Fig. 4 Effect of pH of buffer solution on mean migration time of As(V) DMA and PO₄ with the verticle axis in mV. Separation column, 720-mm by 50-µm i.d. fused capillary tube; support electrolyte chromate buffer 5 mmol L^-1 with 0.5 mmol L^-1 EOF modifier; applied voltage 20 kV ([As] and