Integrated capillary electrophoresis devices with an efficient postcolumn reactor in planar quartz and glass chips

Methods to fabricate planar capillary electrophoresis devices integrated with a postcolumn reactor in fused silica (guard) and Pyrex glass are presented. Quartz is etched at similar to 1 mu m/min with a 2.1:1 width-to-depth ratio using a Cr/Au/Cr metal mask and concentrated HF/HNO3. On-chip postcolumn reaction of o-phthaldialdehyde (OPA) and amino acids gave theoretical plate numbers up to 83 000 and similar to 90 ms peak widths, corresponding to 14 plates/V and a 0.5 mu m theoretical plate height. The reactor geometry caused only a 10% degradation in efficiency.