A.

probe arena

B.

D vs 1/a Graph

C.

3dvis efficiency

D.

aset efficiency

Fig. 2. Ion selective microelectrode.   A. Artificial diffusional-source arena for calibrating a scanning ion-selective electrode (SIET).   B. Probe tip with ion-selective liquid ion exchanger (LIX), electrolyte and Ag/AgCl wire in place.   C. Old 3DVIS 3-D sampling protocol using oscillating motion.   D. New ASET 3-D sampling rule approach.