. A wide-bore capillary allows a
mercury drop to be grown very rapidly when the valve is opened. Three valve
opening times produce drops that are described as small, medium, or large.
Since the potential scan is accomplished after the valve has been closed (i.e.,
stationary electrode), charging-current contributions due to the drop growth
are eliminated. All the components of this electrode, including the mercury
reservoir, are contained in a compact unit. Such a commercial probe allows
the conversion from the HMDE to DME by a single switch. When used in the
DME mode, it exhibits a very rapid growth to a given area, which then remains
constant (as desired for minimizing charging-current contributions). The performance
of HMDEs can be improved by siliconizing the interior bore of the
capillary.