Determination of Atorvastatin with Voltammetric Sensors Based on Nanomaterials

This paper presents an accurate and fast electrochemical method for atorvastatin determination in pharmaceutical products. Two screen-printed sensors, one—carbon based (SPCE) and one based on carbon nanotubes and gold nanoparticles (AuNP-CNT/SPCE) were used during the electrochemical analyses. At all experimental stages, cyclic voltammetry was employed, both for the characterization of the sensors and their electrochemical behavior, and for quantitative determinations. AuNP-CNT/SPCE has showed an extended active area, higher intensity peaks, better reversibility and lower background current than the unmodified sensor. For atorvastatin quantification, a calibration curve has been developed within the 1.2–606.25 µM concentration range. A linearity relation between the current of the anodic peak and concentration has been obtained in the range 1.2–53.33 µMfor both sensors. With the AuNP-CNT/SPCE sensor, low values of limit of detection, LOD (1.92 × 10−7 M) and limit of quantification, LOQ (6.39 × 10−7 M) have been obtained, which demonstrates the feasibility of the method of determining atorvastatin from real samples. Atorvastatin amount has been successfully determined from pharmaceutical products using AuNP-CNT/SPCE. The results were similar to the manufacturer’s specifications regarding the dosage per tablet and to the concentrations obtained by applying the FTIR spectrometric method.

Simultaneous voltammetric detection of cadmium(II), arsenic(III), and selenium(IV) using gold nanostar-modified screen-printed carbon electrodes and modified Britton-Robinson buffer

The present work reports a newly developed square wave anodic stripping voltammetry (SWASV) methodology using novel gold nanostar-modified screen-printed carbon electrodes (AuNS/SPCE) and modified Britton-Robinson buffer (mBRB) for simultaneous detection of trace cadmium(II), arsenic(III), and selenium(IV). During individual and simultaneous detection, Cd²⁺, As³⁺, and Se⁴⁺ exhibited well-separated SWASV peaks at approximately - 0.48, - 0.09, and 0.65 V, respectively (versus Ag/AgCl reference electrode), which enabled a highly selective detection of the three analytes. Electrochemical impedance spectrum tests showed a significant decrease in charge transfer resistance with the AuNS/SPCE (0.8 kΩ) compared with bare SPCE (2.4 kΩ). Cyclic voltammetry experiments showed a significant increase in electroactive surface area with electrode modification. The low charge transfer resistance and high electroactive surface area contributed to the high sensitivity for Cd²⁺ (0.0767 μA (0.225 μg L^-1)^-1), As³⁺ (0.2213 μA (μg L^-1)^-1), and Se⁴⁺ (μA (μg L^-1)^-1). The three analytes had linear stripping responses over the concentration range of 0 to 100 μg L^-1, with the obtained LoD for Cd²⁺, As³⁺, and Se⁴⁺ of 1.6, 0.8, and 1.6 μg L^-1, respectively. In comparison with individual detection, the simultaneous detection of As³⁺ and Se⁴⁺ showed peak height reductions of 40.8% and 42.7%, respectively. This result was associated with the possible formation of electrochemically inactive arsenic triselenide (As₂Se₃) during the preconcentration step. Surface water analysis resulted in average percent recoveries of 109% for Cd²⁺, 93% for As³⁺, and 92% for Se⁴⁺, indicating the proposed method is accurate and reliable for the simultaneous detection of Cd²⁺, As³⁺, and Se⁴⁺ in real water samples. Graphical abstract.