F. Bjorefors et al., Electrochemical detection based on redox cycling using interdigitated microarray electrodes at mu L/min flow rates, ELECTROANAL, 12(4), 2000, pp. 255-261
The influence of convection on the degree of redox cycling at interdigitate
d microarray electrodes in a flow system was investigated in the end column
detection mode for flow rates below 20 mu L/min. It was found that the deg
ree of redox cycling increased with decreasing flow rates and values of 2.9
and 2.2 were obtained for a flow rate of 2 and 20 mu L/min, respectively u
sing photolithographically fabricated interdigitated arrays consisting of 1
40 microbands separated by 6 mu m. The obtained degrees of redox cycling we
re lower than the value of 4.4 obtained in a stationary solution in the bat
ch mode as a result of a decreased collection efficiency between adjacent m
icrobands and a relatively low conversion efficiency at each microband in t
he presence of the flow It is shown that a collection efficiency of more th
an 90 % is needed to produce an order of magnitude increase in the current
due to redox cycling in a stationary solution. When using a microarray elec
trode consisting of 280 microbands in a thin layer flow cell, a conversion
efficiency of close to 100 % could be obtained at flow rates below 1 mu L/m
in. In the latter case, a significantly larger flow rate dependence of the
current was found compared to that for a single microband electrode.