Fig. 3 shows the FIA responses for various concentrations
of DA under the optimized conditions. A linear calibration
plot was obtained for 0.4–20 lM DA with a slope
of 14.2 nA/lM. The detection limit (S/N = 3) was
0.05 lM. The relative standard deviation was 0.2% for 10
continuous injection of 4 lM DA standards. The working
system is highly stable for continuous flow for 5 h without
considerable loss of the reduction current. The performance
is comparable to the reported flow amperometry
using carbon nanotube-modified electrode [12] and is better
than that using biosensor [13].