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

Abstract

The efficiency of liquid chromatography separations could be strongly improved by changing the current packed bed columns by a bundle of parallel capillary tubes. In practice, however, the polydispersity effect, which emanates from the inevitable small differences in capillary diameter, completely ruins this potential. The concept of diffusional bridging, introducing a diffusive cross talk between adjacent capillaries, has recently been proposed to resolve this. The present contribution provides the first experimental proof for this concept and quantitatively validates its underlying theory. This has been accomplished by measuring the dispersion of a fluorescent tracer in 8 different microfluidic channels with different degrees of polydispersity and diffusional bridging. The observed degree of dispersion reduction agrees very well with the theoretical predictions, hence opening the road to the use of this theory to design a new family of chromatographic beds, potentially offering unprecedented performance.

Column-Only Band Broadening in a Porous Shell Radially Elongated Pillar Array Column

“…Under gradient conditions, this inlet skew would not be important, as the peak would be focused on the column anyhow. Since the classic approach to determine the plate height via the peak width is known to be inaccurate with skewed peaks, the peak deconvolution method , has been used to eliminate the effect of the inlet skew.…”

“…A routine was implemented in MATLAB to determine the on-column dispersion using the peak deconvolution principle. This routine is described in earlier work , and in the Supporting Information and consists of the following steps. First, the Fourier transformed signals of the initial and downstream peaks were calculated by using the MATLAB implementation of the “fast Fourier transform” algorithm.…”