Three versus five micrometer chlorinated polysaccharide‐based packings in chiral capillary electrochromatography: efficiency and precision evaluation

Abstract

In an earlier part of this study (performance evaluation) it was observed, for home-made capillary electrochromatography (CEC) columns, that smaller particle diameters do not always generate higher efficiencies. This phenomenon was further examined in this study, evaluating Van Deemter curves. Naphthalene and trans-stilbene oxide were analyzed on four 3 µm and four 5 µm chlorinated polysaccharide-based chiral stationary phases (CSPs) applying voltages ranging from 5 to 30 kV. Neither the 3 nor the 5 µm packings generated systematically the highest efficiencies. The varying column efficiencies were optimized by evaluating nine packing procedures for both 3 and 5 µm CSPs. Again it was observed that smaller particle-size packings were not necessarily beneficial for the efficiency of the CEC analysis. This observation was statistically evaluated. A variability study evaluated different precision estimates related to column packing and replicate measurement conditions. The best columns with the highest efficiencies (for chiral separations) and good precision, that is, the lowest RSD values, were generated by the packing procedure in which an MeOH-slurry and a water rinsing step of 8 h were applied.

Enantiomers separation by capillary electrochromatography using polysaccharide‐based stationary phases

“…Even though a loss in the efficiency was observed when the particle diameter was enlarged in the range of 5–7 μm , only a slight difference was observed when 3 and 5 μm particles were compared, as also reported in the conclusions by Hendrickx et al. . However, as expected, the EOF was strongly diminished when using 12 μm particles.…”

“…However, as expected, the EOF was strongly diminished when using 12 μm particles. In addition, as the same authors have described in their investigations , the capillary column packing procedure probably strongly influence chromatographic chiral separation. Indeed, between eight packing procedures of amylose tris(5‐chloro‐2‐methylphenylcarbamate) based CSP, the slurry method with MeOH followed by a rinse with water for 8 h allowed to produce high‐efficiency and precision capillary columns.…”

“…Vander Heyden and his research group have developed separation strategies based on the large‐scale screening of racemic mixtures generally in pharmaceutical products using polysaccharide derivatives based CSPs . In this regard, basic, neutral, and bifunctional pharmaceutical compounds were selected and tested in order to verify the enantiorecognition capabilities of chlorinated and nonchlorinated CSPs, being the firsts superior to the seconds.…”

“…In this way, their contribution in the Van Deemter's equation would be reduced resulting in high chromatographic efficiency. However, when these small particles are employed for chiral separation on polysaccharide‐based CSPs, the effect was not so clear .…”

“…In this regard, well‐known authors in the chromatography field, such as Chankvetadze , Blaschke , Fanali , Mangelings , Vander Heyden , and their research groups, have contributed to the study in CEC of CSPs based on amylose or cellulose derivatives absorbed as coating or chemically immobilized on silica‐based material.…”