Development of a high-performance liquid chromatography method for analyzing disodium 5'-guanylate and disodium 5'-inosinate levels in flavor enhancers

Objective: This study aimed to develop a selective analytical method for assessing disodium 5'-guanylate and disodium 5'-inosinate levels in flavor enhancers. Methods: The levels were assessed using high-performance liquid chromatography (HPLC) with a photodiode array detector (PDA) (wavelength =255 nm) and a SunFire® C18 column (250 mm × 4.6 mm × 5 µm). The mobile phase comprised a mixture of potassium phosphate buffer and an ion pair reagent-hexane-1-sulfonic acid sodium salt - with a flow rate of 1.2 mL/min. The ion pair was used to generate a neutral equilibrium, which resulted in increased retention of the analytes. Optimized analysis conditions were then validated regarding accuracy, precision, linearity, selectivity, and the limits of detection and quantification. Results: The average levels of disodium 5'-inosinate in the six analyzed samples were 0.24±1.46, 0.21±2.69, 0.58±3.26, 0.21±0.84, 0.22±3.59, and 0.47±2.21%, respectively. Regarding disodium 5'-guanylate, the average levels were 0.15±2.85, 0.15±0.12, 0.41±3.80, 0.16±1.72, 0.27±1.18, and 0.34±1.83, respectively. Conclusion: The optimal conditions for analyzing disodium 5'-guanylate and disodium 5'-inosinateusing HPLC with a PDA and SunFire C18 column were λ=255 nm, a mobile phase of potassium phosphate buffer and sodium hexane sulfonate, and a flow rate of 1.2 mL/min. For disodium 5'-inosinate, its average levels in samples A-F were 0.24±1.46, 0.21±2.69, 0.58±3.26, 0.21±0.84, 0.22±3.59, and 0.47±2.21%, respectively. Meanwhile, the average levels of disodium 5'-guanylate in the samples were 0.15±2.85, 0.15±0.12, 0.41±3.80, 0.16±1.72, 0.27±1.18, and 0.34±1.83%, respectively.