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Chemically-modified electrode for caffeine detection and preparation and application thereof

A chemical modification, caffeine technology, applied in the field of food safety monitoring, can solve the problems of narrow linear range and high detection limit

Inactive Publication Date: 2016-10-12
NORTHWEST NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, there have been many reports on the detection of caffeine by electrochemical methods, but these methods have high detection limits and narrow linear ranges.

Method used

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  • Chemically-modified electrode for caffeine detection and preparation and application thereof
  • Chemically-modified electrode for caffeine detection and preparation and application thereof
  • Chemically-modified electrode for caffeine detection and preparation and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] Embodiment 1, chemical modification electrode

[0043] (1) Pretreatment of the glassy carbon electrode: carefully polish the glassy carbon electrode to the mirror surface with a polishing cloth and Al2O3 powder, remove the Al2O3 powder adsorbed on the surface by ultrasonic cleaning, and then dilute the Al2O3 powder in 1:1HNO 3 , 1:1 ethanol, double-distilled water to clean the surface of the electrode, and dry it in the air. Then dip the electrode into a 1×10 -3 M K 3 Fe(CN) 6 and 0.1M KCl electrolyte solution for cyclic voltammetry scanning, when the redox peak potential separation is less than 80 mV, it means that the electrode grinding and polishing is qualified.

[0044] (2) Preparation of reduced graphene oxide (rGO): (a) First, accurately weigh 2.0 g of graphite powder and place it in a round-bottomed flask, then slowly add 46 mL of concentrated sulfuric acid solution, and stir magnetically in an ice-water bath for 30 min; then place the Slowly add 6.0g of po...

Embodiment 2

[0047] Example 2, using chemically modified electrodes to detect CAF in beverages

[0048] In order to evaluate the practicability of the modified electrode, the prepared modified electrode 3DAuNPs-cys / Nafion-rGO was used to detect CAF in local commercial cola and functional drinks by differential pulse voltammetry. With 0.1M H containing caffeine at pH=2.0 2 SO 4 The buffer solution is an electrolyte, and the scan rate is 90~190 mV, the electrode potential is -0.6~2.1V, and the number of scan cycles is 8~10. According to the linear relationship between the concentration of CAF and its oxidation peak current, the concentration of CAF in each functional beverage is determined. , and the standard addition method was used to measure the standard addition recovery rate, and the measurement results are shown in Table 1. It can be concluded from the test results that the modified electrode can detect CAF in commercial cola and functional drinks, and the recovery rate is between 96...

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Abstract

The invention provides a chemically-modified electrode for caffeine detection. The chemically-modified electrode for caffeine detection is obtained by modifying a polished glassy carbon electrode with poly-gold nanometer particles, L-cysteine, Nafion and reduced graphene oxide in sequence. The chemically-modified electrode serves as a detection electrode, a 0.1M H2SO4 buffering solution containing caffeine with the pH being 2.0 serves as an electrolyte, the differential pulse voltammetry is utilized, scanning is carried out for 8-10 turns under the scanning speed of 90-190 mV and the electrode potential of -0.6-2.1 V, the concentration of CAF and the oxidation peak current of CAF are in a good linear relation, and the detection limit is 1.0*10<-9>M. Thus, the electrode shows very high sensitivity, stability, repeatability, long-term stability and low detection limit on detection of caffeine, no pretreatment is needed when the electrode is used for detecting caffeine in drinks, and the electrode can be effectively used for detecting the content of caffeine in drinks sold on the market.

Description

technical field [0001] The present invention relates to a chemically modified electrode for caffeine detection, in particular to a chemically modified electrode modified by a 3D gold nanoparticle-poly-L-cysteine / Nafion / reduced graphene oxide composite film and its preparation; The invention also relates to the application of the chemically modified electrode in detecting caffeine, which belongs to the technical field of food safety monitoring. technical background [0002] Caffeine is the main alkaloid in plants, which belongs to xanthine derivatives and mainly exists in coffee beans, cocoa beans, cola nuts, tea leaves and other plants. In people's daily life, an appropriate amount of caffeine is usually used as a psychoactive substance of the human body and has many important physiological effects on the human body, such as stimulating nerves, diuresis, and relieving headaches. However, if caffeine is used excessively, it will have some adverse effects on the human body, s...

Claims

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Application Information

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IPC IPC(8): G01N27/48G01N27/30
CPCG01N27/308G01N27/48
Inventor 杨武安惠惠郭昊卢秀黄萍林丹
Owner NORTHWEST NORMAL UNIVERSITY
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