Influence of Stationary Phase Capacity on Anionic Separation: A Comparative Study of Dionex IONPAC AS 23 and AS11 Columns

Abstract

Ion chromatography is a known laboratory technique used for separation and quantification of inorganic anions in food, environmental, pharmaceutical and industrial products. Ion- exchange chromatography works on the basis of ion-exchange principle of stationary phase which is a key factor in retention time, selectivity and resolution of an analyte. The main objective of the current research is to evaluate the effect of stationary phase capacity on ionic separation through comparative analysis of the Dionex Ion Pac AS11 and Dionex Ion Pac AS23 columns with use of suppressed conductivity detection. Major inorganic anions such as fluorides, chlorides, nitrites, nitrates, phosphates and sulfates were detected in standard solutions and in cases of real environmental waters and milk at optimized chromatographic conditions. The performance evaluation of the two types of columns was based on the results of investigations for retention period, peak resolution, selectivity, linearity, precision, accuracy as well as limits of detection (LOD) and quantification (LOQ). The findings showed that the Ion Pac AS11 column has a better ability to differentiate and slightly retain highly retained and multivalent anions during gradient elution. Therefore, the use of the Ion Pac AS11 column is align with analyzing complicated environmental samples. On the other hand, the Ion Pac AS23 column is characterized by shorter analysis time, stable baseline performance, and excellent resolution of easily soluble inorganic anions during isocratic elution, which suits it for everyday water quality testing. Validation of the method showed that it works well, with good linearity, precision, accuracy, recovery, sensitivity, and reproducibility. These results emphasize the importance of choosing the right stationary phase depending on the complexity of the sample and objectives of analysis. This study brings practical advice on improving ion chromatographic processes in laboratories aimed to analyze different inorganic anions.