy ◽

1H Nuclear Magnetic Resonance ◽

Nuclear Magnetic

Abstract A simple, specific, and accurate 1H nuclear magnetic resonance (NMR) spectroscopic method has been developed for quantitative determination of the Ephedra alkaloids (−)-ephedrine, (+)-pseudoephedrine, and (±)-norephedrine, either singly or in mixtures with each other. Determination of individual alkaloids was carried out in D2O solution, with acetamide as internal standard. Although calculations were based on integrals for the C–CH3 protons, those for the N–CH3 and –CH–O– protons may also be useful, depending on the compound. Determination of diastereomeric cross-contamination of ephedrine and pseudoephedrine—or of the concentrations of these alkaloids in the presence or absence of (±)-norephedrine—was feasible by using the integrals for the –CH–O– protons after addition of a trace of DCI. Mean recoveries for ephedrine and pseudoephedrine from their respective synthetic mixtures with the internal standard (acet- amide) were ≥99.9 ± 0.6% (n = 10) and 99.6 ± 0.8% (n = 10) of the amount added. Recovery for pseudoephedrine from diastereomeric mixtures with ephedrine was >99.4 ± 0.7% (n = 10) of the amount added, with as little as 1.92% still being measurable. Mean recovery of (±)-norephedrine from mixtures with ephedrine and pseudoephedrine was >99.7 ± 2.5% (n = 4) of the amount added, with about 1% still being measurable. Application of the proposed NMR spectroscopic method to commercial dosage forms, including ephedrine sulfate injections and pseudoephedrine hydrochloride tablets, yielded assay results ranging from 97.8 to 100.2% (mean, 99.2%) and from 98.7 to 100.5% (mean, 99.7%) of declared, respectively.

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