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The transport of chloroform in films of atactic polystyrene and of semicrystalline syndiotactic polystyrene in its nanoporous form (δ‐form) has been investigated by gravimetric analysis. Experimental tests have been performed at 35, 49, and 56 °C and at several vapor pressures ranging from 0.5 to 100 Torr. Nonequilibrium lattice fluid prediction of the amorphous sorption behavior was used to enucleate the sorption contribution of the crystalline nanoporous phase from semicrystalline samples. Sorption behavior of the crystalline phase has been interpreted on the basis of Langmuir equation. Moreover, the chloroform sorption at low activities in the crystalline nanoporous phase has been predicted by using Grand Canonical Monte Carlo molecular simulations. Isosteric heats of sorption were also experimentally evaluated for the crystalline phase, and compared with the corresponding prediction of molecular simulation. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 8–15, 2008  相似文献   
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A mixed‐polymeric electrokinetic chromatography system has been developed for the simultaneous determination of a contaminant like oversulfated condroitin sulfate (OSCS) and impurities expressed as dermatan (Der) in heparin (Hep) samples. The EKC system consisted of 0.5% w/v polymeric β‐CD, 0.4% w/v tetronic® 1107 and 400 mM tris‐phosphate buffer at pH 3.5. The optimized electrophoretic conditions included the use of an uncoated‐silica capillary of 50 cm of total length and 75 μm id, an applied voltage of ?7 kV, a temperature of 30°C and 200 nm UV‐detection. The highly sensitive method developed showed low values of LOD, 0.07% w/w (0.07 μg/mL) (OSCS) and 0.1% w/w (0.1 μg/mL) (Der), and values of LOQ 0.2% w/w (0.2 μg/mL) (OSCS) and 0.3% w/w (0.3 μg/mL) (Der) with a concentration level of Hep sample as low as 0.1 mg/mL. Additional parameters of validation such as specificity, linearity, accuracy, and robustness were evaluated according to international guidelines. Owing to its simplicity, high sensitivity, and reliability, the proposed method can be an advantageous alternative to the traditional methodologies for the analysis of Hep in raw material and specially in finished products because of the low amounts of Hep sample required.  相似文献   
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