Modified cell for stripping voltammetry using the static mercury drop electrode

Analysis of diflunisal by electrochemical methods

A new differential pulse polarographic (DPP) and differential pulse adsorptive stripping voltammetric (DPAdSV) methods for the electrochemical behavior and quantitative determination of diflunisal were described. In these voltammetric methods, the peak potential of diflunisal was found as -0.31 V (vs. Ag/AgCI) with selected Britton--Robinson buffer (BR, pH 7.8) as a supporting electrolyte. The variation of the peak current with the concentration of diflunisal were linear in the 9.0--40.0 and 4.0--30.0 microg ml(-1) concentration ranges for DPP and DPAdSV methods, respectively. The limits of detection (LOD) were found as 5.0 and 0.1 microg ml(-1) for DPP and DPAdSV methods, respectively. The developed methods were validated by evaluation of the validation parameters. The characteristics of the peak current of diflunisal were examined in detail and the results proved that the peak current has an adsorption characteristic. The developed methods were proposed for rapid determination of diflunisal in commercial tablets. The recovery studies showed that developed assays had a good accuracy and precision with mean recoveries 99.92 and 100.02% and mean variation coefficients 0.29 and 0.24% in DPP and DPAdSV methods, respectively.

Differential pulse adsorptive stripping voltammetric determination of ceftriaxone at a static mercury dropping electrode

Ceftriaxone is a member of the "third generation" of cephalosporin antibiotics which adsorbs strongly onto a mercury electrode. By using this phenomenon and by accumulating this compound at a static mercury dropping electrode prior to differential pulse voltammetric measurements, very high sensitivities can be readily achieved. The influence of several variables (including accumulation time, modulation amplitude, rest period, scan rate, and drop size) on the adsorptive stripping response has been evaluated. Peak currents were measured with a hanging mercury dropping electrode at -0.78 V versus an Ag/AgCl reference electrode in pH 3.0 Britton-Robinson buffer. The linear calibration range was 3.31 x 10(-11) to 2.17 x 10(-6) M.