Effect of diffusional bridging in multicapillary packing

Advances and Innovations in Liquid Chromatography Stationary Phase Supports

“…A much more fundamental approach to increase the loadability of OTLC consists obviously consists of combining multiple OTLC columns in parallel. This approach, pioneered by Zhdanov et al, however suffers from a problem called the polydispersity effect, implying that even very minor variations (order of 0.5%) in capillary-to-capillary diameter already lead to a dramatic reduction of the total achievable plate number. , Recently, Parmentier proposed the concept of diffusional bridging to overcome this problem . He showed theoretically that the system ultimately behaves like a particulate packing, however with the benefit of a pressure drop that is approximately 1 order of magnitude lower.…”

Microfluidic Validation of the Diffusional Bridging Effect Suppressing Dispersion in Multicapillary Flow Systems

“…Recently, − a ground-breaking concept has been proposed to suppress the polydispersity problem (Figure ). Rather than considering the capillaries in the bundle as individual capillaries each surrounded by an impermeable wall, they are conceived as individual parallel microchannels piercing through a monolithic block of mesoporous silica.…”

“…As a first step toward its practical exploitation, the DB principle is currently under implementation in the area of preparative chromatography, 21 where channel widths in the order of a few tens of micrometer are permissible. However, the currently employed manufacturing technique (multicapillary silica monoliths 21 ) leads to embodiments wherein the channel-to-channel distances vary so strongly that the ensuing geometry becomes too complex to describe, let alone to be amenable to a general analytical solution.…”

“…As a first step toward its practical exploitation, the DB principle is currently under implementation in the area of preparative chromatography, 21 where channel widths in the order of a few tens of micrometer are permissible. However, the currently employed manufacturing technique (multicapillary silica monoliths 21 ) leads to embodiments wherein the channel-to-channel distances vary so strongly that the ensuing geometry becomes too complex to describe, let alone to be amenable to a general analytical solution. Hence, in order to investigate the theoretical foundations of the DB principle, we opted for a manufacturing technology (silicon micromachining), 29 providing a much simpler geometry and offering a perfect control over the channel and wall dimensions.…”

“…The advantage of such diffusional bridging (DB) has been laid out theoretically in a series of papers, and its potential was confirmed by different authors. − They all found that the DB will induce a regime wherein the width of the chromatographic bands will only grow with the square-root of the elapsed distance, instead of growing linearly with the distance as is the case in the absence of diffusional bridging.…”