Retention behavior and selectivity of a latex nanoparticle pseudostationary phase for electrokinetic chromatography

Abstract

The retention characteristics and separation selectivity of a novel latex nanoparticle (NP) pseudostationary phase (PSP) for electrokinetic chromatography have been characterized. The anionic NPs have very low or no affinity for cationic solutes, but show significant interactions and retention based on hydrophobic interactions. Retention factors of alkyl-phenyl ketones increase linearly with the concentration of the NPs and have zero or near zero y-intercepts as expected for electrokinetic chromatography with non-micellar PSPs. The retention factors of these solutes and representative pharmaceuticals decrease logarithmically with increases in the concentration of ACN in the background electrolyte, as expected for reversed-phase retention. Linear solvation energy relationship analysis indicates that the NPs are less cohesive than would be expected for polymeric PSPs with similar structure but that the overall separation selectivity can be expected to be similar to polymer PSPs with similar backbone chemistry. The results indicate that the hydrophobic core of the NPs is non-cohesive and is highly accessible to solutes, whereas the ionic head groups are not as accessible and do not contribute substantially to retention or selectivity.

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

“…The results of the LSER analysis for EAAMPS NP, BAAMPS NP, BAAA NP , two polymeric PSPs and SDS micelles are presented in Table . As has been previously observed in many EKC studies, the v and b terms, representing PSP cohesivity and acidity respectively, are the largest and most important terms for each PSP.…”

“…Linear solvation energy relationships (LSER) characterization was performed in 10 mM Tris buffer at a pH of 7.21 with a NP concentration of 0.30%. The 33 LSER compounds and descriptors used in this study are similar to the LSER compounds used for previous studies of NP PSPs as listed in the supporting information. Compounds were chosen in order to cover the appropriate range of sizes and solute properties.…”

“…Recent work utilizing latex NP PSPs consisting of amphiphilic A‐B block copolymers produced through radical addition‐fragmentation chain transfer (RAFT) controlled polymerization showed promising results . These latex NPs demonstrated high‐efficiency separations, electrophoretic mobility and migration range similar to SDS micelles, and compatibility with ESI‐MS detection.…”

CE and nanomaterials – Part II: Nanomaterials in CE

“…Latex NPs have also been employed as a pseudostationary phase, as shown in the works of Palmer et al. and Breadmore et al. .…”

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

“…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 .…”