A Novel Sensitive Method for the Determination of Cadmium and Lead Based on Magneto‐Voltammetry

Abstract

A novel method for the ultratrace determination of Cd 2þ and Pb 2þ based on magneto-voltammetry was developed. In the presence of a low strength magnetic field of 0.6 T, square wave stripping voltammetry (SWSV) of Cd 2þ and Pb 2þ was performed in this determination. A high concentration of redox species Fe 3þ was added to the analytes to generate a large cathodic current during the preconcentration step. A large Lorentz force arising from the flux of net current through the magnetic field resulted in convective solution flow due to magnetohydrodynamics. Then more metal ions deposited on the electrode surface at a faster rate and an enhancement as large as 160% for the stripping peak current was observed. Under the optimal conditions, this method exhibits high sensitivities of 5.67 mA mM 21 for Cd 2þ and 6.98 mA mM 21 for Pb 2þ , over the 1 Â 10 28 -1 Â 10 26 mol l 21 range. Detection limits as low as 9.0 Â 10 210 and 8.6 Â 10 210 mol l 21 for Cd 2þ and Pb 2þ were obtained with a 2 min preconcentration time, respectively. The method was successfully applied to detect Cd 2þ and Pb 2þ in real water samples and the results were in agreement with atomic absorption spectrometry.

Magneto-hydrodynamics based microfluidics

“…The application of MHD to weakly conductive electrolyte solutions is somewhat more complicated due to electrodes' electrochemistry. Recently, various MHD-based microfluidic devices including micro-pumps (Jang and Lee, 2000; Lemoff and Lee, 2000; Huang et al, 2000; Bau, 2001; Zhong et al, 2002; Bau et al, 2002, 2003; Sawaya et al, 2002; West et al, 2002, 2003; Ghaddar and Sawaya, 2003; Bao and Harrison, 2003a, 2003b; Eijkel et al, 2004; Wang et al, 2004; Arumugam et al, 2004, 2006; Qian and Bau, 2005b; Homsy et al, 2005, 2007; Affanni and Chiorboli, 2006; Aguilar et al, 2006; Kabbani et al, 2007; Patel and Kassegne, 2007; Duwairi and Abdullah, 2007; Ho, 2007), stirrers (Bau et al, 2001; Yi et al, 2002; Qian et al, 2002; Gleeson and West, 2002; Xiang and Bau, 2003; Gleeson et al, 2004; Qian and Bau, 2005a), networks (Bau et al, 2002, 2003), heat exchangers (Sviridov et al, 2003; Singhal et al, 2004; Duwairi and Abdullah, 2007), and analytical and biomedical devices (Leventis and Gao, 2001; West et al, 2002, 2003; Bao and Harrison, 2003a; Lemoff and Lee, 2003; Eijkel et al, 2004; Clark and Fritsch, 2004; Homsy et al, 2007; Gao et al, 2007; Panta et al, 2008) operating under either DC or AC electric fields have been designed, modeled, constructed, and tested. The DC operation is often adversely impacted by the electrodes' electrochemistry leading to bubble formation and electrode corrosion.…”