Sensitive and selective determination of vitamin B2 in non-alcoholic beverage and milk samples at poly (glutamic acid)/zinc oxide nanoparticles modified carbon paste electrode

Abstract

Background The deficiency of vitamin B2 can lead to many health problems. Therefore, it is necessary to develop a sensitive, selective and fast method for the determination of vitamin B2 in food samples. In this work, a sensitive, selective and low-cost electrochemical sensor was developed using poly (glutamic acid) and Zinc oxide nanoparticles (ZnO NPs) for vitamin B2 in non-alcoholic beverage and milk samples. Methods The modification of the electrode surface was carried out by electropolymerization of glutamic acid on ZnO NPs–carbon paste electrode (ZnO NPS–CPE). The prepared electrodes were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X-Ray diffraction (XRD). CV and square wave voltammetry (SWV) were used to investigate the electrochemical behavior of vitamin B2 at the modified electrode. The effect of various parameters such as amount of ZnO NPs, polymerization cycle, concentration of the monomer, pH, scan rate and accumulation time were optimized to obtain maximum sensitivity at the modified electrode. Results The developed sensor showed high electrocatalytic activity towards vitamin B2. Under the optimized conditions, the developed sensor showed a linear response in the range 0.005–10 µM with a low detection limit of (LOD) 0.0007 ± 0.00001 µM and high sensitivity of 21.53 µA/µM. Conclusions A reproducible, repeatable, stable and selective sensor was successfully applied for the quantification of vitamin B2 in beverage and milk samples with acceptable recoveries in the range of 88–101%.

Sensitive determination of diuron on zinc oxide nanoparticles modified carbon paste electrode in soil and water samples

“…This relatively high size value could be explained by the fact that ZnONPs particles appeared as agglomerates. This result, in agreement with literature [29] is due to its large surface area and high surface energy. Similar works were reported by Keerthi et al [36] and Chikere et al [39], in which zinc oxide nanoparticles appeared as agglomerates due to their surface effects.…”

“…In this way, enhanced response was noticed before the saturation point, beyond which the adverse effect (decrease) occurs. Literature review state reports in this way, therefore strengthening our results [29, 34, 50]. Then, the amount of ZnONPs at 5 % was chosen in future measurements.…”

“…Therefore, the presence of ZnONPs in the CPE constitution has led to an enhanced electron transfer rate at the electrode surface resulting in a likely increase in the conductivity and area of the ZnONPs-CPE [34,41]. Besides, ZnONPs have an affinity with [Fe-(CN) 6 ] 3À /4À which would have induced the catalysis of the redox reaction of [Fe(CN) 6 ] 3À /4 [29,41]. Moreover, an increase in the redox peaks current intensities occurs on the surface of ZnONPs-CPE, in comparison to CPE, being this behavior related to the high conductivity and area of the ZnONPs-CPE induced by ZnONPs [39,41].…”

“…Meanwhile, electrochemical methods based on sensors and biosensors stand as excellent alternative for monitoring diuron in the environment. Indeed, electrochemical methods offer desired selectivity, sensitivity, low production cost and portability for field analysis [2,[27][28][29][30][31][32]. Previous works indicate the use of chemical modifiers to improve the sensitivity and selectivity of electrochemical sensors.…”

“…However, we are increasingly witnessing the wide use of the so-called emerging modifiers such as carbon nanoparticles, carbon nanotubes and metal oxide nanoparticles. Thus, zinc oxide nanoparticles (ZnONPs), a transparent metal oxide semiconductor, is used in many fields, including the design of sensors for the detection of gases, humidity in the atmosphere and food coloring [29,33,34]. In addition, ZnONPs have been explored as diuron degradation catalyst and the results showed good degradation of diuron without formation of toxic intermediates [35].…”