A microlithographically fabricated iridium ultramicroelectrode array i
s used to provide a disk array for formation of mercury microhemispher
es. The mercury ultramicroelectrode array (Hg UMEA) shows a response w
ith chronoamperometry and square wave anodic stripping voltammetry equ
ivalent to that expected for a single Hg UME. The array, made up of 19
interconnect ed 10-mu m-diameter UMEs, provides a multiplication of t
he signal current proportional to the number of UMEs in the array, wit
hout any indications of overlap of the diffusion fields. Deposited mer
cury on the iridium disks is physically and chemically stable with no
indication of degradation or dissolution of the iridium pads even afte
r several days of use. This microlithographically fabricated device pr
ovides a stable, well-defined, and reproducible array of mercury ultra
microelectrodes. The analytical utility and performance of the Hg UMEA
is demonstrated by the analysis of Cd(II), Pb(Il), and Cu(II) in neat
spring water samples.