Stability indicating HPLC method for the simultaneous determination of moxifloxacin and prednisolone in pharmaceutical formulations

ABSTRACT: BACKGROUND: A simple, specific, and fast stability indicating reverse phase liquid chromatographic method was established for instantaneous determination of moxifloxacin and prednisolone in bulk drugs and pharmaceutical formulations. RESULTS: Optimum chromatographic separations among the moxifloxacin, prednisolone and stressinduced degradation products were achieved within 10 minutes by use of BDS Hypersil C8 column (250 X 4.6 mm, 5 mum) as stationary phase with mobile phase consisted of a mixture of phosphate buffer (18 mM) containing 0.1% (v/v) triethylamine, at pH 2.8 (adjusted with dilute phosphoric acid) and methanol (38:62 v/v) at a flow rate of 1.5 mL min-1. Detection was performed at 254 nm using diode array detector. The method was validated in accordance with ICH guidelines. Response was a linear function of concentrations over the range of 20-80 mug mL-1 for moxifloxacin (r2 [greater than or equal to] 0.998) and 40-160 mug mL-1 for prednisolone (r2 [greater than or equal to] 0.998). The method was resulted in good separation of both the analytes and degradation products with acceptable tailing and resolution. The peak purity index for both the analytes after all types of stress conditions was [greater than or equal to] 0.9999 indicated a complete separation of both the analyte peaks from degradation products. The method can therefore, be regarded as stabilityindicating. CONCLUSIONS: The developed method can be applied successfully for simultaneous determination of moxifloxacin and prednisolone in pharmaceutical formulations and their stability studies.     

Role of donor defects in stabilizing room temperature ferromagnetism in (Mn, Co) co-doped ZnO nanoparticles

We report the effects of co-doping ZnO with Co and Mn in an n-type environment on ferromagnetism (FM). Two sets of samples, Zn(0.95-x)Co(0.04)Mn(x)O (0.000 ≤ x ≤ 0.02) and Zn(0.95-y)Co(y)Mn(0.04)O (0.000 ≤ y ≤ 0.02), were synthesized by the chemical route with oxygen vacancies introduced via annealing in a forming gas (reducing the atmosphere). In addition to the magnetization, the particles were characterized by x-ray diffraction, diffuse reflectance spectroscopy and x-ray absorption near-edge emission spectroscopy. The Co and Mn ions were determined to be in the + 2 state in a tetrahedral symmetry, with no evidence of metallic Co or Mn. We find that while a purely Mn-doped sample exhibits weak FM at room temperature, the general effect of Mn as a co-dopant with Co, in an n-type environment, is to decrease the moment strongly. All of our results can be systematically explained within the context of defect mediated FM in these wide bandgap semiconductors, where the coincidence of the spin-split-impurity (defect) band states and the 3d states leads to the development of a net moment alongside the formation of spin polarons.     

A new fractional analytical approach via a modified Riemann–Liouville derivative

This work suggests a new analytical technique called the fractional homotopy perturbation method (FHPM) for solving fractional differential equations of any fractional order. This method is based on He’s homotopy perturbation method and the modified Riemann–Liouville derivative. The fractional differential equations are described in Jumarie’s sense. The results from introducing a modified Riemann–Liouville derivative in the cases studied show the high accuracy, simplicity and efficiency of the approach.     

Nonclassicality of two-mode nonorthogonal states

Nonclassical features of Schrödinger cat state with two-mode superposition state based on two coherent states π out of phase by fixing the relative phase equal to average photon number are discussed. Study of two-mode quadrature squeezing, oscillatory and sub-Poissonian photon statistics show that nonclassicality exists for these states. However, it is observed that the considered states do not violates the Cauchy–Schwarz inequality. Furthermore, simultaneously existence of quadrature squeezing and sub-Poissonian photon statistics shows that these states have more nonclassical features than that of famous even and odd coherent states.     

Vibration characteristics of FGM circular cylindrical shells filled with fluid using wave propagation approach

The vibration characteristics of a functionally graded material circular cylindrical shell filled with fluid are examined with a wave propagation approach. The shell is filled with an incompressible non-viscous fluid. Axial modal dependence is approximated by exponential functions. A theoretical study of shell vibration frequencies is analyzed for simply supported-simply supported, clamped-simply supported, and clamped-clamped boundary conditions with the fluid effect. The validity and the accuracy of the present method are confirmed by comparing the present results with those available in the literature. Good agreement is observed between the two sets of results.     

Vibrations of FGM thin cylindrical shells with exponential volume fraction law

In this paper, the influence of an exponential volume fraction law on the vibration frequencies of thin functionally graded cylindrical shells is studied. Material properties in the shell thickness direction are graded in accordance with the exponential law. Expressions for the strain-displacement and curvature-displacement relationships are taken from Love＇s thin shell theory. The Rayleigh-Ritz approach is used to derive the shell eigenfrequency equation. Axial modal dependence is assumed in the characteristic beam functions. Natural frequencies of the shells are observed to be dependent on the constituent volume fractions. The results are compared with those available in the literature for the validity of the present methodology.     

Approximate partial Noether operators and first integrals for coupled nonlinear oscillators

Nonlinear Dynamics - We study the construction of approximate first integrals of approximate partial Euler–Lagrange equations via approximate partial Noether operators corresponding to a...     

Chemical sensing of Benzo[a]pyrene using Corchorus depressus fluorescent flavonoids

Plant phytochemicals, such as flavonoids are in use for the development of optical biosensor. Benzo[a]pyrene (B[a]P), is a pervasive environmental and dietary carcinogen. A fluorescent assay is developed using plant isolated flavonoid for the detection of B[a]P. High content saponins are excluded from the flavonoid-containing methanolic extract of Corchorus depressus by implying reduction of silver ions by saponins resulting in formation of silver nanoparticles. Isolated plant flavonoids are used to develop a spectrofluorometric assay for the detection of B[a]P. Decrease in the flavonoid fluorescence intensity by B[a]P is found to be based on both static and dynamic quenching. Specificity of the assay for B[a]P was tested for other carcinogens belonging to different classes of compounds. Flavonoids-mediated sensing can be implied for the development of new generation of nanoparticle-based biosensors that can be more sensitive and less susceptible to external factors, such as temperature and humidity.     

Heterotelechelic Polymers by Ring‐Opening Metathesis and Regioselective Chain Transfer

Heterotelechelic polymers were synthesized by a kinetic telechelic ring‐opening metathesis polymerization method relying on the regioselective cross‐metathesis of the propagating Grubbs’ first‐generation catalyst with cinnamyl alcohol derivatives. This procedure allowed the synthesis of hetero‐bis‐end‐functional polymers in a one‐pot setup. The molecular weight of the polymers could be controlled by varying the ratio between cinnamyl alcohol derivatives and monomer. The end functional groups can be changed using different aromatically substituted cinnamyl alcohol derivatives. Different monomers were investigated and the presence of the functional groups was shown by NMR spectroscopy and MALDI‐ToF mass spectrometry. Labeling experiments with dyes were conducted to demonstrate the orthogonal addressability of both chain ends of the heterotelechelic polymers obtained.