Journal
ELECTROANALYSIS
Volume 31, Issue 2, Pages 350-356Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/elan.201800621
Keywords
Caffeine; Electroanalysis; Attapulgite; Nafion; Film modified electrode
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Funding
- The World Academy of Sciences (TWAS) [16-515RG/CHE/AF/AC_G-FR3240293302]
- Alexander von Humboldt Foundation (Germany)
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In the present work, a simple and economic analytical method based on attapulgite/nafion coated glassy carbon electrode (AT/Naf/GCE) has been developped for the electrochemical determination of caffeine. Prior to its use, the ionic exchange properties and conductivity of AT/Naf/GCE were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Caffeine gave an irreversible oxidation peak around +1.41V (vs Ag/AgCl reference electrode) in 0.1M H2SO4 at pH1.5. The peak current varied linearly with the square root of the scan rate, showing that the transfer process is controlled by diffusion. The heterogeneous rate constant, the transfer coefficient and the number of electrons involved were calculated. Upon optimization of key analytical parameters involved in the electroanalysis of caffeine by DPV, the recorded oxidation peak current varied linearly with caffeine concentration in the range from 0.1 to 4m, leading to a detection limit of 4.57x10(-8)M (S/N=3). The developed electrode exhibited good stability and was easily regenerated. The effect of some important potential interfering compounds (ascorbic acid, dopamine, uric acid, sulphite ions and glucose) on the signal of caffeine was also examined. The obtained electrode was successfully employed in the determination of caffeine content in a commercial drug.
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