Development and Validation of a Novel Stability Indicating UPLC <Emphasis Type="SmallCaps">M</Emphasis>ethod for Analysis of Related Compounds and Assay of Bexarotene,an Anti-Cancer Agent

A novel liquid chromatographic method for the analysis of four potential impurities in the anti-cancer agent Bexarotene has been developed and validated using efficient chromatographic separation, achieved on a C₁₈ column (50 mm × 2.1 mm, 1.7-μm particles) with a simple isocratic mobile phase at a flow rate of 0.5 mL min^?1. The mobile phase consisted of a 70:30:0.1 (v/v/v) mixture of acetonitrile, water and trifluoroacetic acid, and quantification was achieved by use of ultraviolet detection at 260 nm. Resolution between Bexarotene and its four potential impurities was greater than 2.0. Regression analysis showed the r value (correlation coefficient) was >0.999 for Bexarotene and its four impurities. The method was capable of detecting all four impurities of Bexarotene at levels below 0.10 μg in a Bexarotene test concentration of 0.5 mg mL^?1 using an injection volume of 5 μL. The recovery for Bexarotene in assay method at a 100% level was observed to be 99.1 ± 0.32% with % RSD value of 0.5% for drug substance and 98.9 ± 0.46% for Bexarotene capsules with % RSD value of 0.4%. Recovery of imp-1, imp-2, imp-3, and imp-4 from bulk drug samples ranged from 96.3 to 102.0%. Recovery of imp-1, imp-2, imp-3, and imp-4 from Bexarotene Capsule samples ranged from 97.2 to 101.4%. A solution of Bexarotene in ethanol was stable for 48 h. The drug was also subjected to stress conditions as prescribed by ICH Guidelines. Degradation was found to occur under acidic and basic hydrolysis stress conditions; however, the drug was stable to oxidative, photolytic, and thermal stress. Assay of the stressed samples was calculated relative to a qualified reference standard and the mass balance was found to be close to 99.8%. The method was validated for linearity, accuracy, precision, and robustness.     

In vivo Confocal Raman Spectroscopic Analysis of the Effects of Infrared Radiation in the Human Skin Dermis

Human skin is the outer covering of the body, and its composition changes with overexposure to environmental pollution and solar radiation. Infrared (IR) radiation is capable of penetrating more deeply into the skin producing free radicals causing irreversible damage. Confocal Raman spectroscopy was considered as a potential tool for the in vivo analysis of the different metabolic conditions with respect to different depths of the skin. In this regard, this work verifies the influence of infrared radiation on the skin dermis after having been exposed to 432 J cm^?2 which corresponds to the dose received in a day in the summer time in a tropical region. This study was performed with 17 female volunteers who were divided into two groups. The marked skin area was exposed twice to IR radiation for a duration of 30 min each with an interval of 30 min. The spectral signatures were collected in the fingerprint region before (T0) and after 60 min (T60) of IR irradiation. The analysis shows that, on average, no significant variations occurred in group I and decreased collagen was observed in group II. However, when considering the effect seen in each individual, collagen degradation was detected in 60% of volunteers.     

Quality by Design enabled enhanced bioanalytical extraction and UFLC determination of vilazodone from rat serum

An ultrafast liquid chromatographic bioanalytical method was developed and validated for the determination of vilazodone in Wistar rat serum. Principles of quality by design were implemented for enhancing the bioanalytical liquid–liquid extraction of vilazodone from rat serum. A Box–Behnken design was utilized in the studies by selecting extraction time, centrifugation speed, and vortex time as the critical method variables for evaluating their effect on the analytical attribute, i.e., %recovery of vilazodone. Chromatographic separation was achieved within a run time of 10?min using a C-18 column and mobile phase comprising of methanol:phosphate buffer of pH 7 (85:15 v/v) flowing at 1.5?mL/min. Photodiode array detection was performed at 242?nm. Results of validation studies were satisfactory. The method was linear over a concentration of 100–2,000?ng/mL with acceptable accuracy and precision. Limits of detection and quantitation for the developed method were 50 and 100?ng/mL, respectively. This QbD-based approach was found suitable for routine bioanalysis of vilazodone in the biological matrix.     

Development of Protein Capped Nano Gold for NIR Photothermal and Molecular Imaging Applications for Diagnosis of Cancer Cells: In Vitro Studies

Journal of Cluster Science - The current work demonstrated an in vitro model of diastase capped gold nanoparticles (Au NPs) and nanoplates (Au NPts) as unique contrast agents for molecular imaging...     

A portable ultrahigh‐vacuum system for advanced synchrotron radiation studies of thin films and nanostructures: EuSi2 nano‐islands

A portable ultrahigh‐vacuum system optimized for in situ variable‐temperature X‐ray scattering and spectroscopy experiments at synchrotron radiation beamlines was constructed and brought into operation at the synchrotron radiation facility ANKA of the Karlsruhe Institute of Technology, Germany. Here the main features of the new instrument are described and its capabilities demonstrated. The surface morphology, structure and stoichiometry of EuSi₂ nano‐islands are determined by in situ grazing‐incidence small‐angle X‐ray scattering and X‐ray absorption spectroscopy. A size reduction of about a factor of two of the nano‐islands due to silicide decomposition and Eu desorption is observed after sample annealing at 1270 K for 30 min.     

Application of HR‐MAS NMR in the solid‐phase synthesis of a glycopeptide using Sieber amide resin

The solid‐phase synthesis (SPS) of a structurally complex glycopeptide, using Sieber amide resin, was monitored by high resolution magic angle spinning NMR, demonstrating the further application of this technique. A synthetic peptidoglycan derivative, a precursor of a biologically active PGN, known to be involved in the cellular recognition, was prepared by SPS. The synthesis involved the preparation of an N‐alloc glucosamine moiety and the synthesis of a simple amino acid sequence L ‐Ala‐D ‐Glu‐L ‐Lys‐D ‐Ala‐D ‐Ala. Last step consisted the coupling, on solid‐phase, of the protected muramyl unit to the peptide chain. Proton spectra with good suppression of the polystyrene signals in swollen resin samples were obtained in DMF‐d₇ as a solvent and by using a nonselective 1D TOCSY/DIPSI‐2 scheme, thus allowing to follow the SPS without losses of compound and cleavage from the resin. The assignment of the proton spectra of the resin‐bound amino acid sequence and of the bound glycopeptide was achieved through the combination of MAS COSY, TOCSY and NOESY. Copyright © 2010 John Wiley & Sons, Ltd.