Correlation of isomer shift and quadrupole splitting and the sign of EFG

Mössbauer isomer shift // and quadrupole splitting /E_Q/ values in a series of isostructural compounds correlate well to give linear relationship provided the sign of electric field gradient /EFG/ is assigned to the E_Q. The correlation has been used in predicting the sign of EFG for some monosubstituted pentacyanoferrate/II/ complexes. Usefulness of such correlations and its limitations are presented.     

Effect of outer cations and water of crystallization on the radiolytic decomposition of nitrates

The -ray induced decomposition of several inorganic nitrates CsNO₃, TlNO₃, Mg/NO₃/₂.6H₂O, Ca/NO₃/₂.4H₂O, Hg/NO₃/₂, Hg/NO₃/₂.2H₂O, Pb/NO₃/₂ and Al/NO₃/₃.9H₂O has been studied at an absorbed dose of {5 Mrads. G/NO ₂ ^– / is affected by the outer cation and depends mainly on its valency and ionic size. G/NO ₂ ^– / for hydrated mercuric nitrate is always higher as compared to that for the anhydrous mercuric nitrate at various doses. Water of crystallization might provide extra factors to facilitate the decomposition of the hydrated nitrate compared to that for the anhydrous salts. In most cases G/NO ₂ ^– / decreases exponentially with dose but in cases of CsNO₃, Mg/NO₃/₂.6H₂O and Al/NO₃/₃.9H₂O it varies linearly.     

Study on gamma and electron beam sterilization of third generation cephalosporins cefdinir and cefixime in solid state

The effect of gamma radiation from ⁶⁰Co source and 2 MeV e-beam was studied on two thermolabile cephalosporin antibiotics viz cefdinir and cefixime in solid state. The parameters studied to assess radiolytic degradation were loss of chemical and microbiological potency, change in optical rotation, electronic and vibrational absorption characteristics, thermal behavior and color modification. ESR spectroscopic study, HPLC related impurity profile, thermogram and Raman spectrum are applied in deducing the nature of radiolytic impurities and their formation hypotheses. Cefixime is radiation sensitive, whereas cefdinir has acceptable radiation resistance at 25 kGy dose. The nature of radiolytic related impurities and their concentrations indicates that the lactam ring is not highly susceptible to direct radiation attack, which otherwise is considered very sensitive to stress (thermal, chemical and photochemical).     

Thin-Layer Chromatographic Selective and Stability-Indicating Method for Assay of Cefixime in Pharmaceuticals

JPC – Journal of Planar Chromatography – Modern TLC - A thin-layer chromatographic (TLC) method is developed for the analysis of cefixime using precoated silica gel 60F254 TLC aluminum...     

Thermodynamic and optical studies of some ethylene glycol ethers in aqueous solutions at T = 298.15 K

Experimental results of density (ρ), speed of sound (u), and refractive index (n_D) have been obtained for aqueous solutions of ethylene glycol monomethyl ether (EGMME), ethylene glycol monoethyl ether (EGMEE), diethylene glycol monomethyl ether (DEGMME), and diethylene glycol monoethyl ether (DEGMEE) over the entire concentration range at T = 298.15 K. From these measurements, the derived parameters, apparent molar volume of solute (?_V), excess molar volume (V^E), isentropic compressibility of solution (β_S), apparent molar isentropic compressibility of solute (?_KS), deviation in isentropic compressibility (Δβ_S), molar refraction [R]_1,2 and deviation in refractive index of solution (Δn_D) have been calculated. The Redlich–Kister equation has been fitted to the calculated values of V^E, Δβ_S and Δn_D for the solution. The results obtained are interpreted in terms of hydrogen bonding and various interactions among solute and solvent molecules.