ascorbic-acid and tetrabutylammonium

A simple and relatively green method has been developed for the determination of chromium based on the extraction of chromium (VI) as its ion-association complex with tetrabutylammoniumiodide (TBAI) in acidic medium. The ion-pair is extracted using isobutylmethylketone (MIBK) as the solvent. The concentration of the extracted chromium (VI) in the organic layer was measured spectrophotometrically at a wavelength maximum of 366 nm and the organic layer was characterized using FT-IR spectroscopy. The influence of various analytical parameters such as pH, aqueous phase volume, equilibration time, interfering ions etc. has been studied in detail. The extracted chromium (VI) was back extracted into the aqueous phase to the non-toxic chromium (III) using ascorbic acid. The calibration graph was linear in the range of 0-2 microg mL(-1) chromium (VI) with a relative standard deviation of 2.4%. A detection limit of 0.25 microg in 25 mL aqueous phase volume could be achieved and the validity of the proposed method has been checked by applying it to synthetic mixtures, spiked water sample, electroplating wastewater and certified reference material BCR-715.

Topics: Ascorbic Acid; Calibration; Chromium Compounds; Electroplating; Hydrogen-Ion Concentration; Indicators and Reagents; Industrial Waste; Quaternary Ammonium Compounds; Reproducibility of Results; Solvents; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Sulfuric Acids; Waste Disposal, Fluid; Water Pollutants, Chemical

The five active drug substances and two of the excipients present in Frenadol, a cold medication, were separated. The active drug components dextromethorphan HBr monohydrate, ascorbic acid, caffeine, paracetamol and chlorpheniramine maleate were quantitatively assayed by a mixed ion pair LC method. The excipients separated were citric acid and maleic acid. The HPLC assay included dual-wavelength detection to simultaneously quantify the large concentration of paracetamol and the much lower concentration of chlorpheniramine and dextromethorphan. Both tetrabutylammonium hydrogen sulphate (TBA) and pentane sulphonic acid (PSA) were necessary for resolution of the seven compounds. The TBA was necessary to lessen peak tailing for dextromethorphan and chlorpheniramine, to retain ascorbic acid and to shorten assay time. The pentane sulphonic acid enhanced peak shape for dextromethorphan and chlorpheniramine. The assay of the active drug substances was validated for use in quality control applications. Validation studies demonstrated that the procedure was accurate, linear, precise, reproducible and rugged. The method conformed to both USP and EC validation guidelines.

Topics: Acetaminophen; Alkanesulfonic Acids; Ascorbic Acid; Caffeine; Chlorpheniramine; Chromatography, High Pressure Liquid; Dextromethorphan; Dosage Forms; Nonprescription Drugs; Quality Control; Quaternary Ammonium Compounds; Reference Standards; Reproducibility of Results