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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