A facile colorimetric method for highly sensitive ascorbic acid detection by using CoOOH nanosheets

In this work, based on a fast redox reaction between CoOOH nanosheets and AA, a very simple and highly sensitive colorimetric assay was developed to detect AA in buffer and real samples. In the detection system, CoOOH nanosheets exhibit a strong ultraviolet-visible (UV-vis) absorption peak at around 430 nm with an observable yellowish-brown color. The presence of AA reduces the CoOOH nanosheets to Co2+ ions and subsequently weakens the color of the solution, which results in a dramatic decrease of the absorption signal. The assay showed a good linear range from 0.25 M to 60 M with a detection limit of 57 nM for AA. Meanwhile, the detection system also exhibited high selectivity against other electrolytes and biomolecules. More importantly, this procedure is very simple, and the entire procedure can be finished within 15 min. This method has also been successfully applied to the detection of AA in vitamin C tablets and beverages with reliable results.