ABSTRACT
A validated simple, rapid, sensitive and specific square-wave voltammetric technique is described for the determination of acebutolol (AC) following its accumulation onto a hanging mercury drop electrode in a Britton-Robinson universal buffer of pH 7.5. The optimal procedural conditions were: accumulation potential Eacc = - 0.8 V versus Ag/AgCl/KCl, accumulation duration tacc = 30 s, pulse-amplitude = 70 mV, scan rate = 100 mV/s, frequency = 30 Hz, surface area of the working electrode = 0.6 mm2 and the convection rate = 2000 rpm. Under these optimized conditions, the adsorptive stripping voltammetry (AdSV) peak current was proportional over the concentration range 5 × 10-7 - 6 × 10-6 M (r = 0.999). Recoveries for acebutolol from human plasma and urine were in the range 97-103% and 96-104% respectively. The method proved to be precise (intra-day precision expressed as %RSD in human plasma ranged from 2.9 - 3.2% and inter-day precision expressed as %RSD ranged from 3.4 - 3.8%) and accurate (intra-day accuracies expressed as % error in human urine ranged from -3.3 - 2.8% and inter-day accuracies ranged from -3.3 - 1.7%). The limit of quantitation (LOQ) and limit of detection (LOD) for acebutolol were 1.7 × 10-7 and 5 × 10-7 M, respectively. Possible interferences by substances usually present in the pharmaceutical formulations were investigated with a mean recovery of 101.6 ± 0.64%. Results of the developed square-wave adsorptive stripping voltammetry (SW-AdSV) method were comparable with those obtained by reference analytical method.
ABSTRACT
Square-wave adsorptive stripping voltammetric (SW-AdSV) determinations of trace concentrations of the coloring agent fast green were described. The analytical methodology used was based on the adsorptive preconcentration of the dye on the hanging mercury drop electrode, and then a negative sweep was initiated. In pH 10 carbonate supporting electrolyte, fast green gave a well-defined and sensitive SW-AdSV peak at -1220 mV. The electroanalytical determination of this dye was found to be optimized in carbonate buffer (pH 10) with the following experimental conditions: accumulation time (120 s); accumulation potential (-0.8 V); scan rate (800 mV/s); pulse amplitude (90 mV); frequency (90 Hz); surface area of the working electrode (0.6 mm2); and the convection rate (2000 rpm). Under these optimized conditions, the AdSV peak current was proportional over the concentration range 2 x 10(-8) -6 x 10(-7) M (r = 0.999), with an LOD of 1.63 x 10(-10) M (0.132 ppb). This analytical approach possessed more enhanced sensitivity than conventional chromatography or spectrophotometry, and was simple and quick. The precision of the method in terms of RSD was 0.17%, whereas the accuracy was evaluated via the mean recovery of 99.6%. Possible interferences by several substances usually present as food additive azo dyes (E110, E102, E123, and E129), natural and artificial sweeteners, and antioxidants were also investigated. Applicability of the developed electroanalysis method was illustrated via the determination of fast green in ice cream and soft drink samples.
