Development of a voltammetric sensor based on a molecularly imprinted polymer (MIP) for caffeine measurement

• Published in: Electrochimica acta 2010-02, Vol.55 (5), p.1568-1574
• Main Authors: Alizadeh, Taher, Ganjali, Mohamad Reza, Zare, Mashaalah, Norouzi, Parviz
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Biological and medical sciences; Caffeine; Carbon; Carbon paste electrode; Chemistry; Electrochemical methods; Electrochemical sensor; Electrodes; Exact sciences and technology; Food industries; Fundamental and applied biological sciences. Psychology; Imprinted polymers; Molecularly imprinted polymer; Non alcoholic beverage industries and mineral waters; Pastes; Recognition; Sensors; Voltammetry
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2009.09.086

A new voltammetric sensor for caffeine measurement is introduced. A caffeine-selective molecularly imprinted polymer (MIP) and a non-imprinted polymer (NIP) were synthesized and then used for carbon paste (CP) electrode preparation. The MIP, embedded in the carbon paste electrode, functioned as a selective recognition element and a pre-concentrator agent for caffeine determination. The prepared electrode was used for caffeine measurement via a three-step procedure including analyte extraction in the electrode, electrode washing and electrochemical measurement of caffeine. The MIP-CP electrode showed very high recognition ability in comparison to NIP-CP. It was shown that electrode washing after caffeine extraction led to enhanced selectivity. Differential pulse voltammetry for caffeine determination was more effective than square wave voltammetry. Some parameters affecting sensor response were optimized, and a calibration curve was then plotted. A linear range of 6 × 10 −8 to 2.5 × 10 −5 mol L −1 was obtained. The detection limit of the sensor was calculated to be equal to 1.5 × 10 −8 mol L −1. This sensor was used successfully for caffeine determination in spiked beverage and tea samples.