Applicability of Cork as Novel Modifiers to Develop Electrochemical Sensor for Caffeine Determination.

Mayra Monteiro,Elisama Dos Santos,Carlos Martínez-Huitle,Vítor Vilar,Marco Quiroz,Djalma Da Silva

doi:10.3390/ma14010037

Abstract

This study aims to investigate the applicability of a hybrid electrochemical sensor composed of cork and graphite (Gr) for detecting caffeine in aqueous solutions. Raw cork (RAC) and regranulated cork (RGC, obtained by thermal treatment of RAC with steam at 380 °C) were tested as modifiers. The results clearly showed that the cork-graphite sensors, GrRAC and GrRGC, exhibited a linear response over a wide range of caffeine concentration (5–1000 µM), with R2 of 0.99 and 0.98, respectively. The limits of detection (LOD), estimated at 2.9 and 6.1 µM for GrRAC and GrRGC, suggest greater sensitivity and reproducibility than the unmodified conventional graphite sensor. The low-cost cork-graphite sensors were successfully applied in the determination of caffeine in soft drinks and pharmaceutical formulations, presenting well-defined current signals when analyzing real samples. When comparing electrochemical determinations and high performance liquid chromatography measurements, no significant differences were observed (mean accuracy 3.0%), highlighting the potential use of these sensors to determine caffeine in different samples.

Highlights

Caffeine (1,3,7-trimethylxanthine) is used as a flavoring agent and stimulating agent of the central nervous system [1,2]
The caffeine concentrations measured in real samples with the GrRAC sensor were very similar to those determined by HPLC used as an independent method, and comparable to those reported in the nutritional table of the samples
Sensors arewhen characterized by greater caffeine using the way cork to sensor is effective, higherThese current signals analyzing sensitivity and reproducibility than the conventional unmodified graphite sensor, and solutions with higher analyte levels

Summary

Introduction

Caffeine (1,3,7-trimethylxanthine) is used as a flavoring agent and stimulating agent of the central nervous system [1,2]. High doses of caffeine over time can promote irritability, anxiety, mutation effects, tremors, bone mass loss and sometimes cardiovascular disease [4]. It is present in cola-based beverages, coffee, tea, energy drinks and pharmaceutical formulations. The development of electrochemical sensing tools for various applications is receiving great attention [5,6,7,8,9,10,11,12,13,14,15,16,17] Due to their inherent specificity, rapid measurement procedures, high accuracy, high sensitivity and simplicity of preparation, these measuring devices allow monitoring of different species in a satisfactory way. The low cost and the absence of toxic solvents, necessary in other techniques such as chromatography and spectrophotometry, should be mentioned [18,19]

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Conclusion