Electroosmotic flow and injection: application to conductimetry

Electroosmotic solution propulsion and sample injection using fused silica tube was investigated. Capillary tube dimensions were 50-100 microm i.d. by 4-7 cm length with a break in the capillary wall near one end through which electrolytic contact with the capillary solution was established. The applied field was typically 150 V/cm. The voltage at the break in the column was monitored by potentiometry with a bridge configuration. Concentrations ranging from 10 microM to 100 mM were accommodated. The basis for high sensitivity, e.g. 70 mV/microM, together with low cell volume, e.g. 20 nl, was established. Tap water conductivity measurements were made using CaCl(2) reference solution.