Determination of Meloxicam Using Europium Sensitized Luminescence in the Presence of Co-Luminescence Reagents

A sensitive time- resolved luminescence method for the determination of meloxicam (MX) in methanol and in aqueous solution is described. The method is based on the luminescence sensitization of europium (Eu³⁺) by formation of ternary complex with MX in the presence of 1,10- phenanthroline as coligand, Tween-80 as surfactant and gadolinium ion as a co-luminescence reagent. The signal for Eu- MX-1, 10- phenanthroline is monitored at λ_ex = 360 nm and λ_em = 620 nm. Optimum conditions for the formation of the complex in aqueous system were 0.01 M TRIS buffer, pH 8.0, 1,10- phenanthroline (6.0 × 10⁻⁶ M) , Gd³⁺ (7.0 × 10⁻⁶ M), Tween-80 (0.28%) and 1.75 mM of Eu³⁺ which allows the determination of 20–800 ppb of MX with limit of detection (LOD) of 7 ppb. The relative standard deviations of the method range between 0.1 and 1.1% indicating excellent reproducibility of the method. The proposed method was successfully applied for the assay of MX in pharmaceutical formulations, plasma and in urine samples. Average recoveries of 99.8 ± 1.1%, 100.2 ± 0.9% and 100.9 ± 1.1% were obtained for MX in tablet, plasma and urine sample respectively.     

Physical aging phenomena in silica and glass beads filled elastomers (EPDM)

The physical aging concept is generally used to explain the typical behavior of amorphous glassy materials such as amorphous polymers. It can be easily evidenced by measuring the effect of a static deformation on the dynamic mechanical properties. In this paper, an attempt is made to determine the “glassy” behavior of elastomeric EPDM chains when they are confined in the vicinity of the filler (glass beads, silicas) surface. It is demonstrated that glassy behavior and physical aging phenomena are detected even with a filled elastomer. Furthermore, the influence of the filler volume fraction, the filler nature and of filler surface treatments with silanes were studied. Finally, an original attempt is made to explain filler-rubber reinforcement by a kind of bimodal network created from linkages between a densely packed interfacial region and the outer loose matrix.     

Synthesis and properties of segmented poly(hydroxyether-siloxane)

Segmented or block poly(hydroxyether-siloxane) copolymers were synthesized by both a monomer-oligomer or an oligomer-oligomer synthetic approach. Perfectly alternating sequence distributions were obtained from the monomer or oligomer(s) bearing mutually reactive end groups, and the hydroxyether linkages are formed simultaneously with the growth of the second block. Differential scanning calorimetry (DSC), Dynamic Mechanical Thermal Analyzer (DMTA), and small angle X-ray scattering (SAXS) results indicated that microphase separated morphologies were achieved for each of the copolymers, even those structures synthesized by the monomer-oligomer route. The mechanical properties of the networks ranged from a rubber toughened thermoplastic to a thermoplastic elastomer and depended on which phase was predominantly continuous.