Authors:P. S. Jain, A. J. Chaudhari, and S. J. Surana
A simple, selective, precise, and stability-indicating high-performance thinlayer chromatographic method for analysis of sitagliptin phosphate both in a bulk and in pharmaceutical formulation has been developed and validated. The method employed high-performance thin-layer chromatography (HPTLC) aluminium plates precoated with silica gel 60 RP-18 F254 as the stationary phase. The solvent system consisted of methanol-water-triethylamine (8:2:0.05 v/v). The system was found to give compact spot for sitagliptin phosphate (Rf value of 0.55 ± 0.03). Densitometric analysis of sitagliptin phosphate was carried out in the absorbance mode at 267 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r2 = 0.998±0.0015 with respect to peak area in the concentration range 1000–6000 ng per spot. The mean value ± SD of slope and intercept was 0.723 ± 0.043 and 17.24 ± 18.78 with respect to peak area. The method was validated for precision, recovery, and robustness. The limits of detection and quantification were 85.80 and 265.42 ng per spot, respectively. Sitagliptin phosphate was subjected to acid and alkali hydrolysis, oxidation, and photo and thermal degradation. The drug undergoes degradation under acidic, basic, and oxidative conditions. This indicates that the drug is susceptible to acid and base, and oxidation. The degraded product was well resolved from the pure drug with significantly different RF value. Statistical analysis proves that the method is repeatable, selective, and accurate for the estimation of investigated drug. The proposed developed HPTLC method can be applied for identification and quantitative determination of sitagliptin phosphate in bulk drug and pharmaceutical formulation.
Authors:C. V. Chaudhari, Y. K. Bhardwaj, and S. Sabharwal
Grafting ofmethyl methacrylate (MMA) on radiation crosslinked natural rubber (NR) film has been investigated by mutual radiation
grafting. The effect of experimental parameters like radiation dose, dose-rate, additives like acids and inorganic salts,
solvents, monomer concentration, cross-linking density of the natural rubber film on the grafting extent has been studied.From
the kinetic studies, a kinetic equation showing almost parabolic and linear dependence of grafting on concentration and dose
rate, respectively, was deduced.Preliminary thermal stability studies of grafted films indicated that grafting of MMA does
not enhance the thermal stability of NR.
Authors:S. Obayd, B. Rao, S. Bendre, R. Viswanathan, S. Chaudhari, S. Kanetkar, and S. Ogale
High-Tc superconductor YBa2Cu3O7 was irradiated by thermal neutrons. Significant effects on the critical temperature were found. The changes were also investigated by X-ray diffraction technique.65Cu (n, )66Cu was the only reason for the degradation in superconducting properties. The existence of an isotope effect is argued.
Authors:C. Chaudhari, K. Dubey, Y. Bhardwaj, Virendra Kumar, N. Goel, and S. Sabharwal
Radiation induced grafting of acrylonitrile (ACN) on ethylene-propene diene terpolymer (EPDM) rubber film was investigated
by mutual radiation grafting technique. Effect of experimental variables viz. radiation dose, dose rate, type of solvent and
monomer content on extent of grafting was studied. From the kinetic studies a mathematical relation Rgα[M]0.7D0.68 showing non-linear relationship for rate of grafting with monomer concentration and dose was deduced. The grafted samples
showed increased hardness and oil resistance.