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971.
The Ilkovi? constant was determined for zinc and zinc—amino acid complexes by using differential pulse polarography in 0.1 M sodium chloride—sodium diethylbarbiturate buffer at pH 7.4. A single well-behaved wave was obtained, except for cysteine and cystine for which useful calibration curves could not be obtained. The non-equilibrium dialysis of the amino acid complexes was studied in a hollow-fiber dialyzer. It is concluded that the dialysis step could be used in a method intended to measure available zinc but that the polarographic method needs further modification. 相似文献
972.
Markos M. Papadakis Sonia P. Martins Hugh W. Thompson Roger A. Lalancette 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):o321-o322
The ring system of the title compound, C13H18O3, was synthesized by addition of ethyl acrylate to the dienamine of 2‐octalone. The keto acid aggregates in the solid as acid‐to‐acid dimers [O?O = 2.663 (2) Å and O—H?O = 170 (3)°] whose centrosymmetric hydrogen bonds lie across the a edges and the center of the chosen cell. Three intermolecular C—H?O close contacts within 2.7 Å were found involving the ketone group. 相似文献
973.
Carlos E.?Cardoso Renata O. R.?Martins Cláudia A. S.?Telles Ricardo Q.?AucélioEmail author 《Mikrochimica acta》2004,146(1):79-84
The study describes a simple and sensitive method for the sequential determination of hydrocortisone (HDC) and epinephrine (EP) in pharmaceutical formulations. The intrinsic fluorescence of epinephrine was measured before submitting the sample to a photochemical reaction to form a fluorescent product from HDC or HDC esters (succinate and acetate). The sample treatment eliminated the fluorescence from EP, thus minimizing spectral interference on the HDC fluorescence. Limits of detection (3Sb/m) were estimated to be 40ngmL–1 for HDC or HDC salts and 0.2ngmL–1 for EP. Recovery experiments, made with commercial and laboratory simulated formulations, gave values between 96 and 103% for both HDC and EP. This method can be easily automated, e.g. via flow-injection techniques. 相似文献
974.
Martins FJ Viljoen AM Kruger HG Wessels PL 《Magnetic resonance in chemistry : MRC》2004,42(4):402-408
NMR techniques cannot unambiguously distinguish between 11-amino-8-hydroxypentacyclo[5.4.0.0(2, 6).0(3, 10).0(5, 9)]undecane-8,11-lactam and 8-amino-11-hydroxypentacyclo[5.4.0.0(2, 6).0(3, 10).0(5, 9)]undecane-8,11-lactam, both of which are possible products during the reaction of pentacyclo[5.4.0.0(2, 6).0(3, 10).0(5, 9)]undecane-8,11-dione with Strecker reagents. Treatment of 11-amino-8-hydroxy-pentacyclo[5.4.0.0(2, 6).0(3, 10).0(5, 9)]undecane-8,11-lactam with acetic anhydride at room temperature produced a monoacetate. With acetic anhydride containing sodium acetate, a triacetate was obtained at reflux temperature. Treatment with acetyl chloride and N,N-dimethylaniline produced a diacetate. High-field 1H and 13C NMR techniques were used in the structure elucidation and assignment of the different NMR resonances of these three acetylated compounds. 相似文献
975.
Single-phase solutions (1.72 x 10(-2)M in TTA) of water/ethanol/MIBK, when added to an excess of water, break down into two immiscible liquid layers and TTA complexes of Fe(III), Co(II), Ni(II), Cu(II) and PB(II) are extracted into the organic layer. Quantitative extractions were obtained for the five metals and separations of Fe(III) from a 1000-fold excess of Co(II), NI(II) or PB(II) are obtained. The reactions of the metal ions with TTA were studied in the single-phase solutions before the extraction step, giving useful information as to their complexation behavior. 相似文献
976.
The synthesis of 2-amino-7,8-dihydrobenzo[1,2]cyclohepta[3,4,5-de]quinazoline ( 10 ) and 6,7-dihydrobenzo[1,2]cyclohepta[3,4,5-cd]indazole ( 5 ) is described. 相似文献
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980.