Simultaneous determination of three β-blockers at a carbon nanofiber paste electrode by capillary electrophoresis coupled with amperometric detection

In the paper, a novel carbon nanofiber paste electrode (CFPE) was fabricated and firstly used as a sensitive amperometric detector in capillary electrophoresis (CE) for the simultaneous determination of three β-blockers: sotalol, alprenolol and atenolol. Compared with the bare carbon paste electrode, the CFPE exhibited enhanced oxidation peak current responses to the analytes due to its excellent electrocatalytic activities, high conductivity and large effective surface area. Subsequently, effects of several important factors such as detection potential, pH and concentration of running buffer, separation voltage and injection time on the analysis were investigated. Under the optimum conditions, the three analytes could be separated and detected in a phosphate buffer (pH 8.5) within 11 min. The linear ranges were 0.1–100 μM for sotalol, 0.2–150 μM for alprenolol and 0.1–50 μM for atenolol and the detection limits were as low as 10−8 M magnitude (S/N=3). Moreover, the CFPE exhibited good repeatability and long-time stability. The proposed method was applied to determine the three β-blockers in spiked urine samples with satisfactory assay results. The good performance, low cost and straightforward preparation method of CFPE demonstrated that it could be used as a detector for CE–amperometric detection system for drug analysis.