Sealing and Chromatographic Performance of Microgroove Columns

In a recent paper, we introduced the concept of structured microgroove columns as a potential solution to obtain perfectly ordered particle beds for nano- and micro-LC. In this concept, spherical particles are either individually positioned (single layer column) or stacked (multilayer column) in a series of interconnected micromachined pockets. After introducing a suitable method to fill the columns efficiently in a one-particle-per-pocket mode, the present contribution addresses the issue of sealing the filled columns and reports on the first flow tests conducted in a microgroove column device. For this purpose, an adapted set of micromachined columns was filled with 10 μm calibrated silica particles and subsequently anodically bonded to a borofloat top plate. The potential chromatographic performance of this first prototype is determined by injecting a band of fluorescent dye into the unretentive column. Reduced plate heights were higher (h_min = 2 instead of = 1) than theoretically expected, while pressure drop and flow resistance were much closer to the expected value (ϕ = 120 versus 130 expected). It is assumed the plate height deviations from theory are due to the fact that the pockets were somewhat oversized (some 75%), creating unnecessary large dead spaces.