Application of Ion Chromatography for Determination of Inorganic Ions and Sorbitol in Phosphate Syrup

In this study, ion chromatography (IC) methods were developed and validated for the determination of sodium, potassium, phosphate, and sorbitol in phosphate syrup. For the analysis of cations, an IonPac CS16 column was utilized, with a mobile phase of 50 mM methanesulfonic acid and a flow rate of 0.5 mL/min. For the analysis of phosphate and sorbitol, an IonPac AS19 column was employed, using a flow rate of 1.0 mL/min and mobile phases of 50 and 20 mM NaOH, respectively. In the validation tests, sensitivity was assessed on the basis of the signal-to-noise ratio, with the limit of detection for all analytes being below 0.001 mM. The linearity curves for all analytes exhibited determination coefficients greater than 0.999, indicating excellent linearity. The relative standard deviation (RSD%) for both inter-day and intra-day precision was not more than 1%. Accuracy, expressed as recovery (%), ranged from 98% to 101% for all ions. The validation of these methods demonstrated their reliability for the measurement of these four analytes. Furthermore, the stability of the syrup was evaluated over 6 months at room temperature (25°C). The results indicated that the phosphate syrup remained stable under these conditions, with the analyte contents staying close to 100%.