z Analytical Chemistry Developing an Electrochemical Sensor Based on Modified Siliceous Mesocellular Foam for Efficient and Easy Monitoring of Cadmium Ions Majid K. Bojdi, [a] Mohammad Behbahani,* [b] and Somaye Ranjbari [a] In response to a mandatory demand to introduce sensitive technique to measure cadmium ion in ultra-trace concentra- tion, an electrochemical sensor by applying modified siliceous mesocellular foam (S-MCF) with diphenylthiocarbazone as electrode material is developed. Several instrumental analysis including Fourier transform infrared spectrometry, nitrogen adsorption-desorption examination, scanning electron micro- scopy, thermal evaluation and elemental analysis were applied to characterize the prepared electrode material. In the work, the prepared electrode with introduced mesoporous material is conjugated with differential pulse anodic stripping voltamme- try (DP-ASV) for ultra-trace measurement of Cd 2 + ions. Cadmium ions interact strongly with active sites of diphenylth- iocarbazone and a negative potential (-0.9 V) was applied to reduce these ions. Based on the specific characteristic of the electrochemical sensor, this electrode material was applied to pre-concentrate target ions on the modified electrode by the prepared mesoporous material. In order to measure Cd 2 + at ultra-trace concentrations, differential pulse-ASV was utilized to oxidize the reduced Cd ions. Two dynamic linear range (DLR) for measurement of cadmium ions at ultra-trace concentrations were seen within ranges of 0.01 to 1.0 nmol L 1 (with sensitivity of 13.23 μA/nmol L 1 ) and 1.0 nmolL 1 to 10.0 nmol L 1 (with sensitivity of 0.23 μA/nmol L 1 ). The method detection limit (MDL) of 2.5 pmol L 1 was acquired. 1. Introduction Natural water contamination by toxic heavy metals is very important for any environmental chemist and consequently, has gained exceptional consideration because of detrimental and bioaccumulation factor in the food matrices. [1–3] Based on the developing industrialization of modern life and agriculture, cadmium has emerged as one of its deleterious byproducts. [4–6] Cadmium, based on its toxicity, can adversely affect different biological systems. [7,8] and accordingly, wide researches have been focused on the developing and using of various measure- ment techniques for quantification of Cd ions. Hence, it is favorable to design selective, ordinary, eco-friendly and efficient methods to determine Cd ions in biological and environmental matrices. [9–13] Although ICP-MS, ICP-OES, AAS, etc., are sensitive methods, they are expensive, less efficient, time-consuming, and indecorous for rapidly determination of toxic ions for the evaluation of polluted sites. [14–16] More recently, Jiang et al. developed an advanced method in which they used electrochemical laser induced breakdown spectro- scopy to quantify the exact amount of cadmium ions. In this work the authors can determine cadmium ions at trace levels (5.6 μgL 1 ) with good precision. [17] In another report, research- ers showed that thiol and amino-functionalized porous Si nanowires have been demonstrated to selectively detect Cd(II) and Pb(II) with high sensitivity using square wave anodic stripping voltammetry (SWASV). It can be found that the stripping currents increase with the increase of the concen- trations of Cd(II). According to the relationship between stripping current and concentration, a well-defined linear curve has been presented in the range from 5 to 250 nM. [18] The stripping measurement as an electrochemical detection techni- que is an acceptable candidate as another method. Anodic-SV is a selective and sensitive method and thus is an enchanting technique based on electrochemical measurement of toxic ions at trace concentrations. One of other advantage of ASV (Anodic stripping voltammetry) over the other analytical techniques is the easiness of the needed gadget, which is approximately inexpensive, portable, proper for automation, and requires low electrical power consumption. [19–21] Normally, the efficiency of ASV is highly affected by the applied material for the sensor. A good material for preparing of electrode must possess characteristics like as electrochemical and chemical inertness, appropriate mechanical characteristics, low ohmic resistance, low background of current, high over-potential for oxygen and hydrogen (wide potential window) and simplicity of surface regeneration of the sensor. The electrodes based on mercury have been extremely applied in anodic-SV of cadmium species according to their broad potential window at negative values. [a] Dr. M. K. Bojdi, S. Ranjbari Department of Chemistry, Faculty of Science, University of Birjand, Birjand, South Khorasan, Iran [b] Dr. M. Behbahani Faculty of Engineering, Shohadaye Hoveizeh University of Technology, Dasht-e Azadegan, Susangerd, Iran Tel.: + 98 6136751021 Fax: + 98 61 36751020 E-mail: m.behbahani@shhut.ac.ir mohammadbehbahani89@yahoo.com Supporting information for this article is available on the WWW under https://doi.org/10.1002/slct.202000553 ChemistrySelect Full Papers doi.org/10.1002/slct.202000553 6617 ChemistrySelect 2020, 5, 6617 – 6625 © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim