A thermostated electrochemical flow cell with a coupled bismuth film electrode for square-wave anodic stripping voltammetric determination of cadmium(II) and lead(II) in natural, wastewater and tap water samples

•An electrochemical system with a minimal handling of solutions and low toxicity.•An efficient thermostated control was performed for in loco measurements.•An automated system to perform on line and ex situ electrodeposition of bismuth.•The flow system was used to prepare analytical curves, standard addition, recovery.•Low waste generation and bismuth were in agreement with the green chemistry.

In order to reduce the sample consumption and waste generation for electrochemical purposes, a screen-printed electrode (SPE) used for electrodeposition of bismuth film (SPE-BiFE) and a thermostated electrochemical flow cell (EFC) were developed. The SPE-BiFE with the EFC was employed to determine Cd2+ and Pb2+ ions in natural, wastewater and tap water samples by square-wave anodic stripping voltammetry (SWASV). For this, the flow-batch analysis (FBA) approach based on solenoid micro-pumps and three-way valves was developed to carry out a fully automated procedure with temperature control. Furthermore, the FBA and the SWASV parameters were optimized, on line simultaneous determination of Cd2+ and Pb2+ ions was performed and two analytical curves were linearly acquired in the concentration ranges from 6.30 to 75.6 µg L−1 and from 3.20 to 38.4 µg L−1, respectively. Moreover, limits of detection of 0.60 µg L−1 and 0.10 µg L−1 for Cd2+ and Pb2+, respectively, were obtained. Studies of precision for the same SPE-BiFE and repeatability for five built SPE-BiFE were carried out for Cd2+ and Pb2+ ion measurements and RSD of 4.1% and 2.9% (n=3) with repeatabilities (n=5) of 6.5% and 8.0% were respectively obtained for both analytes. Besides, a low consumption of 700 µL of reagents and a sampling frequency of 13 h−1 were acquired. Simplicity, fast response, accuracy, high portability, robustness and suitability for in loco analyses are the main features of the proposed electroanalytical method.

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