Stability-Indicating HPLC Method for the Determination of Metadoxine as Bulk Drug and in Pharmaceutical Dosage Form

A sensitive and reproducible method is described for the quantitative determination of metadoxine in the presence of its degradation products. The method was based on high performance liquid chromatographic separation of the drug from its degradation products on the reversed phase, kromasil column [C₁₈ (5-micron, 25 cm × 4.6 mm, i.d.)] at ambient temperature using a mobile phase consisting of methanol and water (50: 50, v/v). Flow rate was 1.0 mL min^?1 with an average operating pressure of 180 kg cm^?2 and t _R was found to be 2.85 ± 0.05 min. Quantitation was achieved with UV detection at 286 nm based on peak area with linear calibration curves at concentration range 10–100 μg mL^?1. This method has been successively applied to pharmaceutical formulation. No chromatographic interference from the tablet excipients was found. The method was validated in terms of precision, robustness, recovery and limits of detection and quantitation. Drug was subjected to acid, alkali and neutral hydrolysis, oxidation, dry heat, wet heat treatment and photo and UV degradation. As the proposed method could effectively separate the drug from its degradation products, it can be employed as stability indicating one. Moreover, the proposed HPLC method was utilized to investigate the kinetics of the acidic, alkaline and oxidative degradation processes at different temperatures and their respective apparent pseudo first order rare constant, half-life and activation energy was calculated with the help of Arrhenius plot. In addition the pH-rate profile of degradation of metadoxine in constant ionic strength buffer solutions with in the pH range 2–11 was studied.     

Polarographic investigation of zinc phosphate precipitation process at trace level

Summary Polarography is attempted in the study, at trace level, of zinc phosphate precipitate which is not sparingly soluble. The choice of the supporting electrolyte is very important as it functions also as a coagulating agent. In contrast to conventional polarography, the supporting electrolyte concentration was found to be critical. The effect of p_H, temperature, volume, time, stirring, etc. was studied. Complete precipitation was obtained under proper conditions for 40g/ml of zinc solution.

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Zusammenfassung Das deutlich lösliche, in Spuren gefällte Zinkphosphat wurde polarographisch untersucht. Die Wahl des Trägerelektrolyten ist hierbei sehr ausschlaggebend, da er auch koagulationsfördernd wirkt. Im Gegensatz zur konventionellen Polarographie erwies sich die Konzentration des Trägerelektrolyten als kritisch. Der Einfluß des p_H, der Temperatur, des Volumens, der Zeit, des Rührens der Lösung usw. wurde untersucht. Unter geeigneten Bedingungen wurde die vollständige Fällung einer Lösung von 40g Zn/ml erreicht.

     

Crystal and molecular structure of 12(S)-acetoxy-4(S),8(R)-dimethyl-3-oxo-1(R)-5(S)-9(S)-2-oxatricyclo[4.4.7.01,9.3.4.8.01,5]tridecane

The structure of the title compound, a cyclic ether acetate lactone, has been established uniquely by X-ray crystallography. C₁₆H₂₄O₄ is orthorhombic, space groupP2₁2₁2₁, with the cell dimensionsa=7.524(2),b=10.686(2),c=19.472(2) Å,V=1565.6(4) ų,Z=4,M _r=280.4,D _x=1.19 g cm^–3,D _o=1.20 g cm^–3,F(000)=608,T=293 K, finalR=0.050. The two cyclohexane ring junction iscis while the lactone ring junction istrans. Both the cyclohexane rings have the chair conformation and the -lactone ring has an envelope conformation with C(7) being at the tip of the flap. The acetoxy side chain is-equatorial. There is an intramolecular C-H---O interaction C(4)O(4)=2.666(4) Å.N. C. L. Communication No. 5064.     

The structure of β-(2)-nitrophenyl acrylonitrile

The structure of an important intermediate, IUPAC name: 2-(2-nitrophenyl) acrylonitrile has been studied by X-ray crystallography. C₉H₆N₂O₂ is monoclinic, space groupP2_1/c with cell dimensionsa=7.045(1),b=10.011(1),c=12.016(1) Å,=97.88(1)°,V=839.5(2) ų,Z=4,M _r =174.30,D ₀=1-38(1),D _x =1.39(1) g cm^–3,F(000)=360,T=293 K, (CuK)=1.5418 Å,=8.00 cm^–1,R=0.034 for 987 observed reflections. The aromatic ring is nearly planar. The Nitro group is rotated out of the aromatic plane by 26.5(1)°. There are three C-HO[3.469(3), 3.245(3), and 3.440(3) Å] and one C-HN[3.561(3) Å] intermolecular interaction.N.C.L. Communication No. 4847.     

RESTRICTED LIE ALGEBRAS WITH MAXIMAL 0-PIM

In this paper it is shown that the projective cover of the trivial irreducible module of a finite-dimensional solvable restricted Lie algebra is induced from the one dimensional trivial module of a maximal torus. As a consequence, the number of the isomorphism classes of irreducible modules with a fixed p-character for a finite-dimensional solvable restricted Lie algebra L is bounded above by p ^MT(L), where MT(L) denotes the maximal dimension of a torus in L. Finally, it is proved that in characteristic p > 3 the projective cover of the trivial irreducible L-module is induced from the one-dimensional trivial module of a torus of maximal dimension, only if L is solvable.