This article describes a new, accurate and highly specific high performance liquid chromatographic method with UV detection (HPLC-UV) for the simultaneous determination of cetirizine HCl (CZ), chlorphenamine maleate (CPM), loratadine (LTD), domperidone (DP), buclizine (BZ) and meclizine (MZ) in pharmaceutical dosage form and human serum, involving pyridoxine (PYD) as the internal standard. The mobile phase consists of heptane sulphonic acid salt buffer and acetonitrile, drawn at a flow rate of 1.0 mL min À1 using a symmetry C 18 column with UV detection at 230 nm. The intraday and inter-day precision measurements showed coefficients of variation always less than one. The calibration curve was tested in the range of 10-2150 ng mL À1 and the correlation coefficient of >0.9990 in all cases was obtained. The averages of the absolute and relative recoveries were found to be in the range of 98 to 102%. Up to six antihistamines were separated in the same chromatogram with good resolution. The proposed HPLC method has reasonable applications in pharmaceutical tablet dosage form and pharmacokinetics studies.

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In this research, an optimal hydrogel, based on sulfonated polyacrylamide, was synthesized by statistical design of experiments using central composite method. This new hydrogel composed of sulfonated polyacrylamide (AN125VLM) and chromium triacetate as copolymer and crosslinker, respectively. The bottle and rheological tests were conducted to investigate the gelation time, thermal stability, gel strength and also ultimate elastic modulus, complex modulus, and yield stress. It was found that copolymer concentration had the main effect in both rheological and transport properties of hydrogels. The sample prepared at optimum condition, i.e. copolymer concentration of 26,340 ppm and crosslinker/copolymer ratio of 0.12, had an ultimate elastic modulus of 29.9 kPa, yield stress of 800 Pa, and complex modulus of 32 kPa. A coreflooding test through fracture was carried out to examine the optimum gel performance in a porous media. A value of 483 for the residual resistance factor ratio of water to oil confirmed the high ability of the hydrogel in reducing the relative permeability of water to oil in fractured media.

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One of the unique properties of hydrogels is the dramatically change in their volume and shape. In this research, conventional hydrogels (composed of sulfonated polyacrylamide and Cr(OAc) 3 as copolymer and crosslinker, respectively) were investigated versus nanocomposite (NC) hydrogels for the purpose of achieving suitable composition with ability of high amount of equilibrium swelling ratio and low amount of salt sensitivity factor (f). The results showed that high ratio of Cr(OAc) 3 /copolymer (>0.39) and high concentration of copolymer (>27 000 ppm) were suitable areas for conventional hydrogels because of minimum f factor with still low ability of gel swelling. However, the results of NC hydrogels with composition of copolymer concentrations of 23 750 to 30 000 ppm, Cr(OAc) 3 /copolymer ratio of 0.28 and nano Na-MMT concentrations of 500 to 800 ppm represented a significantly high amount of swelling and low amount of f factor. Coreflooding tests were applied to investigate the effect of polymer gel swelling in porous media for water shutoff treatment. The values of the residual resistance factor of water/oil for samples with high and low swelling ratio were 32.34 and 7.08, respectively, confirming the ability of the polymer gel with high swelling ratio in reducing the relative permeability of water/oil in porous media.

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