Optimization of the response of phosphate separated by capillary zone electrophoresis

The response of phosphate, which is highly variable in capillary zone electrophoresis (CZE) using silica capillaries, was optimized by monitoring the absorption of phosphate onto the capillary surface. A capillary conditioning regime is described which facilitates maximum response for phosphate without significantly extending the total analysis time. The described regime also allowed excellent precision (?0.36%sr, n= 10) to be achieved with regard to absolute migration time for phosphate as well as chloride, bromide, sulfate and hydrogencarbonate. Using this regime, the precisions for the phosphate peak area and height were 9 and 5.5%sr, respectively (n= 10).