Evaluation of 5 μm Superficially Porous Particles for Capillary and Microfluidic LC Columns

Abstract

Large-size (4–5 µm) superficially porous particles yield lower plate heights (e.g., the minimal reduced plate height or hmin ≈ 1.5) than fully porous particles of a similar size when packed into large-bore columns. This property allows for better chromatographic performance without the higher pressures required for smaller particles. This study explores the use of such particles in microfluidic LC columns where materials and fitting pressure limits can constrain the size of particle used. The theoretically predicted performance improvements compared to fully porous particles were not demonstrated in capillary columns (with hmin ≈ 2 for both particle types), in agreement with previous studies that examined smaller superficially porous particles. Microfluidic columns were then compared to capillary columns. Capillary columns significantly outperformed microfluidic columns due to imperfections imposed by microfluidic channel asymmetry and world-to-chip connection at the optimal flow rate; however, superficially porous particles packed in microfluidic LC columns had flatter plate height versus flow rate curves indicating potential for better performance at high reduced velocities.

Signal convolution indicates chromatographic pulse flow and open-end flow

“…Separation by chromatography and identification of chemical species by various types of analytical technologies are key in analytical chemistry activities [1]. Recent developments in chromatography include analysis of chiral compounds [2], high-speed analysis [3][4][5], microanalysis [6][7][8], nano analysis [9] and lab-on-a chip [10]. The optimization and understanding of chromatographic systems rely on two theories or combinations thereof: adsorption theory [11,12] and plate theory [13,14].…”

“…Peak broadening [25] originates from several contributions comprising longitudinal diffusion, eddy diffusion, mobile-phase mass transfer, stagnant-mobile-phase mass transfer and stationary-phase mass transfer [26]. The efficacy of peak separation and retention depends on the column length, temperature [27], particle size of the stationary phase, porosity of the column material [14,28], column packing [29,30], flow rate [7], diffusion rate and, to a large extent, composition of the mobile phase [31]. In high-performance liquid chromatography (HPLC), changing the solvent composition of the mobile phase corresponds to an adjustment of the hydrophobic and hydrophilic interactions among the solute, mobile phase and stationary phase [31,32].…”

Fundamental to achieving fast separations with high efficiency: A review of chromatography with superficially porous particles

“…Here, the efficiency was found to increase with decreasing capillary id (Fanali et al, 2013). In another study, the loading of larger SPPs (4-5 μm in size) (Grinias & Kennedy, 2015) resulted in a h min of 1.5 with flatter h-ν (Equation 16) response than for TPPs.…”

High-Throughput and Ultrafast Liquid Chromatography

“…Capillary LC techniques continue to remain an important part of the separations field, ,, but work on high-throughput approaches with capillary LC have been limited because it is primarily used for long, shallow gradient runs in proteomic analysis. Although there have been some reports of separation methods in the 1–2 min range, , most of the recent fundamental work in this area has involved the development of new instrument components toward the development of small and/or portable capillary LC platforms with more traditional LC separation times. − One area that saw progress was the use of submicrometer colloidal silica packings in capillaries with extremely high chromatographic efficiency, which enabled a 2 min separation of three proteins and a separation of monoclonal antibody (mAb) aggregates in under 1 min . The potential for increased applicability of capillary columns in ultrafast LC separations was recently demonstrated using a 2.7 cm long, 2 μm (i.d.)…”