Analytical chemistry
Ghobad Mansouri; Mohammd Bagher Gholivand; Zarrin Eshaghi
Abstract
A single-use electrochemical sensor using ionic liquid mediated hollow fiber-graphite working electrode was fabricated for the first time. The screening tool was developed by coupling this electrode with differential pulse voltammetry (DPV) for in-situ pre-concentration and determination of Zn(II) and ...
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A single-use electrochemical sensor using ionic liquid mediated hollow fiber-graphite working electrode was fabricated for the first time. The screening tool was developed by coupling this electrode with differential pulse voltammetry (DPV) for in-situ pre-concentration and determination of Zn(II) and Cu(II). In our plot, porous polypropylene hollow fiber membrane was divided into pieces of 2 cm, then fiber's lumen and pores were satiated with homogeneous mixture of reduced graphene oxide (rGO) and three types used ionic liquids:(1-ethyl-3-methylimidazolium tetrafuoroborate), (1-butyl-3-methylimidazoliumhexafluorophosphate) and (1-butyl-2,3-dimethylimidazolium hexafluorophosphate) individually. Thereafter, a pencil graphite rod was placed inside the fiber. Fabricated sensors were used for single-step simultaneous purification and determination of Zn(II) and Cu(II) ions from water samples. The response surface method (RSM) was used as the basis of the design and analysis of the experiments. Parameters that were mostly important in the separation part of the study, such as: molar mass of ionic liquids, amount of nanoparticle and sonication time have been investigated. Analysis of variance (ANOVA) and RSM contour plots were presented for effect of all factors (input parameters) on the maximum current of differential pulse voltammetry (DPV) peaks (output responses). The results disclosed that the metal removal was impressed by the molar mass of ionic liquids, amount of nanoparticle and sonication time respectively. The efficiency specifications of this procedure were evaluated by calculating precision and response linearity. Under the optimal experimental conditions linear concentration ranges of 0.9–550µgL-1 and 0.7–500 µgL-1 were obtained for Zn(II) and Cu(II) ions respectively. The reported limit of detection for Zn(II) and Cu(II) were 0.27 and 0.21µgL-1 with relative standard deviations (RSD) 3.2%, and 4.4%, respectively. In addition, this sensor was successfully applied to real water samples.
Analytical chemistry
Fatemeh Moeinpour; Zarrin Eshaghi
Volume 7, Issue 2, pp. 90-159, Serial No. 23 , April 2019, , Pages 126-138
Abstract
The objective of this study is to design a simple, fast, sensitive and single-use electrode with the simultaneous capability of preconcentration and measuring, for application in a three-electrode voltammetry system to identify and measure the heavy metal cadmium. The design process of this sensor consists ...
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The objective of this study is to design a simple, fast, sensitive and single-use electrode with the simultaneous capability of preconcentration and measuring, for application in a three-electrode voltammetry system to identify and measure the heavy metal cadmium. The design process of this sensor consists of several stages. The polyurethane foam and multi walled carbon nanotubes nanoparticles were functionalized and the new nanocomposite was synthesized that with the help of an organic solvent, established on the pencil graphite electrode that was covered with hollow fiber. In this work, for the first time, the organic solvent was employed instead of ionic liquid. The designed sensor was used to detect and measure heavy metal cadmium through differential pulse voltammetry technique, which appearance of a sharp peak at -0.82 V indicates the presence of cadmium. It was found that the presence of air molecules as the analyte carrier (between hollow fiber cavities and in fixed nanocomposite on the graphite) instead of organic solvents or ionic liquids was desirable. All the synthesis stages of nanocomposite were analyzed by infrared spectroscopy. Finally, the nanocomposite morphology was obtained with a Scanning Electron Microscope. A calibration curve was drawn and linear response with a range of 2.39 to 47.6 µM was plotted. The LOD of the designed sensor was 0.399 µM for cadmium. The mentioned sensor was used to recognize and analyte measurement in real biological samples of urine, nail, and wastewater of the laboratory.
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