Experimental design optimization of a simple and cost-effective voltammetric method for on-site determination of lead and cadmium in officinal plant leaves

This study introduces an improved method for the on-site quantification of cadmium and lead in officinal plants using differential pulse anodic stripping voltammetry (DP-ASV) with a glassy carbon electrode (GCE) modified by an in-situ mercury film (iMF-GCE). Initial experiments, conducted with one-variable-at-the-time (OVAT) approach, have provided suboptimal recovery rates and linearity, factors refined later through a systematic experimental approach involving two different designs: Plackett-Burman and Face Centered Composite Design (FCCD). Certified reference materials confirmed the method's reliability and its potential for effectiveness. The key parameters were optimized, achieving an Edep of -1.20 V and a tdep of 195 s for optimal performance. The results obtained allowed substantial improvements in accuracy, with recovery rates of 85.8% for Cd and 96.4% for Pb, and significantly lowered detection limits from, 1.54 μg L -1 to 0.63 μg L -1 for Cd and from 0.15 μg L -1 to 0.045 μg L -1 for Pb. Validation through field applications demonstrated the method's suitability for the analysis of official plants. Other applications are for environmental monitoring and food safety control. • The optimization improved Sensitivity and Accuracy of the method thakns to DOE application. • The setup is simple, requires minimal reagents, and can be deployed in the field. • Plant results obtained on-site showed good agreement with laboratory results. • This method could be used also for environmental monitoring and food analysis.