Chloroplatinum(II) complex-modified MWCNTs paste electrode for electrochemical determination of mercury in skin lightening cosmetics Illyas Md Isa a,b, *, Mohamad Idris Saidin a , Mustaffa Ahmad a , Norhayati Hashim a,b , Suriani Abu Bakar b , Noorshida Mohd Ali a , Suyanta M.Si c a Department of Chemistry, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, 35900 Tanjong Malim, Perak, Malaysia b Nanotechnology Research Centre, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, 35900 Tanjong Malim, Perak, Malaysia c Department of Chemistry Education, Faculty of Mathematics and Natural Science, Yogyakarta State University, Yogyakarta, Indonesia A R T I C L E I N F O Article history: Received 7 April 2017 Received in revised form 11 July 2017 Accepted 16 September 2017 Available online 18 September 2017 Keywords: Electrochemical impedance spectroscopy Square wave anodic stripping voltammetry Skin lightening cosmetics Chloroplatinum(II) complex Hg(II) A B S T R A C T The chemically modified multiwalled carbon nanotubes (MWCNTs) paste electrode with chloroplatinum (II) complex for the determination of mercury is presented. The chloroplatinum(II) complex was characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transforms infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). The capability of the electron transfer rate on the surface of modified electrode evaluated is by electrochemical impedance spectroscopy (EIS). The square wave stripping voltammetry (SWSV) technique was employed to investigate the performance of chloroplatinum(II) complex- MWCNTs paste electrode for determination of mercury. Several operational parameters such as the composition ratios of the electrode, type of supporting electrolyte, pH of the solution, and the SWSV parameters were thoroughly investigated. Under optimal conditions, the linear range obtained was from 5.0 mM to 0.1 mM with limit detection of 3.7 mM. The interference from other heavy metals such as Ca 2+ , Mg 2+ , Ni 2+ , Zn 2+ , Cd 2+ , Co 2+ , Ba 2+ , Mn 2+ , and Ce 3+ did not influence the electrochemical response. The chloroplatinum(II) complex-MWCNTs paste electrode was successfully applied to determine mercury in skin lightening cosmetics with a good recovery (98.9%–101.1%). © 2017 Elsevier Ltd. All rights reserved. 1. Introduction Skin lightening cream is one of the popular cosmetic product among men and women in order to obtain lighter skin tone or as anti-freckle [1,2]. It is known that the application of mercury as an active ingredient in a skin lightening cosmetic has been accepted for centuries [3]. Mercury is known as a neurotoxicant, considered to be one of highly toxic heavy metal ions. According to the Food and Drug Administration (FDA), the maximum concentration of mercury in cosmetics should be less than 1.0 mg g 1 [4]. Even the permitted level of mercury concentration in cosmetics is low, continuous exposure to the skin may lead to a serious health problem such as damage to the brain, kidney, intestines, and nervous system [5–7]. Concerned about the toxicity of these elements at low levels has prompted the development of various selective and sensitive analytical method for its determination. The most common analytical technique employed for the determination of mercury is spectrometry methods such as cold vapor atomic absorption spectrometry [8–10], inductively coupled plasma mass spectrometry [11–13], and atomic fluorescence spectrometry [14–16]. However, these techniques involve expen- sive instruments, high operating cost, complicated procedures, and time-consuming. Comparatively, electrochemical methods, par- ticularly stripping voltammetry have been extensively developed recently due to their low cost, simple, high sensitivity, suitable for in situ analysis and an ability to preconcentrate analyte with advanced electrochemical stripping protocols. Recently, chemically modified electrode by nanomaterials has attracted great attention in the field of electrochemical sensors because of its excellent properties which increase electron transfer rate, catalytic activity and surface area [17–23]. Numerous studies have been done with the determination of mercury by employing different nanomaterials to the electrochemical sensors [24–31]. Previous studies show that the development of chemically * Corresponding author at: Department of Chemistry, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, 35900 Tanjong Malim, Perak, Malaysia. E-mail address: illyas@fsmt.upsi.edu.my (I.M. Isa). http://dx.doi.org/10.1016/j.electacta.2017.09.092 0013-4686/© 2017 Elsevier Ltd. All rights reserved. Electrochimica Acta 253 (2017) 463–471 Contents lists available at ScienceDirect Electrochimica Acta journa l home page : www.e lsevier.com/loca te/ele cta cta