Stripping voltammetric determination of valsartan in bulk and pharmaceutical products.

Stripping voltammetric determination of valsartan using a hanging mercury drop electrode (HMDE) was described. The method was based on adsorptive accumulation of the species at HMDE, followed by first harmonic alternating current AC stripping sweep at pH 6. The behavior of adsorptive stripping response was thoroughly studied under various experimental conditions, e.g. type of supporting electrolyte, pH, accumulation time, scan rate and mode of sweep. In Britton-Robinson buffer solution, a quasi-reversible reduction process involving transfer two electrons and two protons was took place. The response was linear over the concentration range of 0.08-0.64 microg/ml with regression coefficient 0.999 and limit of detection 0.02 microg/ml. The average of determinations of the cited compound in oral dosages with its standard deviation was 101.11 +/- 4.38%. The result obtained by the proposed method was compared with that obtained by the UV-spectrophotometric technique. Furthermore, the proposed method was successfully applied as stability-indicating method for determining valsartan in the presence of its acid induced degradation products.

Adsorptive stripping voltammetric determination of triprolidine hydrochloride in pharmaceutical tablets.

The electrochemical behavior of antihistaminic drug, viz. triprolidine hydrochloride (TripCl), at a hanging mercury drop electrode (HMDE) is investigated. Chemical and electrical parameters affecting the adsorptive voltammetric measurements are optimized. Different modes of sweep, viz. direct current DC, normal pulse NP, differential pulse DP and square wave SW modes, over the potential range from -800 to -1400 mV, are used in the presence of 0.04 M Britton-Robinson buffer pH 11, with accumulation time 30 s, scan rate 50 mV/s and pulse amplitude 50 mV. The reduction process is irreversible and involved the transfer of two electrons and two protons. Their responses are linear over the concentration range 15-157 ng/ml with average correlation coefficient 0.9998, while the detection limit is 2.64, 6.24, 8.80 and 2.12 ng/ml for DC, DP, SW and NP mode, respectively. The differential pulse method has been applied successfully for the determination of the drug in Egyptian pharmaceutical preparation with mean recovery 99.55+/-0.67%.

Adsorptive stripping voltammetric determination of ambroxol.

An electrochemical procedure for the determination of ambroxol in mucolytics was described. The method was based on adsorptive accumulation of the species at the hanging mercury drop electrode (HMDE), followed by one of different modes of stripping sweep, viz. direct current tast (DCT), differential pulse (DP), square wave (SW) and first harmonic alternating current (AC1). The behaviour of adsorptive stripping response was studied under various experimental conditions, e.g. type of supporting electrolyte, pH, accumulation time, pulse amplitude, scan rate and mode of sweep. In Britton-Robinson buffer solution, an irreversible reduction process involving transfer of one electron and one proton was took place. The response was linear over the 0.2-6 microg/ml concentration range. Determination of the compound in oral dosage forms was achieved using the standard addition method. The average of determinations obtained by the squarewave adsorptive voltammetric method with its relative standard deviation was 99.8 +/- 2.40%.

Simultaneous spectrophotometric determination of salbutamol and bromhexine in tablets.

Typical anti-mucolytic drugs called salbutamol hydrochloride and bromhexine sulfate encountered in tablets were determined simultaneously either by using linear regression at zero-crossing wavelengths of the first derivation of UV-spectra or by application of multiple linear partial least squares regression method. The results obtained by the two proposed mathematical methods were compared with those obtained by the HPLC technique.

Near infra-red reflectance spectroscopic determination of metformin in tablets.

A rapid and simple near infra red reflectance spectroscopic method was described for determination of anti-diabetic tablets. Partial least squares method was applied to the Savitsky-Golay smoothed first derivative spectral data revealed over wavelength range 1000-2500 nm from 11 different pulverized tablet batches in 2-mm quartz cell. The results were agreed well with those obtained by the official British Pharmacopoiea 1998 UV assay of metformin.