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

1996 ◽  
Vol 79 (4) ◽  
pp. 833-838 ◽  
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.

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

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1599
Author(s):  
Hsin-Yi Hung ◽  
Shih-Min Lin ◽  
Chia-Ying Li ◽  
Sio-Hong Lam ◽  
Yu-Yi Chan ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
1H Nmr ◽  
Present Method ◽  
Internal Standard ◽  
Proton Nuclear Magnetic Resonance ◽  
Nmr Spectrum ◽  
Herbal Preparations ◽  
Nmr Method ◽  
Quantification Method ◽  
Preliminary Purification

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.

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

Molecules ◽  
2018 ◽  
Vol 23 (7) ◽  
pp. 1785 ◽  
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.

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

1995 ◽  
Vol 78 (2) ◽  
pp. 353-357 ◽  
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.

1H NMR Spectroscopic Method with Chiral Eu(III) Shift Reagent for the Determination of the Enantiomeric Composition of Naproxen

1992 ◽  
Vol 75 (3) ◽  
pp. 417-422 ◽  
Author(s):  
George M Hanna ◽  
Cesar A Lau-Cam
Keyword(s):  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Methyl Esters ◽  
Spectroscopic Method ◽  
Shift Reagent ◽  
Simple Method ◽  
Nmr Spectrum ◽  
Lanthanide Ion ◽  
Diastereomeric Complexes

Abstract A simple method based on the use of 1H NMR spectroscopy with chiral Eu(lll) shift reagent is described for the determination of (S)-(+)- and (R)-(-)-naproxen In the presence of each other. To enhance the coordinating affinity of the substrate for the lanthanide Ion, the sample was first derivatized to a mixture of methyl esters, which in the presence of Eu(hfc)3 formed short-lived diastereomeric complexes with sufficient nonequivalency In the 1H NMR spectrum. Optimum complexing conditions corresponded to concentrations of substrate and Eu(hfc)3 of 0.1 M each in CDCI3. In this matter, the enantiomeric ester-methyl protons and α-methyl protons yielded well-resolved resonance signals of utility in the measurement of enantiomeric compositions. Recovery studies demonstrated that the proposed method Is quantitative.

Nuclear Magnetic Resonance Spectroscopic Determination of Methoxyflurane

1981 ◽  
Vol 64 (5) ◽  
pp. 1154-1157
Author(s):  
Kermit W Henry
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Carbon Tetrachloride ◽  
Magnetic Resonance ◽  
Dimethyl Sulfoxide ◽  
Spectroscopic Method ◽  
Proton Nmr ◽  
Internal Standard ◽  
Nmr Spectrum ◽  
Nuclear Magnetic

Abstract A simple, rapid nuclear magnetic resonance (NMR) spectroscopic method for quantitatively determining methoxyflurane was developed. The proton NMR spectrum of methoxyflurane in carbon tetrachloride exhibited a well defined triplet at 5.67 ppm and a sharp singlet at 3.68 ppm. Using dimethyl sulfoxide (DMSO) as an internal standard, methoxyflurane was quantitated by comparing the integral for the singlet of methoxyflurane with the integral for the singlet of DMSO at 2.60 ppm. The method was accurate to concentrations as low as 1‑2%, and results agreed with those obtained by the NF XIV method

Nuclear Magnetic Resonance Analysis of Pharmaceuticals. XIII. Carbromal and Bromural in Tablets

1974 ◽  
Vol 57 (4) ◽  
pp. 893-896
Author(s):  
John W Turczan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Quantitative Analysis ◽  
Standard Deviation ◽  
Magnetic Resonance ◽  
Internal Standard ◽  
Solvent Mixture ◽  
Nuclear Magnetic Resonance Analysis ◽  
Nmr Spectrum ◽  
Resonance Analysis ◽  
Nuclear Magnetic

Abstract A new procedure for a rapid quantitative analysis of carbromal and bromural in tablets is described. The method is based on measurement of the nuclear magnetic resonance (NMR) signal of each compound in a carbon tetrachloride- pyridine solvent mixture (2+1), with hexamethylcyclotrisiloxane as an internal standard. A standard deviation of 0.7% for carbromal and 0.5% for bromural was obtained on synthetic mixtures. The NMR spectrum provides a specific means of identification for these 2 compounds.

Determination of alcohols in mixtures by 19F NMR spectroscopy using hexefluoroacetone reagent

1982 ◽  
Vol 47 (7) ◽  
pp. 1973-1978 ◽  
Author(s):  
Jiří Karhan ◽  
Zbyněk Ksandr ◽  
Jiřina Vlková ◽  
Věra Špatná
Keyword(s):  
Standard Deviation ◽  
Nmr Spectroscopy ◽  
Standard Method ◽  
Internal Standard ◽  
Internal Standard Method ◽  
Concentration Region ◽  
Experimental Conditions ◽  
Curve Method ◽  
Sample Preparation Procedure

The determination of alcohols by 19F NMR spectroscopy making use of their reaction with hexafluoroacetone giving rise to hemiacetals was studied on butanols. The calibration curve method and the internal standard method were used and the results were mutually compared. The effects of some experimental conditions, viz. the sample preparation procedure, concentration, spectrometer setting, and electronic integration, were investigated; the conditions, particularly the concentrations, proved to have a statistically significant effect on the results of determination. For the internal standard method, the standard deviation was 0.061 in the concentration region 0.032-0.74 mol l-1. The method was applied to a determination of alcohols in the distillation residue from an oxo synthesis.

Quantitative Determination of some Carbonate Minerals in Greenschist Facies Meta-volcanic Rocks

1972 ◽  
Vol 9 (1) ◽  
pp. 36-42 ◽  
Author(s):  
Calvert C. Bristol
Keyword(s):  
Standard Deviation ◽  
Quantitative Determination ◽  
Volcanic Rocks ◽  
Internal Standard ◽  
Greenschist Facies ◽  
Carbonate Mineral ◽  
Mineral Contents ◽  
X Ray ◽  
Fine Grained

X-ray powder diffraction methods, successful in quantitative determination of silicate minerals in fine-grained rocks, have been applied to the determination of calcite, dolomite, and magnesite in greenschist facies meta-volcanic rocks. Internal standard graphs employing two standards (NaCl and Mo) have been determined.Carbonate mineral modes (calcite and dolomite) for 6 greenschist facies meta-volcanic rocks obtained by the X-ray powder method have been compared to normative carbonate mineral contents calculated for the same rocks. This comparison showed a maximum variation of 7.7 wt.% between the X-ray modes and the normative carbonate mineral contents of the rocks. Maximum standard deviation for the X-ray modes of these rocks was equivalent to 4.4 wt.%.

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