Direct determination of cadmium and lead in pharmaceutical ingredients using anodic stripping voltammetry in aqueous and DMSO/water solutions

• Direct Cd2+ and Pb2+ analysis/quantification in pharmaceutical ingredients.
• No acid digestion/dry ashing and an inexpensive alternative to ICP-based analyses.
• Electroanalysis on unmodified glassy C electrodes in aqueous and DMSO/H2O solutions.
• First heavy metal analysis in DMSO/water solutions by anodic stripping voltammetry.
• LODs in the μg L−1 (ppb) range in the presence of organic matrices.

A new electrochemical method has been developed to detect and quantify the elemental impurities, cadmium(II) (Cd2+) and lead(II) (Pb2+), either simultaneously or individually in pharmaceutical matrices. The electro-analytical approach, involving the use of anodic stripping voltammetry (ASV) on an unmodified glassy carbon electrode, was performed in both aqueous and in a 95/5 dimethyl sulfoxide (DMSO)/water solutions, without acid digestion or dry ashing to remove organic matrices. Limits of detection (LODs) in the μg L−1 [or parts per billion (ppb), mass/volume] range were obtained for both heavy metals - in the presence and absence of representative pharmaceutical components. To the best of our knowledge, the work demonstrates the first analysis of heavy metals in DMSO/water solutions through ASV. The strong reproducibility and stability of the sensing platform, as well as obviation of sample pretreatment show the promise of utilizing ASV as a sensitive, robust, and inexpensive alternative to inductively-coupled-plasma (ICP)-based approaches for the analysis of elemental impurities in, e.g., pharmaceutical-related matrices.

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