Novel copolymers of vinyl acetate and dialkylfumarates, poly(VA-co-DRF) with R = isopropyl (DIPF) or octan-2-yl (DOF), were synthesized by radical copolymerization under microwave conditions. The products were characterized by (1)H NMR and FTIR spectroscopies, size exclusion chromatography and differential scanning calorimetry. Based on these copolymers three membranes supported on polyvinyl alcohol were prepared and their morphology, swelling and mechanical properties were studied. The swelling kinetic was analyzed and interpreted in light of the Fick transport model, showing that the water transport occurs through a non-Fickian diffusion mechanism. The results show that the membrane prepared of poly(VA-co-DOF) exhibited excellent properties as potential platform for transdermal delivery system: they exhibited good tensile strength, moderated swelling and form thin and transparent films.
The present work demonstrates that it is possible to obtain the parameters Kand a of the Staudinger-Mark-Houwink relationship between the intrinsicviscosity [q] and the molecularweight Mof a polymer by applying the absolute method of exclusion chromatographyto samples of poly(diisopropy1 fumarate).The procedure is based on deducing the relationship between molecular weight and elution volume V from chromatographic runs of a stoichiometrically labeled polymer sample with a broad molecular weight distribution. By using double detection it is possible to obtain the relationship f(V)/h(V) =M(V)/M, =exp (A-5V)/Mn where M,, is the osmotically determined number average of the molecular weight oftheeluted polymerwhile f(ll)and h(V)arethenormalized elution curves obtained by the use of the polymer mass detector and the label detector respectively. A and 5 are the parameters of the calibration curve, Le., the relationship between M and V which togetherwith the intrinsicviscosity and the elution curves of several samples of the polymer allows us to obtain the relationship between [q] and M.The results have beenverified with chromatographic data through the use of the universal calibration concept.
A micellar-stabilized room-temperature phosphorescence (MS-RTP) method for the determination of atenolol has been developed in micellar solutions of sodium dodecylsulphate (SDS) in the presence of thallium(I) as a heavy atom and sodium sulphite as an oxygen scavenger. The effects of thallium(I) nitrate, SDS and sodium sulphite concentrations on atenolol MS-RTP intensity were studied. Optimized conditions to obtain maximum sensitivity were 0.015 mol/L thallium(I) nitrate, 0.1 mol/L SDS and 0.0075 mol/L sodium sulphite. The maximum phosphorescence signal was completely developed in 10 min and the intensity was measured at lambda(ex) = 272 nm and lambda(em) = 412 nm. The linear range of application obtained was 2.01-16.00 microg/mL. The detection limit estimated from the least-squares regression analysis was 0.86 microg/mL and the relative standard deviation of 10 replicates was 1.7%. The proposed method was applied to the determination of atenolol in a pharmaceutical formulation. The quantitation was carried out by means of standard calibration, standard-additions calibration and Youden calibration. These three experiments were necessary to evaluate the presence of constant and proportional errors due to the matrix.
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