The Retention Characteristics of a Novel Phenyl Analytical Scale First Generation Monolith

Abstract

As of yet the commercial options of analytical scale silica monoliths are still limited to: silica, C8 and C18. Hence this study highlights the advantages of a novel phenyl first generation analytical scale silica monolith to overcome the limited selectivity, and provide a column capable of P-P interactions and high-throughput=low backpressure (<400 bar) separations.The retention characteristics of both non-endcapped and endcapped surfaces were chromatographically studied via: the height equivalent to a theoretical plate (HETP) curves to compare the efficiency as a function of linear velocity; the Tanaka test to compare six surface properties (hydrophobicity, steric selectivity, hydrogen bonding capacity, amount of alkyl chains, and ion exchange sites under acidic and basic conditions); the linear solvent strength (LSS) model to illustrate the methylene and phenyl selectivity. Additionally, the stability testing of both surfaces, throughout the chromatographic testing, demonstrates no degradation of the surface or column bed.HETP curves improved after endcapping, further more, the Tanaka test's hydrogen bonding value also reduced by 35%, indicating the minimization of the residual silanol groups. The LSS model showed excellent linearity for both surfaces (R 2 > 0.991), and the phenyl endcapped monolith had comparable aromatic selectivity to a phenyl particle packed column.

A non-destructive test to assess the axial heterogeneity of in situ modified monoliths for HPLC

“…7,8 To overcome these limitations, researchers have used in situ silylation reactions to modify commercial bare-silica monoliths with a desired moiety. [9][10][11][12][13][14][15] However, this modication procedure is not always reproducible. 9 While a number of different chromatographic tests can elucidate separation performance, [16][17][18][19][20][21] the surface coverage of the bonded ligands cannot be measured without destroying the column.…”