Abstract:

An ion exclusion chromatography method was established for the simultaneous determination of glycerol， acetic acid and sodium bisulfite in compound amino acid injection （14AA）. No tedious sample pretreatment is required； the sample can be directly injected after filtration through a 0.22 μm membrane filter. Chromatographic separation was achieved using an Xtimate Sugar-H column （300 mm×7.8 mm， 5 μm） packed with a strong ion-exchange resin based on a rigid styrene/divinylbenzene matrix， which is specially designed for the separation of sugar alcohols and organic acids via the ion-exclusion mechanism. The mobile phase was 7.5 mmol/L sulfuric acid solution， which was selected as it can suppress the ionization of target analytes and enhance their retention on the stationary phase； the amino groups of amino acid components undergo strong ionization， leading to no retention. Isocratic elution was adopted to ensure stable separation efficiency and short analysis time， with the flow rate set at 0.5 mL/min. Based on the ultraviolet absorption characteristics of the target analytes， 200 nm was selected as the detection wavelength. The column temperature was set at 65 ℃ and the injection volume was optimized to 10 μL， which ensures the detection sensitivity while avoiding column overload. The external standard method was adopted for quantitative analysis， featuring simple operation and reliable results. The method exhibited excellent specificity： blank solvent and negative matrix solution tests verified that amino acids caused no interference with the determination of target analytes， and the target analytes achieved good resolution from adjacent peaks. For the linearity investigation， standard solutions were prepared with linear ranges set as follows： 1.197–59.87 mg/mL for glycerol， 0.036 08–1.804 mg/mL for acetic acid， and 0.000 791 6–0.633 3 mg/mL for sulfite. Within these mass concentration ranges， the linear correlation coefficients （r） of all components were greater than 0.999 5， indicating an excellent linear relationship of the method. The accuracy was verified by spiked recovery tests at three levels （80%， 100% and 120% of the labeled amount）， with three parallel preparations for each level. The results showed that the average recoveries of the target analytes ranged from 99.21% to 102.6%， with relative standard deviations （RSDs） of 0.09% to 0.86% （n=3）， demonstrating the high accuracy of this method. The ion exclusion chromatography method established in this study can effectively eliminate the interference of the amino acid matrix in compound amino acid injection （14AA）， and has the advantages of rapid analysis， simple operation， strong specificity and high accuracy， making it suitable for the routine quality control of glycerol， acetic acid and sodium bisulfite in this preparation. This method provides a reliable analytical and testing tool for the quality assurance and safety control of compound amino acid injection （14AA） during production and storage.

Key words: ion exclusion chromatography, compound amino acid injection （14AA）, glycerol, acetic acid, sodium bisulfite