http://nopr.niscpr.res.in/handle/123456789/19939 2026-10-09T23:19:53Z http://nopr.niscpr.res.in/handle/123456789/20020 Title: Solubility enhancement of rofecoxib in water in the presence of hydrobhilic polymers, surfactants, co-solvents, and small molecules at310.15K† Authors: Desai, K H; Kulkarni, A R; Agnihotri, S A; Gudasi, K B; Aminabhavi, T M Abstract: Solubility enhancement of rofecoxib in water has been studied in presence of different conce ntrations of hydrophilic polymers like polyethylene glycol-4000 polyethylene glycol-6000 and polyvinylpyrrolidone (PVP- K30); surfactants like Span-20, Tween-80 and sodium lauryl sulfate (SLS): co-solvents like ethanol, propylene glycol and glycerol and small molecules like urea, mannitol and <i>β</i>-cyclodextrin at 310.15<i> </i>K. Drug analysis has been carried out by HPLC method using UV detector at 254 nm. Drug solubility is greatly enhanced in the presence of PVP-K30, SLS, and ethanol. In the presence of small molecules, urea enhances the solubility much higher than mannitol or <i>β</i>-cyclodextrin. Page(s): 1667-1669 2006-07-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/20019 Title: TLC separation of L-tryptophan using microemulsion mobile phase and its spectrophotometric determination Authors: Mohammad, Ali; Hena, Sufia; Bhawani, Showkat Ahmad Abstract: The TLC system comprising silica gel as the stationary phase, and water- in –oil microemul sion (SDS+water+heptane+n-pentanol; (160 g + 8 mL + 16 mL + 25 mL) as the mobile phase, has been identified as the most favourable system for selective separation of L-tryptophan from other amino acids in the presence of metal cation impurities. The proposed method is applicable to the identification and separation of L-tryptophan from drug samples such as Astymin -m (Forte), Astymin (liquid) and Alamin (Forte). The separation up to 10μg of L-tryptophan from milligram quantities (up to 0.77 mg) of other amino acids has also been realized. The quantitative estimation of L-tryptophan by spectrophotometry (λ_max 570 nm) after separation from other amino acids has been done. The recovery of tryptophan is around 98% and its limit of detection on silica gel layer is 0.13 μg. Page(s): 1663-1666 2006-07-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/20018 Title: Spectrophotometric determination of copper(II) in alloys and edible oils using 2-acetylthiophene thiosemicarbazone Authors: Rao, M Sayaji; Prasad, N B L; Reddy, K Hussain Abstract: The reagent, 2-acetylthiophene thiosemicarbazone (ATT) has been synthesized and characterized based on spectral data, The reagent gives intense yellowish green coloured complex (λ_max=370 nm) with copper(II) in sodium acetate-acetic acid buffer (<i>p</i>H 5-7) medium. The colour reaction has been investigated in detail. The molar absorptivity and Sandell's sensitivity of the copper(II) complex of ATT are 1.83 × 10⁴ L. mol^-1 cm^-1 and 0.0034 μg of Cu(II) cm^-2 respectively. The method has been used for the determination of copper(II) in alloys, edible oils and seeds. Page(s): 1659-1662 2006-07-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/20017 Title: 6-Chloro-3-hydrox y-2- [2 '-(5 '-methylfuryl)]-4<i>H</i>-chromen-4-one as an analytical reagent for the spectrophotometric determination of tungsten(VI) Authors: Agnihotri, R; Agnihotri, N; Mehta, J R Abstract: A 1:2 light yellow complex of tungsten (VI) is formed with 6-chloro-3-hydroxy-2 –[2'-(5'-methylfuryl)]<i>-</i>4<i>H </i>-chromen-4-one (CHMFC) in 0.18-0.32 <i>M </i>HClO₄ medium. The complex is extractable into chloroform and absorbs maximally at 4:15 nm. The absorbance remains constant for more than 1 h with molar absorptivity, detection limit and Sandell’s sensitivity as 2.16×10⁴ L mol^-1 cm^-1, 0.131μg mL^-1 and 0.0085 μg W cm^-2, respectively. Beer's law is obeyed in the concentration range of 0-2.6 μg W mL^-1 the correlation coefficient is, <i>r</i>=1.001, Oxalate interferes in the tungsten determination. The method has been satisfactorily applied to the analysis of tungsten in various synthetic and technical samples. Page(s): 1655-1658 2006-07-01T00:00:00Z