Quick and CostEffective Estimation of Vitamin C in Multifruit Juices using Voltammetric Methods Ascorbic Acid (AA) is a natural and powerful watersoluble antioxidant associated with longlasting food products. As time passes, the AA content in products sharply decreases, and they become increasingly degraded. There are several techniques to precisely quantify AA concentrations. However, most of them employ costly laboratory instruments, such as HighPerformance Liquid Chromatography (HPLC) or complex electrochemical methods, which make unfeasible recurrent AA measurements along the entire supply chain. To address this issue, we contribute with an infield and realtime voltammetric method, carried out with a lowcost, easytouse, and portable device. An unmodified ScreenPrinted Electrode (SPE) is used together with the device to achieve short reading times. Our method has been extensively tested in two multifruit juices using three different SPEs. Calibration curves and Limit of Detection were derived for each SPE. Furthermore, periodic experiments were conducted to study the shelf life of juices under consideration. During the analysis, a set of assays for each SPE were implemented to determine the remaining AA amount per juice and compare it with that obtained using HPLC under the same conditions. Results revealed that our costeffective device is fully comparable to the HPLC equipment, as long as the juice does not include certain interferents; a scenario also contemplated in this article.

Voltammetry at HexamethylPTerphenyl Poly(Benzimidazolium) (HMTPMBI)Coated Glassy Carbon Electrodes: Charge Transport Properties and Detection of Uric and Ascorbic Acid We describe the voltammetric behavior of an anionexchange membrane, hexamethylpterphenyl poly(benzimidazolium) (HMTPMBI). The anionexchange properties of HMTPMBI chemically modified electrodes were investigated using K4Fe(CN)6 and K2IrCl6 as redox probes. The permselectivity properties of HMTPMBI chemically modified electrodes were ascertained using tris(22xe2x80x99)bipyridylruthenium(II) chloride Ru(bpy)32. Cyclic voltammetry and chronoamperometry were utilized to extract parameters such as the concentration of the redox mediators inside the films and the apparent diffusion coefficients. We found the concentration of K4Fe(CN)6 and K2IrCl6 redox species within HMTPMBIcoated films to be on the order of 0.04xe2x80x930.1 molxc2xb7dmxe2x88x923, and values of Dapp ca. 10xe2x88x9210xe2x80x9310xe2x88x929 cm2xc2xb7sxe2x88x921. To evaluate the possibility of using such a polymer coating in electroanalysis, HMTPMBImodified electrodes were utilized for the voltammetric detection of uric acid in artificial urine, Surinexc2xae and ascorbic acid in Vitamin C samples. The results showed that HMTPMBIcoated electrodes can detect uric acid in Surinexc2xae with a limit of detection (LoD) of 7.7 xc2xb5M, sensitivity of 0.14 xc2xb5Axc2xb7xc2xb5Mxe2x88x921xc2xb7cmxe2x88x922, and linear range between 5 xcexbcM and 200 xcexbcM, whereas for Vitamin C tablets, the LoD is 41.4 xc2xb5M, the sensitivity is 0.08 xc2xb5Axc2xb7xc2xb5Mxe2x88x921xc2xb7cmxe2x88x922, and the linear range is between 25 xcexbcM and 450 xcexbcM.