Polarographic determination of loratadine in pharmaceutical preparations

Loratadine, a potent antihistamine drug, is not directly electroreducible at a dropping mercury electrode; however, by means of a nitration procedure it is possible to obtain a nitro-loratadine derivative which has been identified as 4-(8-chloro-7-nitro-5,6-dihydro-11 H-benzo-[5,6]-cyclohepta-[l,2-b]-pyridin-l l-ylidene)-1-piperidine carboxylic acid ethyl ester. The electrochemical reduction of this derivative at different pHs and concentrations using polarography and cyclic voltammetry was studied. The derivative exhibits a differential pulse polarographic peak due to the reduction of the nitro group. This peak was used in order to develop an analytical procedure for determining loratadine in pharmaceutical dosage forms.

The recovery study shows adequate accuracy and precision for the developed assay and the excipients do not interfere in the determination.     

Über Chalkogenolate. 94. Untersuchungen über Trithioallophansäure 3. Ester der Trithioallophansäure [1]

On Chalcogenolates. 94. Studies on Trithioallophanic Acid. 3. Esters of Trithioallophanic Acid. The esters of trithioallophanic acid H₂N? CS? NH? CS(SR) with R = CH₃, CH₂C₆H₅ have been characterized by means of electron absorption spectra, infrared spectra, ¹H NMR spectra, and mass spectra.     

1H and 13C NMR signal assignment of benzylisoquinoline alkaloids from Fumaria officinalis L. (Papaveraceae)

The NMR signal assignments of a series of structurally divergent benzylisoquinolines isolated from Fumaria officinalis L. (Fumariaceae, Papaverales), namely adlumine, corlumine, corydamine, cryptopine, fumarophycine, O-methylfumarophycine, hydrastine, parfumine, protopine and sinactine, are presented.     

Über Chalkogenolate. 135. Untersuchungen über Ester von Halogenoameisensäuren 3. Darstellung und Charakterisierung von Fluoro- und Bromothioameisensäurealkylestern

On Chalcogenolates. 135. Studies on Esters of Haloformic Acids. 3. Synthesis and Characterization of Alkyl Esters of Fluoro- and Bromothioformic Acid ⁿC₃H₇S? CO? F, C₂H₅S? CS? F, and ⁿC₃H₇S? CS? F have been prepared by reaction of the corresponding chloro compound with KF by use of phase transfer catalysts. The esters RS? CS? Br, where R ? C₂H₅ and ⁿC₃H₇, are formed by reaction between RSH and SCBr₂ in the presence of pyridine. The compounds have been characterized by means of diverse spectroscopic methods.     

Über Chalkogenolate. 137. Isothiocyano-, Isothiocyanomonothio- und Isothiocyanodithio- ameisensäurealkylester

On Chalcogenolates. 137. Alkyl Esters of Isothiocyanoformic, Isothiocyanomonothioformic and Isothiocyanodithioformic Acids The esters RO? CO? NCS, where R = CH₃, C₂H₅, as well as RS? CO? NCS and RS? CS? NCS with R = C₂H₅, ⁿC₃H₇ have been prepared by three different methods. The reaction between the corresponding chloro compound and KSCN in the presence of the phase transfer catalyst 18-crown-6 gives the highest yields. The electron absorption, infrared, nuclear magnetic resonance, and mass spectra of these compounds are reported.     

Isotopic composition of commercially available uranium chemicals and elemental analysis standards

Journal of Radioanalytical and Nuclear Chemistry - Reference information on isotopic composition of various uranium materials, determined with high accuracy and precision, is of essential value for...     

Modeling variations in near-infrared spectra caused by the coherent backscattering effect

We study a new optical effect, a spectral manifestation of coherent backscattering, which reveals itself as systematic variations in the depth of absorption bands with changing phase angle. We used Cassini VIMS near-infrared spectra of Saturn's icy satellite Rhea in order to identify and characterize the spectral change with phase angle, focusing on the change in the depth of water-ice absorption bands. To model realistic characteristics of the surfaces of icy satellites, which are most likely covered by micron-sized densely packed particles, we perform simulations using a theoretical approach based on direct computer solutions of the macroscopic Maxwell equations. Our results show that this approach can reproduce the observed phase-angle variations in the depth of the absorption bands. The modeled changes in the absorption bands are strongly affected by physical properties of the regolith, especially by the size and packing density of the ice particles. Thus, the phase-angle spectral variations demonstrate a promising remote-sensing capability for studying properties of the surfaces of icy bodies and other objects that exhibit a strong coherent backscattering effect.     

Untersuchung von Kakaoprodukten

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