Application of cyclic voltammetry to analyse uric acid and reducing agents in commercial milks.

Cyclic voltammetry (CV) and high performance liquid chromatography (HPLC), were compared to quantify uric acid and antioxidant reducing agents in 36 milk samples. The enzymes uricase and ascorbate oxidase were used to remove uric and ascorbic acids and showed that the peaks obtained by CV and HPLC did not contain contributions from other unknown compounds. The levels of uric acid obtained by CV compared well to those determined using HPLC, with only a few exceptions, and the average difference was around 6%. CV measurements were made using the main anodic peak seen at approximately 330 mV (Ag/AgCl), while a later oxidation peak at approximately 650 mV can be associated with further reducing agents present in milk. The electrochemical method was quicker to apply than HPLC that included a pre-treatment step, and provides an inexpensive and simple method for the reliable analysis of uric acid in milk.