Non‐enzymatic Electrochemical Sensor for the Simultaneous Determination of Xanthine, its Methyl Derivatives Theophylline and Caffeine as well as its Metabolite Uric Acid

Abstract

Xanthine and its methyl derivatives, theophylline and caffeine are purines which find important roles in biological systems. The simultaneous voltammetric behaviour of these purines has been studied on a glassy carbon electrode modified with an electropolymerised film of para amino benzene sulfonic acid. Well defined and well separated peaks were obtained for the oxidation of xanthine, theophylline and caffeine on the polymer modified electrode in the square wave mode. The experimental requirements to obtain the best results for individual as well as simultaneous determination were optimised. The signal for the electro‐oxidation was found to be free of interferences from each other in the range 0.9 – 100 μM in the case of xanthine and from 10–100 μM in the case of theophylline and caffeine with detection limits 0.35 μM, 7.02 μM and 11.95 μM respectively. The simultaneous determination of uric acid, the final metabolic product of xanthine oxidation in biological systems could also be accomplished along with xanthine, theophylline and caffeine atphysiological pH. The mechanistic aspects of the electro‐oxidation on the polymer modified electrode was also studied using linear sweep voltammetry. Chronoamperometry was employed to determine the diffusion coefficient of these xanthines. The developed sensor has been successfully demonstrated to be suitable for the determination of these compounds in real samples without much pre‐treatment.

Simultaneous Quantification of Antioxidants Paraxanthine and Caffeine in Human Saliva by Electrochemical Sensing for CYP1A2 Phenotyping

“…In the reverse scan using the GC electrode, no reduction peak was observed, suggesting that the electron transfer during the oxidation of PX and CAF is completely irreversible. Although similar behavior has been reported for CAF [ 57 , 63 ], to the best of our knowledge this is the first report of the electrochemical characterisation of PX.…”

Simultaneous Trace Electrochemical Determination of Xanthine Theophylline and Theobromine with a Novel Sensor Based on a Composite Including Metal Oxide Nanoparticle Multi‐walled Carbon Nanotube and Nano‐Na‐montmorillonite Clay

“…All validation and regression parameters are represented in Table 1. Although there are studies involving the analysis of individual [2,4,5,6,14] or binary [1,7] mixtures of these compounds in the literature, we mentioned that there is only one publication in the literature that includes the simultaneous determination of these three biomolecules. In that study [8], LOD values for XT, TP, and TB were given as 0.09 μM, 0.56 μM, and 0.75 μM, respectively.…”

“…Xanthine derivatives are compounds with a purine core that stimulant the central nervous system. The purine molecules include xanthine (XT), theophylline (TP), theobromine (TB) as well as caffeine (CF), and uric acid (UA) [1]. XT (IUPAC name: 3,7-dihydropurine-2,6dione) is chemically known as 2,6-dihydroxy purine and also an intermediate product in the conversion metabolism of purine, adenine, and guanine to uric acid (UA) [2,3].…”

“…Thus, the reliable analytical method for the simultaneous determination of these three biomolecules is also needful to support measurements in the pharmaceutical, clinical diagnostic, and food analysis areas at the lower limit of detection (LOD) values, with high selectivity and rapidity. Spectroscopy [9], spectrophotometry [10], chromatography [11,12], and electrochemistry [1,8] methods have been applying in the literature to achieve simultaneous detection of purine molecules. Despite their high accuracy and precision, spectroscopy and chromatography have some disadvantages to consider, such as the relatively costly equipment, the use of toxic organic compounds (solvents) that generate large quantities of waste.…”

“…Many researchers made efforts to identify methylxanthine derivates such as XT, TP, and TB [1,3,5,7,8]. To the best of our knowledge, concerning the simultaneous electrochemical determination of these three biomolecules, there is only one publication in the literature.…”