Author(s):
1. Darija Knežević Ratković, Medicinski fakultet Banja Luka , Republic of Srpska, Bosnia and Herzegovina
2. Irena Kasagić-Vujanović, Republic of Srpska, Bosnia and Herzegovina

Abstract:
Hydrophilic interaction liquid chromatography (HILIC) is used for analyzing small polar molecules, especially in pharmaceutical field sciences. Retention mechanisms in HILIC are complex, with interactions between the surface of the stationary phase and analytes in the mobile phase being crucial for separation. The retention mechanism varies with different mobile and stationary phase pairs and depends on the type and ionic state of analytes. Therefore, this paper aimed to evaluate the contribution of anion-exchange and cation-exchange retention mechanisms to the overall retention of amitriptyline hydrochloride and its impurities denoted as A, B, C, D, F, and G on amino and silica stationary phases in HILIC, respectively. High R2 values (> 0.995) indicate a significant cation exchange contribution to the retention of charged analytes in the silica stationary phase (non-ionized analytes – impurities A and G, did not exhibit ion-exchange retention). Basic analytes show longer retention at lower buffer ionic strength due to reduced competition with buffer ions. Higher pH increases retention of charged analytes by ionizing the surface of the silica stationary phase, especially for highly hydrophilic analytes like impurity F. On the other hand, higher buffer ionic strength promotes the retention of basic analytes on the amino stationary phase due to reduced electrostatic repulsion between the analytes and the surface of the stationary phase. However, R2 values point to cation exchange contributing more to overall retention in the silica stationary phase than anion exchange in the amino stationary phase.

Key words:
cation-exchange, anion-exchange, retention mechanisms, hydrophilic interaction liquid chromatography, amitriptyline

Thematic field:
SYMPOSIUM C - Water

Date of abstract submission:
26.07.2024.

Conference:
Contemporary Materials 2024 - Savremeni Materijali

Applied paper from author