Selective detection of uric acid in the presence of ascorbic acid based on electrochemiluminescence quenching

The direct detection of uric acid (UA) using electrochemical method is usually significantly interfered by the presence of other electroactive species such as ascorbic acid (AA) in biological samples. Here, we describe a new method of UA determination based on the quenching of the electrochemiluminescence (ECL). It was found that the emission of the Ru(bpy)32+ (bpy = 2,2′-bipyridine)/tri-n-propylamine (TPrA) system could be influenced much more significantly by UA than by AA, particularly when the ECL was produced via the low-oxidation-potential (LOP) route. In the presence of 10 mM TPrA, the Stern–Volmer constant (KSV) of the LOP ECL quenching could be as high as 9.1 × 104 M−1 for UA, while the influence of AA on the LOP ECL signal was not obvious. Other possible interfering biological species, such as cysteine, oxalate, purine, glucose, and urea, exhibited much less influence on the LOP ECL as compared with UA. The unique quenching effects led to sensitive and selective detection of UA in human urine samples.