Abstract: A new method was established for the simultaneous determination of two 5O`- mononucleotides (guanosine monophosphate, GMP; inosine monophosphate, IMP) within one run in soy sauce by high performance capillary electrophoresis. The analysis was performed using an uncoated capillary (50 μm i.d, total length 60.2 cm, and effective length 50 cm). The running buffer was composed of 30 mmol/L Na2B4O7, 30 mmol/L Na2CO3 and 60 mmol/L hydroxypropyl-beta cyclodextrins. The sample medium was 50 mmol/L acetic acid. The detection wavelength was 254 nm. A good linear relationship between the corrected peak area and concentration in the range of 5-100 mg/L were obtained for GMP and IMP with correlation coefficients (r) of 0.9998 and 0.9997, respectively. For both GMP and IMP, the limit of detection (LODs) was 2 mg/L, and the limit of quantification (LOQs) was 5 mg/L. Totally 9 soy sauces commercialized in Beijing were analyzed, and the results were in good agreement with those obtained by high performance liquid chromatography.

Key words: high performance capillary electrophoresis, nucleotides, guanosine 5O`- monophosphate, inosine 5O`- monophosphate, soy sauce