COMOSS

Slentz et al. [133] described the effects of geometry (size, shape, and dimensions) on the performance of COMOSS. Vreeland and Barron [134] described the design of functional materials for genomic and proteomic analyses in NCE. The authors discussed different polymer chemistries for micro-channel surface passivation and improved DNA separation. 

Figure 2.16 Representation of (a) layout of a typical COMOSS separation column and (b) an SEM image showing the microfabricated inlet splitter [115].

Slentz et al. [23] described nanocapillary electrochromatography on collocated monolithic support structures (COMOSS) molded in PDMS. The authors fabricated a chromatographic channel by molding COMOSS directly. In addition, the ability to separate biological samples such as peptides from a... 

To increase the surface area of the stationary phase for CEC separation, a collocated monolithic support structure (COMOSS) was constructed in a Si chip. A polystyrene-sulfonic acid stationary phase was then immobilized [349]. Design of the COMOSS required that the combined cross sectional area at the column head to be the same at any point in the inlet distributor [644]. A study for the reduction of band broadening in COMOSS was also reported [645]. 

The COMOSS has also been fabricated on a PDMS chip for CEC separation of FITC-labeled peptides (Figure 6.25). However, in the CEC separation of a mixture of rhodamine and fluorescein, a broad rhodamine peak was obtained, but fluorescein did not have this problem. This was possibly because the neutral rhodamine had diffused into the PDMS substrate, as illustrated in the fluorescent image in Figure 6.26 [360]. In another report, CEC separation of a peptide mixture was performed on a PDMS chip after cerium(IV)-catalyzed polymerization of the stationary phase within the channels [646]. 

FIGURE 6.25 Scheme of a COMOSS column incorporated in a PDMS chip for CEC separation. A reverse-phase coating (poly[styrenesulfonic acid]) was bonded to the COMOSS column after silanization treatment of the PDMS surface. Since the usual solvent (toluene) for silanization cannot be used in PDMS, the surfactant, SDS, was used to help dissolve the silanes [360]. Reprinted with permission from Wiley-VCH Verlag. 

FIGURE 6.26 Fluorescence image of unmodified PDMS COMOSS column (lOx) following incubation with rhodamine 110 for 2 days [360]. Reprinted with permission from Wiley-VCH Verlag. 

COMOSS collated monolithic support stmcture cP centipoise (a viscosity unit)... 

Peptide mapping ovalbumin, Cl8 COMOSS Acetonitrile-10 mM 1.5 pm wide, 10 pm 700 s needed for run... 

The COMOSS column was estimated to be equivalent to a conventional 4 pm non-porous bead packing. In addition, the surfaces of the structures were functionalized with a silane to form a C18 reversed-phase monolayer. To obtain the nanoliter per minute flow rates required to operate the devices, the authors relied on electroosmotically-driven flow using an electric field of 770 V cm thus operating in CEC mode, since mechanical HPLC pumps available at the time were not capable of delivering such a small flow at the pressures required. However, the column efficiency obtained was remarkable, with some 35 000 plates (777 000 plate m ) in 110 s obtained for unretained Rhodamine 123 on a column... 

Fig. 9.7.3 (Left) Depiction of the COMOSS column configuration with injection cross and ports. (Right) Detail of a photolithographically-defined COMOSS stationary phase support structure.

Cardiac Rehabilitation A Guide to Practice in the 21st Century, edited by Nanette K. Wenger, L Kent Smith, Erika Sivarajan Froelicher, and Patricia McCall Comoss... 

The column itself can be produced as a single open channel or as a branched system of channels starting from one microchannel and ending in another microchannel. The latter type is often named as COMOSS (collocated monolith support structure). With some of the materials mentioned, the channels can serve as stationary phase itself or can be functionalized by coating, packing, or incolumn polymerization with appropriate chromatographic phases. 

Figure 7.4 COMOSS. Microchannels through a maze of pillars.

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