Multiparametric optimization of a new high-sensitive and disposable mercury (II) electrochemical sensor

An electrochemical sensor for mercury (II) determination was developed by modifying the surface of a commercial screen-printed carbon electrode (SPCE) with a polystyrene sulfonate-NiO-carbon nanopowder composite material. Mercury measurements were performed by differential pulse anodic stripping voltammetry (DPASV). Sensor composition and measurement conditions were optimized using a multivariate experiment design. A screening experiment by using a Plackett-Burman design was first performed in order to determine the main contributing factors to the electrochemical response. The most important factors were employed to establish the interactions between different experimental variables and get the best conditions for mercury determination. For this purpose, a five level central composite design and a response surface methodology were used. The optimized method using the developed NiO-PSS-SPCE sensor presents a very low limit of detection of 0.021 μg L(-1) and a linear response over two concentration ranges with two different slopes, from 0.05 to 2.0 μg L(-1) and between 2.0 and 75 μg L(-1). The sensor was successfully applied to mercury determination in water samples.