RAFT polymerized nanoparticles: Influences of shell and core chemistries on performance for electrokinetic chromatography

Abstract

The performance and solvation characteristics of two novel latex nanoparticle (NP) pseudo-stationary phases (PSPs) for EKC are determined and compared to those of previously reported micellar, polymeric, and NP materials. The new NPs have shells composed of strongly acidic poly(AMPS) as opposed to the poly(acrylic acid) shell of the prior NP, and have varied hydrophobic core chemistry of either poly(butyl acrylate) or poly(ethyl acrylate). The NPs poly(AMPS) shell shows only minor changes in mobility and selectivity between pH 4.9 and 9.4, allowing adjustment of pH to influence and optimize separation performance. All of the NP phases have significantly different solvation characteristics and selectivity relative to SDS micelles. The selectivity and solvent character are similar for NPs with poly(butyl acrylate) cores and different shells, but vary significantly between NPs with poly(butyl acrylate) versus poly(ethyl acrylate) cores. NPs with poly(butyl acrylate) cores are among the least cohesive PSPs reported to date, while the NP with poly(ethyl acrylate) core is among the most cohesive. The results demonstrate that PSPs with unique selectivity can be generated by altering the chemistry of the hydrophobic core.

Performance and selectivity of cationic nanoparticle pseudo‐stationary phases in electrokinetic chromatography

“…The performance of each cationic latex nanoparticle was evaluated by analyzing the retention of six alkyl phenyl ketones; the results are shown in Table . The electrophoretic mobility, μ np , was consistently less than those seen for SDS and anionic latex nanoparticles . Two‐sample t ‐tests assuming unequal variances were used to assess reproducibility and look for differences in methylene selectivity between nanoparticles with different shell or core chemistries.…”

“…The combined LSER coefficients for each core were compared to literature values of other latex nanoparticles, three cationic surfactants with different headgroups, and SDS . The v term of the cationic latex nanoparticles was comparable to cationic surfactants, and larger than the anionic latex nanoparticles.…”

“…For each nanoparticle studied μ eo , μ np , the methylene selectivity ( α CH2 ), the migration window ( t 0 / t np ), and the average number of theoretical plates ( N ) for the six ketones was calculated. An LSER analysis was performed by measuring and fitting the retention factors of 39 different solutes that had been used in previous LSER studies to the LSER model . Retention factors are calculated with the following equation: where μ eo is the electroosmotic mobility of the system determined by the migration time of acetone, μ sol is the total (observed) mobility of the solute, and μ np is the electrophoretic mobility of the nanoparticle determined as described above.…”

“…RAFT is compatible with a variety of monomers, making it possible to synthesize a wide variety of polymers . Latex nanoparticles synthesized by RAFT have been shown to perform well as a PSP and be compatible with both UV and MS detection .…”

Phospholipid bilayer affinities and solvation characteristics by electrokinetic chromatography with a nanodisc pseudostationary phase

“…, who generated values through combination of atomic physiochemical properties. LSER characterization was performed using 32 LSER probe solutes similar to the list used in a recent study of a latex nanoparticle PSP . After measurement of k ‐values, Excel was used for multivariate linear regression to determine LSER coefficients.…”