Voltammetric Studies of Propranolol and Hydrochlorothiazide Oxidation in Standard and Synthetic Biological Fluids Using a Nitrogen-Containing Tetrahedral Amorphous Carbon (ta-C:N) Electrode

• Nitrogen-containing tetrahedral amorphous carbon electrode for electroanalysis.
• Electrochemical behavior of propranolol (PROP) and hydrochlorothiazide (HTZ).
• ta-C:N electrode presents good electrochemical performance for PROP and HTZ.
• Electrochemical performance of ta-C:N electrode is similar to the BDD electrode.
• PROP and HTZ are simultaneously quantified in artificial biological samples.

The electrochemical detection of two pharmaceuticals, propranolol (PROP) and hydrochlorothiazide (HTZ), was studied using a nitrogen-containing tetrahedral amorphous carbon (ta-C:N) electrode. Measurements were also made using a boron-doped diamond (BDD) electrode, for comparison. The ta-C:N electrode functioned well for the simultaneous determination of PROP and HTZ in artificial urine and serum by square-wave voltammetry, both of which were detected at high positive potentials. The PROP (ca. 1.2 V) and HTZ (ca. 1.4 V) oxidation peak potentials were separated by about 200 mV. The respective analytical response curves presented good linearity in the investigated concentration range from 0.9 to 9.8 μmol L−1 for PROP and from 3.0 to 9.8 μmol L−1 for HTZ with calculated limits of detection (S/N = 3) of 0.75 μmol L−1 (∼194 ng/mL) for PROP and 2.50 μmol L−1 (∼744 ng/mL) for HTZ. Essentially, the lowest concentration measured voltammetrically was the LOD. The results indicate that the ta-C:N electrode could be an excellent new carbon material for electrochemically-active analytes requiring high potentials for detection.

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