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- Author or Editor: A. Khan x
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Summary
Titan yellow has been adsorbed on a strongly basic anion-exchange resin. The effects of concentration, pH, time, and temperature on adsorption of the dye by the resin have been studied. The effects of surfactants on the distribution coefficients of metal ions were also studied. On the basis of distribution coefficients several binary separations of analytical importance (Zn(II) from Hg(II), Zn(II) from Pb(II), Cu(II) from Pb(II), Cd(II) from Pb(II), and Cu(II) from Hg(II) have been achieved on a column containing the Titan yellow-modified resin. Hg(II) and Pb(II) were selectively analysed in synthetic mixtures.
Summary
We present the comprehensive chromatographic profiles of three scorpion species, Androctonus crassicauda, Androctonus bicolor, and Leiurus quinquestriatus, commonly inhabited to Middle East regions. Their venoms were milked by electrical stimulation, diluted with distilled water, properly mixed and centrifuged to separate the mucus from venom. The clear supernatant was filtered and the protein concentration was determined. Pre-diluted venoms were chromatographed on FPLC (fast protein liquid chromatography) and RP-HPLC (reversed-phase high-performance liquid chromatography) and the fractions were collected for molecular weight determination. Both techniques have resulted clearly distinguishable chromatographic patterns that can be used for identification of scorpion species and having a quick indication of venom toxicity.
A rapid, accurate, and sensitive reverse phase high-performance liquid chromatographic method was developed and validated for the simultaneous determination and quantification of glibenclamide and thymoquinone in rat plasma in the presence of internal standard (thymol). Chromatograms were developed with methanol, acetonitrile, and buffer (50:20:30, v/v/v) solvent system on a Symmetry® C18 (5 μm, 3.9 × 150 mm) column, and pH was adjusted to 4.5 with orthophosphoric acid. Mobile phase was pumped at a flow rate of 1.5 mL min−1 with 254 nm ultraviolet (UV) detection. Validation of the method was performed in order to demonstrate its selectivity, linearity, precision, accuracy, limits of detection, and quantification (LOD and LOQ). Standard curves were linear (r 2 = 0.996 and 0.999 for glibenclamide and thymoquinone) over the concentration range 0.5–50 μg mL−1. The coefficient of variation (CV) of < 6% and accurate recovery of 87.54–105.19% for glibenclamide and CV of <5% and accurate recovery of 86.08–103.19% for thymoquinone were found to be in the selected concentration range of 0.5–50 μg mL−1. The lower limits of detection and quantitation of the method were 0.109 and 0.332 μg mL−1 for glibenclamide and 0.119 and 0.361 μg mL−1 for thymoquinone, respectively. The within and between-day coefficients of variation were less than 7%. The validated method has been successfully applied to measure the plasma concentrations in a drug interaction study of glibenclamide with thymoquinone in an animal model to illustrate the scope and application of the method.
Continuous-flow synthesis of specific functional materials is now seen as a reliable synthesis approach that gives consistent product properties. This perspective article aims to survey recent work in some of the relevant areas and to identify new domains where flow synthesis of functional materials can be better than the conventional synthesis methods. It also emphasizes the need for developing high-throughput integrated synthesis and screening systems for almost all functional materials so that laboratory-scale recipes can be transformed into reliable manufacturing processes. New areas relevant to functional materials which have remained unexplored in flow synthesis are also highlighted.
Summary
Ashwaghanda, Withania somnifera, is one of the most widely used herbs in Ayurvedic medicine. Leaves and roots are the traditionally used parts of the plant. An RP-HPLC method using a binary acetonitrile-water gradient containing 0.1% acetic acid has been developed for analysis of withaferin A. The method was validated in accordance with ICH guidelines and used for analysis of the withanolide content of the flowers, leaves, and roots of W. somnifera. The withanolide content was highest in the flowers.
Summary
A stability-indicating reversed-phase high-performance liquid chromatographic method has been developed for analysis of gemifloxacin in tablet formulations. When the drug was subjected to forced degradation under acidic, basic, thermal, oxidative, and photolytic conditions, the degradation products produced were successfully separated on a 250 mm × 4.6 mm, 5-μm particle, C18 column with ammonium acetate buffer (pH 2.7; 0.05 m)-acetonitrile 70:30 (υ/υ) as mobile phase at a flow rate of 0.7 mL min−1. Diode-array detection was performed at 272 nm. The method was validated in accordance with ICH guidelines. Response was a linear function of concentration over the range 0.256–128 μg mL−1 (correlation coefficient 0.9990). The limits of detection and quantification were 10 and 30 ng mL−1, respectively. Separation of gemifloxacin from its stress-induced degradation products and excipients was adequate; resolution was >1.5 within 11 min. The purity index for the gemifloxacin peak after all types of stress was >0.999, indicating complete separation of the analyte peak from the degradation products. The method can therefore be regarded as stability-indicating. It is rapid, and suitable for purity and assay determination not only for routine quality control but also in stability studies.
Summary
In this paper we describe a sensitive and reproducible reversed-phase high-performance liquid chromatography (HPLC) method with photodiode-array detection for isolation and quantification of the bioactive hydrophilic constituent 7-(1-O-β-d-galacturonide-4′-(1-O-β-d-glucopyranosyl)-3′,4′,5,7-tetrahydroxyflavone, 1, from the seeds of Cuminum cyminum. Compound 1 was separated isocratically on a C18 preparative column, in high purity, after removal of solvents. The purity and identity of the compound were established by use of LC-mass spectrometry and by spectroscopic techniques (1H and 13C NMR). The purity of 1 was also confirmed by HPTLC.
