Determination of caffeine content in tea based on poly(safranine T) electroactive film modified electrode

Guo, Sujuan; Zhu, Qianqian; Yang, Baocheng; Wang, Jing; Ye, Baoxian

doi:10.1016/j.foodchem.2011.05.095

Cited by 63 publications

(29 citation statements)

References 29 publications

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“…Caffeine, which is natural alkaloid or xanthine alkaloid, commonly found in coffee beans, tea leaves, cocoa beans and cola nuts have been reported to be the active antimicrobial constituent (Nawrot et al, 2003;Nonthakaew et al, 2015). However, the amount of caffeine varies per plant products and are equally affected by extraction method employed (Guo et al, 2011;Salinas-Vargas et al, 2014). Caffeine evolved as a chemical produced by plants to kill microbes and insect parasites.…”

Section: Introductionmentioning

confidence: 99%

Antimicrobial and Antihaemolytic Activities of Crude Extracts of Some Commonly Used Tea and Coffee in Nigeria

Olajubu

2017

jtsr

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Current indiscriminate abuse of existing antibiotics in clinical and veterinary treatments lead to an upsurge in antimicrobial resistant strains of microorganisms and aggressive search for alternatives which are readily available, less expensive with little or no side effect. Tea and Coffee are beverages consumed daily in every household in Nigeria. This study examines the antimicrobial and anti-haemolytic properties of commonly available Tea and Coffee in Nigerian market. The antimicrobial potencies of the extracts were assessed through disc diffusion method on pathogens of both man and animal origin while the anti-haemolytic assay was carried out through colorimetric method. The extracts were slightly acidic at full strength and no antifungal property was observed. Broad spectrum and bactericidal effects were observed against Staphylococcus aureus, Salmonella pullorum, Shigella dysenteriae and Streptococcus pneumonia. These activities were concentration dependent. Very poor activity was observed against Escherichia coli. Bactericidal rate of coffee was at 6hrs but ranged between 18 and 24 hrs for tea extracts. Tea extracts greatly inhibited the haemolytic potential of alpha toxins while coffee performed poorly. Tea and Coffee could thus serve as supportive treatment for some bacterial infections without fear of side effects, since they are naturally taken as daily beverages.

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Section: Introductionmentioning

confidence: 99%

Antimicrobial and Antihaemolytic Activities of Crude Extracts of Some Commonly Used Tea and Coffee in Nigeria

Olajubu

2017

jtsr

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“…Electroanalytical methods have been commonly exploited as cheap, speedy, and simple options to modern separation and spectral methods. Over the years, to improve the sensitivity and long-term stability of the electrodes, the bare electrodes altered with several electrode modifiers such as nafion, conducting polymers, molecularly imprinted polymers, metal nanoparticles, carbon nanotubes (CNTs), and graphene were used for the individual determination of CAF (Švorc 2013;Brunetti et al 2007;Sun et al 2011a;Yang et al 2010;Sun et al 2011b;Amare and Admassie 2012;Wang et al 2004;Wei et al 2009;Xiong et al 2013;Lu et al 2012;Alizadeh et al 2010;Aklilu et al 2008;Ly et al 2008;Ly et al 2009;Habibi et al 2012;Martínez-Huitle et al 2010;Guo et al 2011;Yardım et al 2013) and VAN (Zheng et al 2010;Bettazzi et al 2006;Luque et al 2000;Peng et al 2012;Kong et al 2010;Deng et al 2015;Shang et al 2014;Luo and Liu 2012;Xinying 2014;Chethanaa et al 2012). It was noted that determination of CAF has predominantly been performed by voltammetric methods (Švorc 2013).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Electrochemical Determination of Caffeine and Vanillin by Using Poly(Alizarin Red S) Modified Glassy Carbon Electrode

2016

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Poly(alizarin red S) conducting polymer was prepared on glassy carbon electrode (GCE) surfaces, and the functionalized electrode was used for the simultaneous determination of caffeine (CAF) and vanillin (VAN). The peak potential separation for caffeine and vanillin was about 600 mV in 0.1 M acetate buffer solution (pH 4.0). The peak currents for the oxidation of both CAF and VAN are increased at poly(alizarin red S) (poly(ARS)) functionalized electrode, which makes it suitable for simultaneous detection of these compounds. The square wave voltanmmetry peak current of VAN was linear with the concentration of VAN from 0.5 to 250 μM in the presence of 250 μM CAF. The detection limit of VAN was found to be 0.06 μM in the presence of CAF. At the same time, the peak current of CAF was linear with the concentration of CAF from 10 to 450 μM with a detection limit of 0.8 μM (S/N = 3) in the presence of 30 μM VAN. The poly(ARS) functionalized GCE has good reproducibility and high stability. In addition, the proposed method was successfully applied to determine CAF and VAN in energy drink and vanilla sugar samples with good results.

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“…The conductive polymers synthesised by electropolymerisation of azines and phenazines can serve as redox mediators [3][4][5][6][7][8]. Active sites of these dyes facilitate the electrochemical deposition of electroactive species.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, some functional groups of the polymers such as -NH and -COOH allow selective molecular interactions between the polymer film and the target molecule. The polymer-modified electrodes have been widely used in electrochemical sensors and biosensors for the investigation of the characteristics of some molecules such as Lcysteine and L-tyrosine [3], dopamine [4,5], caffeine [6], nitric oxide [7] and hydrogen peroxide [8].…”

Section: Introductionmentioning

confidence: 99%

Poly(acridine orange)-modified glassy carbon electrodes: electrosynthesis, characterisation and sensor application with uric acid

2014

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Poly(acridine orange) was electropolymerised on glassy carbon electrodes by potential cycling in phosphate buffer solution at pH 5.5, 6.0, 7.0 and 8.0. Electrochemical behaviour of the modified electrodes was studied by cyclic voltammetry in phosphate buffer solution at various pHs and found that the best polymer film formation was obtained at pH 5.5. Quantitative determination of uric acid was achieved by cyclic voltammetry, differential pulse voltammetry (DPV) and fixed-potential amperometry in phosphate buffer solution at pH 5.5. Anodic peak currents were linearly proportional to concentration of uric acid in the range 1-75 lM for cyclic voltammetry, 0.4-75 lM for DPV and 0.04-5.3 lM for amperometry. Detection limits were 3.7 9 10 -1 , 9.7 9 10 -2 and 9.5 9 10 -3 lM for cyclic voltammetry, DPV and amperometry, respectively. The modified electrodes exhibited good sensitivity, wide linear range and good stability. There is no interference from substances commonly present in natural samples.

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Determination of caffeine content in tea based on poly(safranine T) electroactive film modified electrode

Cited by 63 publications

References 29 publications

Antimicrobial and Antihaemolytic Activities of Crude Extracts of Some Commonly Used Tea and Coffee in Nigeria

Antimicrobial and Antihaemolytic Activities of Crude Extracts of Some Commonly Used Tea and Coffee in Nigeria

Simultaneous Electrochemical Determination of Caffeine and Vanillin by Using Poly(Alizarin Red S) Modified Glassy Carbon Electrode

Poly(acridine orange)-modified glassy carbon electrodes: electrosynthesis, characterisation and sensor application with uric acid

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