ZIF-67/g-C3N4-Modified Electrode for Simultaneous Voltammetric Determination of Uric Acid and Acetaminophen with Cetyltrimethylammonium Bromide as Discriminating Agent

In the present paper, the ZIF-67/g-C3N4 composite was synthesized and utilized as a modifier for a glassy carbon electrode for the simultaneous voltammetric determination of uric acid (URA) and acetaminophen (ACE) with cetyltrimethylammonium bromide (CTAB) as a discriminating agent. The composite was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption/desorption isotherms. The obtained ZIF-67/g-C3N4 composite exhibits good textural properties (specific surface area: 75 m2·g−1) and is stable in water with a pH range of 3 to 10. The ZIF-67/g-C3N4-modified electrode combined with CTAB as a discriminating agent possesses excellent catalytic electrochemistry towards URA and ACE with well-defined electrochemical responses. The electrochemical kinetics study is also addressed. The linear relation of the oxidation peak current of URA and ACE and the concentration ranging from 0.2 μM to 6.5 μM provide a detection limit of 0.052 μM for URA and 0.053 μM for ACE. The proposed method is well-suited to simultaneously analyze URA and ACE in human urine with comparable results with HPLC.

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Simultaneous voltammetric determination of ascorbic acid and uric acid using a Nafion/multi-wall carbon nanotubes composite film-modified electrode

Journal of Solid State Electrochemistry ◽

10.1007/s10008-010-1088-7 ◽

2010 ◽

Vol 15 (1) ◽

pp. 161-166 ◽

Cited By ~ 15

Author(s):

Gang Li ◽

Suling Yang ◽

Lingbo Qu ◽

Ran Yang ◽

Jianjun Li

Keyword(s):

Carbon Nanotubes ◽

Ascorbic Acid ◽

Uric Acid ◽

Composite Film ◽

Modified Electrode ◽

Voltammetric Determination ◽

Multi Wall Carbon Nanotubes ◽

Simultaneous Voltammetric Determination

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Simultaneous Voltammetric Determination of Uric Acid, Xanthine, and Hypoxanthine Using CoFe2O4/Reduced Graphene Oxide-Modified Electrode

Journal of Nanomaterials ◽

10.1155/2020/9797509 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Nguyen Thi Vuong Hoan ◽

Nguyen Ngoc Minh ◽

Nguyen Thi Hong Trang ◽

Le Thi Thanh Thuy ◽

Cao Van Hoang ◽

...

Keyword(s):

Uric Acid ◽

Graphene Oxide ◽

Reduced Graphene Oxide ◽

Modified Electrode ◽

Photoelectron Spectroscopy ◽

Cobalt Ferrite ◽

Simultaneous Detection ◽

X Ray ◽

Reduced Graphene

In the present paper, the synthesis of cobalt ferrite/reduced graphene oxide (Co2Fe2O4/rGO) composite and its use for the simultaneous determination of uric acid (UA), xanthine (XA), and hypoxanthine (HX) is demonstrated. Cobalt ferrite hollow spheres were synthesized by using the carbonaceous polysaccharide microspheres prepared from a D-glucose solution as templates, followed by calcination. The CoFe2O4/rGO composite was prepared with the ultrasound-assisted method. The obtained material was characterized by using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, EDX elemental mapping, and nitrogen adsorption/desorption isotherms. The electrochemical behavior of UA, XA, and HX on the CoFe2O4/rGO-modified electrode was studied with cyclic voltammetry and differential pulse voltammetry (DPV). The modified electrode exhibits excellent electrocatalytic activity towards the oxidation of the three compounds. The calibration curves for UA, XA, and HX were obtained over the range of 2.0–10.0 μM from DPV. The limits of detection for UA, XA, and HX are 0.767, 0.650, and 0.506 μM, respectively. The modified electrode was applied to the simultaneous detection of UA, XA, and HX in human urine, and the results are consistent with those obtained from the high-performance liquid chromatography technique.

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Graphitic Nitrogen in Carbon Catalysts Important for the Reduction of Nitrite Revealed by 15N NMR Spectroscopy at Natural Abundance

10.26434/chemrxiv.12906227.v1 ◽

2020 ◽

Author(s):

Zheng Chen ◽

Aleksander Jaworski ◽

Jianhong Chen ◽

Tetyana Budnyak ◽

Ireneusz Szewczyk ◽

...

Keyword(s):

Electron Microscopy ◽

Photoelectron Spectroscopy ◽

Reduction Reaction ◽

Nitrite Reduction ◽

15N Nmr ◽

Carbon Catalyst ◽

X Ray ◽

Wide Range ◽

Alkaline Conditions

Metal-free nitrogen-doped carbon is considered as a green functional material, but the structural determination of the atomic positions of nitrogen remains challenging. We recently demonstrated that directly-excited solid state 15N NMR (ssNMR) spectroscopy is a powerful tool for the determination of such positions in an N-doped carbon at natural 15N isotope abundance. Here we present a green chemistry approach to the synthesis of N-doped carbon using cellulose as precursor, and a study of the catalytic properties and atomic structures of the related catalyst. The N-doped carbon (NH3) was obtained by oxidation of cellulose with HNO3 followed by ammonolysis at 800°C. It had a N content of 6.5 wt.% and a surface area of 557 m2 g–1, and 15N ssNMR spectroscopy provided evidence for graphitic nitrogen besides of regular pyrrolic and pyridinic nitrogen. This structure determination enabled probing the role of graphitic nitrogen for electrocatalytic reactions, such as the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and nitrite reduction reaction. The N-doped carbon catalyst (NH3) had higher electrocatalytic activities in OER and HER under alkaline conditions and a higher activity for nitrite reduction, as compared with a catalyst prepared by carbonization of the HNO3-treated cellulose in N2. The electrocatalytic selectivity for nitrite reduction of the N-doped carbon catalyst (NH3) was directly related to the graphitic nitrogen functions. Complementary structural analysis by means of 13C and 1H ssNMR, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and low-temperature N2 adsorption were preformed and provided support to the findings. The results show that directly-excited 15N ssNMR at natural 15N abundance is generally capable to provide information on N-doped carbon materials, and it is expected that the approach can be applied to a wide range of solids with an intermediate amount of N atoms.

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