Ag+-3,3 ',5,5 '-tetramethylbenzidine as a probe for colorimetric detection of ascorbic acid in beverages

摘要

A novel and sensitive method for ascorbic acid (AA) determination utilizing Ag+-3,3 ',5,5 '-tetramethylbenzidine (TMB) as a colorimetric probe was proposed. In a weak acidic medium, Ag+ could oxidize TMB to oxidized TMB (ox-TMB) and cause a blue color solution with an absorption peak centered at 652 nm. However, the addition of AA could induce the reduction of ox-TMB, leading to shallower blueness and lower absorbance. Under the selected experimental conditions, there was a good linear relationship between the decrease of absorbance (Delta A) and AA concentration in the range of 0.5-60 mu M, and the detection limit was as low as 0.23 mu M. The feasibility of this method was verified in commercial beverages with recoveries of 95.8-104.1%. The method has the advantages of simplicity and practicability. More importantly, no nanomaterials need to be prepared.