Bare carbon electrodes as simple and efficient sensors for the quantification of caffeine in commercial beverages.

Luca Redivo,Marina Resmini,Luciano Navarini,Ĺubomír Švorc,Elisabetta De Angelis,Miroslav Stredanský

doi:10.1098/rsos.172146

Abstract

Food quality control is a mandatory task in the food industry and relies on the availability of simple, cost-effective and stable sensing platforms. In the present work, the applicability of bare glassy carbon electrodes for routine analysis of food samples was evaluated as a valid alternative to chromatographic techniques, using caffeine as test analyte. A number of experimental parameters were optimized and a differential pulse voltammetry was applied for quantification experiments. The detection limit was found to be 2 × 10−5 M (3σ criterion) and repeatability was evaluated by the relative standard deviation of 4.5%. The influence of sugars, and compounds structurally related to caffeine on the current response of caffeine was evaluated and found to have no significant influence on the electrode performance. The suitability of bare carbon electrodes for routine analysis was successfully demonstrated by quantifying caffeine content in seven commercially available drinks and the results were validated using a standard ultra-high performance liquid chromatography method. This work demonstrates that bare glassy carbon electrodes are a simple, reliable and cost-effective platform for rapid analysis of targets such as caffeine in commercial products and they represent therefore a competitive alternative to the existing analytical methodologies for routine food analysis.

Highlights

Novel technological developments applicable to the area of food quality and safety are driven by strong public interests [1] as well as by the growing numbers of new regulations introduced by food agencies, to ensure that standards are upheld in commercialized products [2]
Most analytical techniques and protocols developed for these purposes allow sensitive and precise quantitative analysis, and rely on equipment-based systems such as capillary electrophoresis (CE) [3,4], gas chromatography (GC) [5,6], high-pressure liquid chromatography (HPLC) [7,8], infrared (IR)-Raman spectroscopy [9,10], surface-enhanced Raman spectroscopy (SERS) [11,12], nuclear magnetic resonance (NMR) [13,14] and UV spectroscopy [15,16]
Sulfuric acid was used at 0.1 M as the optimal concentration, as it gave the highest S/N ratio

Summary

Introduction

Novel technological developments applicable to the area of food quality and safety are driven by strong public interests [1] as well as by the growing numbers of new regulations introduced by food agencies, to ensure that standards are upheld in commercialized products [2]. Most analytical techniques and protocols developed for these purposes allow sensitive and precise quantitative analysis, and rely on equipment-based systems such as capillary electrophoresis (CE) [3,4], gas chromatography (GC) [5,6], high-pressure liquid chromatography (HPLC) [7,8], infrared (IR)-Raman spectroscopy [9,10], surface-enhanced Raman spectroscopy (SERS) [11,12], nuclear magnetic resonance (NMR) [13,14] and UV spectroscopy [15,16] These techniques are accurate and selective, but require expensive instruments and highly trained workers and in some cases additional steps due to sample pre-treatment [17]. Some successful examples of an electrochemical sensor based on bare GCE were recently reported in the literature, in particular in the area of pharmaceutical formulation analysis [34,35,36,37]

Methods

Results

Conclusion