Zur Thermodynamik der hydrophoben Wechselwirkung; die Systeme Wasser + Glycin+ Harnstoff und Wasser + Alanin+ Harnstoff bei 25 °C / Thermodynamics of Hydrophobie Interaction in the Systems Water + Glycin + Urea and Water + Alanin + Urea at 25 °C

1973 ◽  
Vol 28 (9-10) ◽  
pp. 533-554 ◽  
Author(s):  
Lothar Rafflenbeul ◽  
Wa-Ming Pang ◽  
Hansjürgen Schönert ◽  
Klaus Haberle
Keyword(s):  
Amino Acid ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Pressure Measurements ◽  
Free Enthalpy ◽  
Heat Of Dilution ◽  
Ternary Solutions ◽  
Vapor Pressure Measurements ◽  
Calorimetric Determination

Abstract Isopiestic vapor pressure measurements and calorimetric determination of the heat of dilution have been performed and evaluated with respect to enthalpy, entropy and free enthalpy in the ternary solutions water+ glycin+ urea and water+ alanin + urea. The free enthalpy of transfer for the process: Amino acid from water to water+ urea, which can be derived from these measurements, does not agree with the value calculated from solubility measurements. The reason for this discrepancy and the values of entropy and enthalpy in terms of hydrophobic interaction are discussed. Supplementary measurements of the proton magnetic resonance in these solutions are included.

Proton Magnetic Resonance Spectroscopic Method for Determination of Phenylbutazone and Oxyphenbutazone in Tablets

1988 ◽  
Vol 71 (3) ◽  
pp. 525-527
Author(s):  
Sajid Husain ◽  
M Kifayatullah ◽  
R NAGESWARA RAO
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Spectroscopic Method ◽  
Internal Standard ◽  
Aromatic Proton ◽  
British Pharmacopoeia ◽  
Standard Deviations ◽  
Proton Resonances

Abstract A simple, specific, and rapid 'H nuclear magnetic resonance spectroscopic method for the assay of phenylbutazone and oxyphenbutazone is described. Spectra are recorded in CDC13 containing 1,3- dichloro-5-nitrobenzene as an internal standard. The aromatic proton resonances for the standard, at 57.7 and 8.2, are well separated from those of phenylbutazone and oxyphenbutazone, which are in the region of 56.5-7.3 ppm. Average percent recoveries of phenylbutazone and oxyphenbutazone were 98.9 and 98.6 with standard deviations of 0.6 and 0.7, respectively. Commercial formulations were analyzed and the results obtained by the proposed method closely agreed with those found by the British Pharmacopoeia method

Proton Magnetic Resonance Spectroscopic Determination of Disulfiram: Collaborative Study

1978 ◽  
Vol 61 (1) ◽  
pp. 55-59
Author(s):  
Eric B Sheinin ◽  
Walter R Benson
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Drug Product ◽  
Spectroscopic Method ◽  
Collaborative Study ◽  
Internal Standard ◽  
Spectroscopic Determination ◽  
Standard Deviations ◽  
Bulk Drug

Abstract A proton magnetic resonance spectroscopic method for determining disulfiram in the bulk drug product and in the formulated material was collaboratively studied. The method depends on the use of chloroform-d as a solvent and hexamethylcyclotrisiloxane as the internal standard. No interference from tablet excipients was observed. The method is rapid and specific. Eighteen laboratories analyzed duplicate samples of a bulk drug product, a 250 mg tablet composite, and a 500 mg tablet composite. The average per cent results and standard deviations were 99.7±1.4, 100.9±2.0, and 99.9±2.2, respectively.

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