Voltammetric determination of natamycin using a cathodically pretreated boron-doped diamond electrode in the presence of sodium dodecyl sulfate

•The signal of natamycin was investigated at cathodically pretreated BDD electrode.•The use of SDS significantly increased the sensitivity of the measurements.•Sensitive SWV procedure for the natamycin determination was developed.•Possibility for drug quality control and natamycin analysis in food samples. The work describes a new electrochemical method of assaying natamycin in pharmaceutical preparations and food products. The proposed procedure involves the use of cathodic-conditioned boron-doped diamond electrode (BDD) and sensitive electrochemical techniques. Well-defined oxidation peaks of natamycin, but no reduction peaks, were obtained in cyclic voltammetry. The sensitivity of the obtained measurements was significantly improved when a surfactant, sodium dodecyl sulfate (SDS), was present in the supporting electrolyte solution. The method of square-wave voltammetry was used to determine the linear relationship between the current and natamycin concentration. The linear relationship was obtained in the concentration range from 9.75 × 10−8 to 1.16 × 10−6 mol·L−1. In optimum conditions, i.e., 0.05 mol·L−1 H2SO4 containing 5.07 × 10−4 mol·L−1 SDS at the potential of 0.81 V (vs. SCE), the limit of detection was 3.1 × 10−8 mol·L−1. The method has good precision, which is proved by low relative standard deviation (approx. 1%). The obtained values of recovery prove the accuracy of the proposed procedure. The developed procedure was successfully tested for the assay of natamycin in single-ingredient and multi-ingredient pharmaceutical preparations and in wine samples.