Method study on determination of total purine content in fish meat by diazotization reaction combined with SERS

A new analytical method was developed to determine total purine content in fish meat. The analysis principle is that total purine extracted from fish meat are turned into uric acid by diazotization reaction and xanthine oxidase reaction. Then, the content of uric acid is measured by surface-enhanced Raman spectroscopy (SERS). The results showed that the optimal conditions for the diazotization reaction were at 60 °C for 40 min, using 0.16 M HCl, and 3.00 g/L NaNO2. The optimal xanthine oxidase reaction conditions were using 100 U/L xanthine oxidase, conducting at 30 °C and pH 7.0 for 40 min. The calibration curve established at the characteristic Raman peak of 631 cm−1 had a good linear relationship (R2 = 0.9864). The recovery rate was between 101.7% and 105.0%. Therefore, the total purine content in the fish meat can be quantitatively determined with this new method. •The sensitive detection of total purine by diazotization and SERS was developed.•The four purines were totally turned into uric acid by diazotization reaction.•The uric acid was measured by SERS using Au@Ag NPs as active substrate.•The result of developed method showed nearly identical to the HPLC.