Abstract
An original voltammetric sensor (Au-gr/CVE) based on a carbon veil (CV) and phytosynthesized gold nanoparticles (Au-gr) was developed for ascorbic acid (AA) determination. Extract from strawberry leaves was used as source of antioxidants (reducers) for Au-gr phytosynthesis. The sensor was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy and electrochemical methods. Optimal parameters of AA determination were chosen. The sensor exhibits a linear response to AA in a wide concentration range (1 μM–5.75 mM) and a limit of detection of 0.05 μM. The developed sensor demonstrated a high intra-day repeatability of 1 μM AA response (RSD = 1.4%) and its stability during six weeks, selectivity of AA determination toward glucose, sucrose, fructose, citric, tartaric and malic acids. The proposed sensor based on Au-gr provides a higher sensitivity and a lower limit of AA detection in comparison with the sensor based on gold nanoparticles synthesized by the Turkevich method. The sensor was successfully applied for the determination of AA content in fruit juices without samples preparation. The recovery of 99%–111% and RSD no more than 6.8% confirm the good reproducibility of the juice analysis results. A good agreement with the potentiometric titration data was obtained. A correlation (r = 0.9867) between the results of AA determination obtained on the developed sensor and integral antioxidant activity of fruit juices was observed.
Highlights
L-ascorbic acid (AA) is a water-soluble vitamin with powerful antioxidant properties, which is actively involved in the biochemical processes of the human body
The aims of this research were (i) to study the relationship between electrochemical and morphological properties of electrodes modified with gold nanoparticles obtained by phytosynthesis using extracts from strawberry leaves, (ii) creation of a voltammetric sensor based on a carbon veil and gold nanoparticles obtained by green synthesis, and (iii) algorithm development for AA determination with the use of a new sensor
A new sensor based on a carbon veil, modified with “green” gold nanoparticles is described
Summary
L-ascorbic acid (AA) (vitamin C) is a water-soluble vitamin with powerful antioxidant properties, which is actively involved in the biochemical processes of the human body. Unlike plants and most animals that have the ability to synthesize AA from glucose, the human body can receive the required amount of AA only from external sources. The physiological level of AA in the body is ensured by its intake only from outside (the use of foods rich in vitamin C, various food additives and pharmaceuticals). It is added to certain foods and drinks to give them antioxidant properties and to prevent color and taste changes. Taking into consideration the nutritional value and therapeutic AA properties, monitoring of AA content should be recognized as an important and relevant task for assessing the quality of finished food products, raw materials and a number of other substances
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