Publications (4)12.73 Total impact
-
Article: Topographic structures and chromatographic supports in microfluidic separation devices.
[show abstract] [hide abstract]
ABSTRACT: A review is given of the literature on the design, development and use of micromachined devices for separations in the liquid phase. The emphasis is on those devices that offer more than just an empty channel for, e.g., electrophoretic separation. Topographic structures have been incorporated in the channels during their microfabrication, offering a variety of possibilities for the separation of (mainly) DNA molecules based on different principles. Supports for a stationary phase for chromatographic separations have been introduced in the channels in different ways: by packing of the channels with stationary phase particles, by polymerization of monolithic structures, or by lithographic machining of pillars in the channels. It is shown that the latter strategy gives the highest potential for increasing the separation power of the devices. Still, more conventional approaches are closer to a routine application.Journal of Chromatography 04/2008; 1184(1-2):560-72. · 4.53 Impact Factor -
Article: Experimental investigation of the band broadening originating from the top and bottom walls in micromachined nonporous pillar array columns
[show abstract] [hide abstract]
ABSTRACT: We report on the experimental investigation of the effect of the top and bottom wall plates in micromachined nonporous pillar array columns. It has been found that their presence yields an additional c-term type of band broadening that can make up a significant fraction of the total band broadening (at least if considering nonporous pillars and a nonretained tracer). Their presence also induces a clear (downward) shift of the optimal velocity. These observations are, however in excellent quantitative agreement with the theoretical expectations obtained from a computational fluid dynamics study. The presently obtained experimental results, hence, demonstrate that the employed high aspect ratio Bosch etching process can be used to fabricate micromachined pillar arrays that are sufficiently refined to achieve the theoretical performance limit.Journal of Separation Science 09/2007; 30(16):2605 - 2613. · 2.73 Impact Factor -
Article: Pillar-structured microchannels for on-chip liquid chromatography: evaluation of the permeability and separation performance.
[show abstract] [hide abstract]
ABSTRACT: The chromatographic characteristics were determined for a set of microfabricated separation channels structured with cylindrical and diamond-shaped pillars with a characteristic size of 5 microm. Channels with different structures and porosities were etched in a silicon wafer using lithographic techniques. The permeability for flow of the channels was shown to increase strongly with the overall porosity. Diamond-shaped pillars appeared to yield a slightly higher permeability than cylindrical pillars at the same channel porosity. Compared to packed columns, permeabilities were higher by a factor of up to 5. Band dispersion in the channels was measured with an unretained fluorescent probe compound using a fluorescence microscope. A relatively large variation in the observed plate heights between channels was found, which was mainly attributed to the inaccurate geometry of the structure close to the side walls. Reduced plate heights between 0.2 and 1.0 were obtained. The lowest plate heights were found for channels with low porosity. The chromatographic impedances were calculated and compared to the values for the traditional chromatographic systems. For one of the structured microchannels the impedance was found to be more than ten times lower than for a column packed with nonporous spherical particles. With the data collected, predictions are given on the possibilities in terms of efficiency and speed offered by structured microchannels for pressure-driven separations, taking practical constraints into account.Journal of Separation Science 08/2007; 30(10):1453-60. · 2.73 Impact Factor -
Article: Dual column capillary gas chromatographic system for the in situ analysis of volatile organic compounds on a cometary nucleus.
[show abstract] [hide abstract]
ABSTRACT: Two Wall Coated Open Tubular capillary columns, coated with poly(cyanopropylphenyl-dimethyl)siloxane and poly(diphenyl-dimethyl)siloxane stationary phases, have been selected for use in the COmetary SAmpling and Composition space experiment for the separation and identification of the wide range of volatile organic compounds which could be present in cometary nuclei. This article presents the main characteristics of the tandem column system for the analysis of solutes of cometary interest within the constraints of space instrumental operating conditions. The high efficiency of the columns is demonstrated and the influence of the operating conditions on their separation properties are investigated. The studied columns exhibit complementary retention pattern: their use in a dual column system makes it possible to achieve the separation and the identification of the compounds of interest. Finally, the good analytical behavior of the columns when analyzing samples which include large amounts of water, the main presumed volatile in comets, is demonstrated. The presented results thus show the suitability of the selected tandem columns system for the desired analyses, and their performance on adaptation to in-situ cometary chemical investigation.Journal of Separation Science 06/2004; 27(7-8):495-503. · 2.73 Impact Factor
Top co-authors
Top Journals
Institutions
-
2007–2008
-
Universiteit van Amsterdam
- Van 't Hoff Institute for Molecular Sciences
Amsterdam, North Holland, Netherlands
-
