Thermal behaviour of the
glass series (100–y)[0.5ZnO0.1B2O30.4P2O5]yTiO2
(with y=0–39 mol% TiO2)
was investigated by DSC and TMA. The addition of TiO2
results in a non-linear increase of glass transition temperature. The compositional
dependences of thermal stability, evaluated by two criteria exhibit two maxima
for the glasses doped with 10.7 and 35.9 mol% TiO2.
All the glasses crystallize on heating in the temperature range of 576–670C.
The crystallization mechanism was studied at the glasses with 19.4 and 35.9
mol% TiO2 and the results showed that surface nucleation
mechanism prevails in these glasses over the internal one.
The study of homogeneous distribution coefficients in determining the transition temperatures of isomorphologically analogous
components and in predicting the existences of some new unstable compounds has been carried out in detail with special references
to vitriols of nickel, manganese, zinc, copper and magnesium. In the course of the investigation with NiSO4·7H2O as host and54Mn as guest, the transition temperature of orthorhombic NiSO4·7H2O was shown to be 26.5 °C, and with orthorhombic ZnSO4·7H2O and MgSO4·7H2O as host and copper sulphate as guest, the limits of existences of orthorhombic CuSO4·7H2O and newly predicted CuSO4·6H2O were found to be 13.5° to 44 °C and 44° to 51 °C, respectively. In addition, the transition temperatures of orthorhombic
MnSO4·7H2O (10 °C), stable NiSO4·7H2O (30.5±5 °C) and orthorhombic ZnSO4·7H2O (39 °C) were verified. The new method of approach is very simple, reproducible and easily adaptable.
A simple, sensitive, and stability-indicating high-performance thinlayer chromatography (HPTLC)-densitometric method was developed for the quantification of biomarker naringin in the methanol extracts of stems and leaves of Rumex vesicarius. Chromatography was performed on glass-backed silica gel 60 F254 high-performance thin-layer chromatography (HPTLC) plates with ethyl acetateglacial acetic acid-MeOH-H2O (30:10:5:1, ½/½) as mobile phase. Scanning and quantification were done at 275 nm. The system was found to give compact spot for naringin at RF = 0.46 ± 0.001. The linear regression analysis data for the calibration plots showed good linear relationship with r2 = 0.998 with respect to area in the concentration range of 100–1000 ng. The regression equation of standard was found to be Y = 3.438X + 38.485. Naringin was subjected to acid and alkali hydrolysis, peroxide oxidation, photodegradation, dry heat, moist heat, and ultraviolet (UV) treatment. The drug undergoes complete degradation under acidic treatment and mild degradation under basic and hydrogen peroxide treatment. The degraded products were well-separated from the pure drug. The statistical analysis proves that the developed method for quantification of naringin is reproducible and selective. Due to the ability of the method in separating naringin from other constituents including its degradation products, it can be employed as stability-indicating method for in-process as well as finished products in the market. It is for the first time that authors are reporting a complete stability-indicating densitometric HPTLC method for the estimation of biomarker naringin in the leaves and stems of R. vesicarius L.
Authors:Christian Vogel, Christian Adam, and Miriam Unger
nearly constant mass loss was observed in the range 400–1000 °C.
TG/DTA diagram for a mixture of SSA and MgCl 2 ·6H 2 O; 30–1000 °C with 5 °C/min afterwards 30 min isotherm segment at 1000 °C (TG
Authors:Justyna Sułowska, Irena Wacławska, and Magdalena Szumera
)Na 2 O– x CuO–(50− x /2)P 2 O 5 system, where x is less than 34 mol% [ 1 ], as well as glasses from 50P 2 O 5 –20Na 2 O–30CuO system [ 2 ] were totally amorphous. For glasses from P 2 O 5 –Na 2 O–CuO system the glass formation region was determined