A Simple and Sensitive Method for the Voltammetric Analysis of Theobromine in Food Samples Using Nanobiocomposite Sensor
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Theobromine (TB) is one of important natural methylxanthine alkaloids in plants and their products, but there were few reports on the electrochemistry of TB, especially electrochemical measurements using chemically modified electrode owing to its poor detectability. In this work, a simple and sensitive method for the voltammetric analysis of TB in green tea, chocolate, and coffee samples was successfully realized using nanobiohybrid sensor based on glassy carbon electrode (GCE) modified by both carboxyl-functionalized multiwalled carbon nanotubes (fMWCNTs) and soluble biopolymer sodium salt of carboxymethylcellulose (CMC). Water-dispersible nanonbiohybrids with fMWCNTs were successfully prepared using CMC assist, and CMC-fMWCNTs were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, transmission electron microscope, electrochemical impedance spectroscopy, and cyclic voltammetry. CMC-fMWCNTs/GCE showed enlarged electrochemically active surface area, good electrode stability, and enhanced electrocatalytic activity. The voltammetric behavior of TB demonstrated an irreversible electrochemical oxidation reaction involving two electrons and two protons, which could detect TB in a wider linear range from 0.5 to 80 μM with a lower limit of detection (LOD) of 0.21 μM. The developed method displayed a high sensitivity, low LOD, good sensing stability, remarkable feasibility, and satisfactory practicality.
KeywordsVoltammetric sensor Nanobiocomposite Theobromine Carbon nanotube Carboxymethyl cellulose
The authors would like to appreciative of financial support from the National Science Foundation of China (31660492, 51662014), Jiangxi Provincial Department of Education (GJJ150428), China Postdoctoral Science Foundation (2015M571987), Special Funds for Jiangxi Province Postdoctoral Research Funds (2015KY44), and Jiangxi Provincial Innovation Fund of Postgraduates (No. YC2016-S183).
Compliance with Ethical Standards
Conflict of Interest
Yingqiong Peng declares that she has no conflict of interest. Wenjuan Zhang declares that she has no conflict of interest. Juan Chang declares that she has no conflict of interest. Yaoping Huang declares that she has no conflict of interest. Li Chen declares that she has no conflict of interest. Hong Deng declares that he has no conflict of interest. Zhong Huang declares that he has no conflict of interest. Yangping Wen declares that he has no conflict of interest.
This article does not contain any studies with human or animal subjects. This is an original research article that has neither been published previously nor considered presently for publication elsewhere. All authors named in the manuscript are entitled to the authorship and have approved the final version of the submitted manuscript.
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