Comparison of capillary zone electrophoresis performance of powder-blasted and hydrogen fluoride-etched microchannels in glass

The applicability of glass chips with powder‐blasted microchannels for electrophoretic separations was examined, and the performance was compared to microchannels etched with hydrogen fluoride (HF), using bicarbonate buffer and rhodamine B and fluorescein as model compounds. The measured electroosmotic mobilities in all chips were comparable, with values of ca. 7×10‐4 cm2 V‐1s‐1. The effect of electrical field strength and detection length on the separation efficiency was monitored. It was found that the main source of dispersion is of the Taylor‐Aris type, which was discussed in relation to channel roughness differences. Although in powder‐blasted channels with a separation length of 8.20 cm, 7–9 times lower plate numbers were obtained than in a HF‐etched channel with similar dimensions, successful separation of five fluorescein isothiocyanate (FITC)‐labeled amino acids was obtained on a powder‐blasted chip within 80 s. Efficiencies of up to 360 000 plates/m were demonstrated on this chip, when a higher buffer concentration was used at a field strength of 664 V/cm. It can be concluded that powder‐blasted microchannel chips, although they have a lower separation efficiency compared to HF‐etched chips, perform well enough for many applications. Powder blasting can therefore be considered a low‐cost and efficient alternative to HF etching, in particular because of the possibility to fabricate access holes through the glass with the same process.