Sensitive and facile colorimetric sensing strategy for ascorbic acid determination based on CoOOH nanoflakes-ABTs oxidative system

Ascorbic acid (AA) is one of the most important vitamins and serves many physiological activities in the body. In this work, we propose a simple colorimetric sensor for the rapid detection of AA through the redox reaction between CoOOH nanoflakes and ascorbic acid with the 2, 2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) as a colorimetric signal indicator. CoOOH nanoflakes could catalytically oxidize colorless ABTS to produce green oxidized ABTS (ox ABTS) with an absorption band at 412 nm in UV-vis spectra. The presence of AA could induce the oxidation of ABTS, resulting in a significant color fading and decrease of the absorbance at 412 nm. Thus quantitative detection of AA is realized. Under the optimal experimental conditions, the linear range is obtained from 0.5 to 15 mu M with a lower detection limit of 0.16 mu M (S/N = 3). Particularly, this colorimetric assay is capable of detecting AA in different vitamins C tablet and fresh kiwi fruit samples. Hence, the fast response, high sensitivity and easy operation of the proposed colorimetric sensor make it suitable for further application in bioassay.