Simultaneous electrochemical sensing of Cd²⁺ and Pb²⁺ using screen-printed ionic liquid/graphene electrodes

ABSTRACT

In this work, a screen-printed ionic liquid-graphene electrode (SPIL-GrE) was fabricated and characterised for electrochemical detections of cadmium (Cd²⁺) and lead (Pb²⁺) using square wave voltammetry (SWV). Characterizations by scanning electron microscopy and Raman spectroscopy verified the presence of multilayer graphene sheets mixed with carbon nanoparticles. From SWV measurements under an optimal condition, the anodic currents for Cd²⁺ and Pb²⁺ of SPIL-GrE were 4.2 times and 1.4 times as high as those of a conventional screen-printed carbon electrode. In addition, the SWV currents of SPIL-GrE for Cd²⁺ and Pb²⁺ dissolved in 0.1 M HCl electrolyte solution (pH 1.0) were linear in the range of 250–2,500 ppb. The detection limits (3S/N) for Cd²⁺ and Pb²⁺ of SPIL-GrE were as low as 150 and 93 ppb (1.3 and 0.5 µM), respectively. Besides, the Cd²⁺ and Pb²⁺ peak currents of SPIL-GrE were negligibly interfered by the additions of Na⁺, K⁺, Mg²⁺, Ca²⁺, Co²⁺, Mn²⁺, Ni²⁺ and Fe³⁺ ions at the concentration 10 times as high as that of Cd²⁺ and Pb²⁺. Moreover, a single SPIL-GrE displayed good repeatability with the relative standard deviation (RSD, n = 10) of 8.7% and 4.1% for SWV peak currents towards 1,000 ppb (8.9 µM) Cd²⁺ and 1,000 ppb Pb²⁺ (4.8 µM), respectively. Furthermore, SPIL-GrEs produced in the same batch exhibited good reproducibility with RSD (n = 7) of 8.9% and 5.5% for 1,000 ppb Cd²⁺ and 1,000 ppb Pb²⁺, respectively. Lastly, the determination of Cd²⁺ and Pb²⁺ in fresh and sea water samples using the developed method statistically agreed well with the results of inductively coupled plasma atomic emission spectroscopy.

KEYWORDS:

• Screen-printed ionic liquid graphene electrode (SPIL-GrE)
• screen printing
• electrochemical detection
• graphene
• ionic liquid (IL)

Acknowledgement

The authors would like to thank the Graphene Sensor Laboratory (GPL), Graphene and Printed Electronics for Dual-Use Applications Research Division (GPERD), National Security and Dual-Use Technology Center (NSD), National Science and Technology Development Agency (NSTDA) for provision of research facilities.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research has received funding support from the NSRF via the Program Management Unit for Human Resources & Institutional Development, Research and Innovation [grant number B05F640091] and the National Research Council of Thailand [NRCT: N41A640181].