Rex A Palmer, John Spencer, Andrew P Mendham, Babur Z Chowdhry, David R Lisgarten, Barry M Trost, Nico Cramer, Louise Male, Simon J Coles
3-(Propan-2-ylidene)benzofuran-2(3 H )-one, C 11 H 10 O 2 , crystallizes in the monoclinic space group P2 1 /c with unit cell parametersa =7.1869(3), b = 18.0636(10), c = 13.1656(7) b= 96.763(3), V =1697.28(15) , Z = 8 (Z? = 2 independent molecules, A and B, per asymmetric unit), D c  = 1.363 g cm -3  and the linear absorption coefficient = 0.093 mm -1 . The crystal structure determination was carried out using MoKa X-ray data measured at 120(2) K. In the final refinement cycle the data/restraints/parameter ratios were 3827/0/239, the goodness-of-fit on F2 = 1.019. Final R indices for [I>2sigma(I)] were R1 = 0.0517, wR2 = 0.1115 and R indices (all data) R1 = 0.1007, wR2 = 0.1354. The largest electron density difference peak and hole were 0.254 and -0.244 electrons sup>-3, respectively. The two independent molecules A and B have essentially identical bond lengths and angles and are highly planar, with rms deviation for all 12 non-H atoms of 0.0292 for molecule A and 0.0592 for molecule B. The two molecules in the asymmetric unit are assembled parallel to each other within 1.58(4) with each of the six atoms of benzene ring A overlapping with one of the atoms in benzene ring B at a mean distance of 3.84(3) . The closest contacts between molecules A and B are C(12A)H---O(4B) = 3.521 and C(11B)H---O(4A) = 3.441 The crystal structure is formed by infinite sheets of these assemblies all lying parallel to the (1 0`1) plane. The presence of two independent molecules in the asymmetric unit provides an opportunity to examine the molecular geometry in detail by comparison. The benzene ring in both molecules A and B exhibits distortions as a result of the presence of the furan moiety. In particular, C(1)-C(6) = 1.369(2) in molecule A and 1.367(2) in molecule B are both significantly less than the average of the other 10 C-C bonds, 1.393(2), by about 12?. Other examples of crystal structures are discussed where this effect is observed.
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Ananda Thangadurai Subramaniam, Jambulingam Munusamy, Saravanakumar Sengodan, Kamalakannan Danapal, Haritha D Siva Ganga Lakshmi, Varatha S Kunan
A simple, robust, precise and accurate reverse phase liquid chromatographic method was developed for simultaneous estimation of Atazanavir sulphate and Ritonavir in combined tablet dosage form by RP-HPLC method. Chromatography was carried out on a Nucleodur C 18Â column (150 mm x 4.6 mm x 5 m) using Acetonitrile: Methanol: Phosphate buffer, pH was adjusted to 3.0 with orthophosphoric acid in the ratio of 44:11:45 (V/V) as a mobile phase at a flow rate of 1.5 mL min -1 Â and eluents were monitored at 210 nm. The calibration curves were linear over the range of 34 102 ?g mL -1 Â for Atazanavir sulphate and 10 30 ?g mL -1 Â for Ritonavir. The average retention time of Atazanavir sulphate and Ritonavir was found to be 3.133 min and 6.133 min respectively. The method was reproducible, with good resolution of Atazanavir sulphate and Ritonavir. The results of the analysis have been validated statistically.
50-54
Ramesh Jayaprakash, Senthilkumar Natesan, Vijay Amirtharaj Ramasamy, Rajasekhar Kommi, Kiran R Gandhi
A simple, accurate, precise, economical and reproducible UV-Visible Spectrophotometric method has been developed for the simultaneous estimation of Lamivudine, Nevirapine and Zidovudine in bulk and in combined tablet dosage form. The stock solutions were prepared in methanol followed by the further required dilutions with distilled water. This method involves the formation and solving of simultaneous equations at 271, 282 and 267 nm, as absorbance maxima of lamivudine, nevirapine and zidovudine, respectively. Beers law obeyed the concentration range of 1.5-9, 2.5-15 and 3-18 g/mL for Lamivudine, Nevirapine and Zidovudine, respectively. The results of analysis were validated statistically and by recovery studies. The %RSD for the recovery study was less than 2. The proposed method can be effectively applied for the simultaneous estimation of these drugs in bulk and in combined tablet dosage form.
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