The effects of organic modifier on physicochemical and chromatographic characteristics of self‐assembled micelle from poly (stearyl methacrylate‐co‐methacrylic acid) in electrokinetic chromatography

Abstract

In our previous work, organic solvents, especially 1-butanol, play a key role to separate highly hydrophobic analytes in EKC using the polymeric micelle self-assembled from amphiphilic random copolymer poly (stearyl methacrylate-co-methyl acrylic acid) (P(SMA-co-MAA)) as a novel pseudostationary phase. Herein, the influences of organic solvents on polymeric micelle physicochemical properties including environmental micropolarity and dimension, as well as chromatographic characteristics containing elution window, hydrophobic selectivity and polar group selectivity were investigated in detail. P(SMA-co-MAA) has extremely low CMC of 1.26 × 10(-6) g/mL, and the self-assembled micelles with selective solvent method had regular spherical structure with diameter about 50 nm. The experimental results showed that methanol, isopropanol or acetonitrile molecules could not penetrate into the interior of the polymeric micelles, and mainly affected the properties of surrounding running buffer. Too much these organic solvents led to elution window narrowed down, methylene selectivity and group selectivity weaken, even the micelles collasped. Whereas, addition of 2% 1-butanol did not influence the elution window, instead, improved the hydrophobic selectivity. Furthermore, both better group selectivity and faster migration for relatively hydrophobic analytes could be achieved simultaneously. It indicated that 1-butanol could insert into the polymeric micelle and 2% 1-butanol was enough to modify the structure of the micelles.

Comparison of a polymeric pseudostationary phase in EKC with ODS stationary phase in RP‐HPLC

“…Thus, it would be interesting in comparison of selectivity between the polymeric PSP and ODS SP which is widely used in RP‐HPLC. In another work of ours , the influences of organic solvents on P(SMA‐ co ‐MAA) polymeric micelle physicochemical properties and chromatographic characteristics were investigated. But the further study on selectivity of the polymeric micelle modified with or without organic solvents was still required.…”