Abstract: A rapid, sensitive real-time method for the detection of guanine in fish flesh was developed by impurity removal using microporous resin adsorption combined with surface-enhanced Raman spectroscopy (SERS). The percentage adsorption of protein onto a column packed with D152 resin (20?cm × 1?cm, i.d.) was 83%–92% and the recovery of guanine was higher than 95%. Using one-factor-at-a-time and orthogonal array design methods, the optimum adsorption and desorption conditions were established as follows: sample loading flow rate 3 mL/min, eluent pH 4.0, and elution flow rate 0.5?mL/min. Silver-coated gold nanoparticles (Au@Ag NPs) were used as a substrate for SERS. Guanine concentration in the range from 0.001 to 100?mg/L had a linear relationship with its Raman intensity, with a correlation coefficient (R2) of 0.969 9 and the detection limit of the method was 0.1?mg/L. The entire detection process took only 10 minutes without the requirement for any complicated sample preparation. These results show that the chromatographic column filled with D152 resin could effectively eliminate the interference of impurities such as proteins in fish flesh, and the SERS method could rapidly and sensitively detect trace purines in fish flesh with a detection limit lower than that of the existing HPLC method.

Key words: macroporous resin; guanine; surface-enhanced Raman spectroscopy; rapid detection