Abstract: According to the respective features of the ratio spectra of the guanosine 5’-monophosphate(5’-UMP), inosine 5’-monophosphate(5’-IMP) and uridine 5’-monophosphate(5’-UMP) and taking 5’-UMP as disturbance component, 258, 285, 244 and 280 nm were chosen as the determining wavelengths of the 5’-GMP and 5’-IMP. Taking the 5’-IMP as disturbance component, 211 and 241 nm were chosen as the determining wavelengths of the 5’-UMP. It showed that for the three components good linear correlationships exit as 5’-GMP(0.15～5 mg/100 ml), 5’-IMP(0.2～6 mg/100 ml), 5’-UMP (0.25～4 mg/ 100 ml). The average recoveries are 100.2%, 100.2% and 99.5% respectively. The method is simple and practical with fewer determination wavelengths and powerful spectral resolution and can be performed on a lower level instrument. It is easy to generalize application.

Key words: dual-wavelength ratio spectrometry； guanosine 5&rsquo, -monophosphate(G)； inosine 5&rsquo, -monophosphate(I)； uridine 5&rsquo, -monophosphate(U)；