Voltammetric assay of Guaifenesin in pharmaceutical formulation.

The electrochemical oxidation of Guaifenesin in a pharmaceutical formulation containing Guaifenesin has been carried out in Britton-Robinson buffer (BRB) (0.04 mol L-1) on platinum electrode. Guaifenesin exhibits a well-defined irreversible oxidation peak at 0.924 V/ref. The influence of pH on the oxidation of Guaifenesin was studied in BRB (pH range 2-5). A method for the analysis of Guaifenesin in BRB (0.04 mol L-1, pH 2), which allows quantification over the range 20-60 microg mL-1, was proposed and successfully applied to the determination of Guaifenesin in syrup with mean recovery and relative standard deviation of 103.3% and 1.32%, respectively.

Determination of cisapride, its oxidation product, propyl and butyl parabens in pharmaceutical dosage form by reversed-phase liquid chromatography.

A simple, rapid and reproducible high-performance liquid chromatography (HPLC) assay for cisapride, its oxidation product (OP), propyl and butyl parabens in a pharmaceutical formulation is described. Chromatography was performed at room temperature by pumping acetonitrile-20 mM phosphate buffer pH 7 (50:50, v/v) at 1.5 ml min(-1) through C8 reversed-phase column. Cisapride, OP, propyl and butyl parabens were detected at 276 nm and were eluted at 9.7, 3.1, 5.1 and 7.1 min, respectively. Calibration plots were linear (r>0.999) for all compounds from 0.5 to 200 microg ml(-1) for cisapride and OP and 0.1-200 microg ml(-1) for propyl and butyl parabens. Detection limits for cisapride, OP, propyl and butyl parabens were 40, 46, 48 and 54 ng ml(-1), respectively. Forced degradation investigations showed that cisapride does not undergo degradation under heat, acidic and basic conditions but it was susceptible to oxidation. The proposed method was successfully applied to the assay of cisapride in the presence of preservatives and OP in a commercial suspension.

Differential-pulse polarography (DPP) determination of betamethasone valerate in dosage form.

The electrochemical reduction of betamethasone valerate (BV) in a pharmaceutical formulation containing neomycin has been carried out in Britton-Robinson buffer (BRB) (0.04 mol L(-1)) by differential-pulse polarography (DPP). BV exhibits a well-defined irreversible reduction peak at -1.03 V/ref. The influence of pH on the reduction of BV was studied in Britton-Robinson buffer (pH range 1.7-10). A method for the analysis of BV in BRB (0.04 mol L(-1)), which allows quantification over the range 3.9x10(-6)-1.1x10(-4) mol L(-1), was proposed and successfully applied to the determination of BV in tablets with mean recovery and relative standard deviation of 100.81% and 0.45%, respectively.

Release of heavy metals from Tunisian traditional earthenware.

Lead and other heavy metals are found to leach from the glazes of some Tunisian glazed earthenware in concentrations high enough to constitute a serious health hazard. When yellow/green and white/green colored mugs available on the Tunisian market were filled with acetic acid solutions, concentrations of up to 51 microg lead per ml of leachate were measured. The values greatly exceed the limit allowed by the US Food and Drug Administration (FDA) regulations for a 24-h leaching test. The use of a traditional milk derivative (leben) widely consumed as a beverage in Tunisia as a leaching agent shows that amounts as high as 1407 microg of lead is ingested per mug of milk derivative consumed. The use of such utensils may constitute a serious health hazard to the Tunisian consumer. Stringent regulations and controls are therefore required to protect the consumer against lead and other heavy metals of non-occupational origin.

Differential-pulse polarography determination of pipamperone in pharmaceutical formulations.

The electrochemical reduction of pipamperone has been carried out in aqueous solution in KNO(3) (0.1 mol l(-1)) by differential-pulse polarography (DPP). Pipamperone exhibits a well-defined irreversible reduction peak at -1.3 V/ref. The influence of pH on the reduction of pipamperone was studied in Britton-Robinson buffer (pH range 2-10). A method for the analysis of pipamperone in KNO(3) (0.1 mol l(-1)), which allows quantification over the range 1.6x10(-5)-2.0x10(-4) mol l(-1), was proposed and successfully applied to the determination of pipamperone in tablets with mean recovery and relative standard deviation (R.S.D.) of 100.35 and 0.49%, respectively.