Evaluation of the Base Stability of Hydrophilic Interaction Chromatography Columns Packed with Silica or Ethylene-Bridged Hybrid Particles

Abstract

Stability as a function of mobile phase pH is an important consideration when selecting a chromatographic column. While the pH stability of reversed-phase columns is widely studied, there are relatively few reports of the stability of hydrophilic interaction chromatography (HILIC) columns. We evaluated the stability of silica and ethylene-bridged hybrid HILIC columns when used with mobile phases containing basic buffers. The predominant mode of column degradation observed in our studies was a decrease in efficiency due to voiding, resulting from the hydrolysis of the silica particles. Associated with this were increases in tailing factors. Retention factor changes were also noted but were smaller than the efficiency losses. The dependence of the rate of efficiency decrease on the key variables of temperature, mobile phase pH and water content were studied for an unbonded silica column. The effect of the acetonitrile concentration on the pH of the mixed aqueous/acetonitrile mobile phases was also investigated. Using conditions found to cause a 50% decrease in efficiency after approximately five hours of exposure to the basic solution, we evaluated eight different commercially available HILIC columns containing silica or ethylene-bridged hybrid particles. The results show large differences between the stability of the silica and ethylene-bridged hybrid particle stationary phases, with the latter exhibiting greater stability.

Optimization of chromatographic buffer conditions for the simultaneous analysis of phosphatidylinositol and phosphatidylinositol phosphate species in canola

“…This development process saw the elimination of buffer from mobile phase B, which was highly organic and poorly solubilized the polar ammonium bicarbonate crystals. Not only did this further reduce the risk of buffer precipitation, but it comparatively increased the elution strength of mobile phase B, reducing the likelihood of exceptionally hydrophobic species carrying over between injections, and prevented the mobile phase from increasing in alkalinity with organic composition, which could potentially exceed the columns limit [36]. The final conditions are provided in section 2.3.…”

“…The precision for peak area measurements remained high from between 5 and 500 ppb, though rapidly declined over measurements less than 1 ppb in concentration. The LOD values provided in the mobile phase from increasing in alkalinity with organic composition, which could potentially exceed the columns limit [36]. The final conditions are provided in section 2.3.…”