This paper describes the use of flow injection (FI) techniques for the dete
rmination of iodine in urine, based on the catalytic effect of iodide in th
e redox reaction between Ce(IV) and As(III). The proposed procedures minimi
ze errors in the conventional batch method arising from the reading of abso
rbance at a fixed time after addition of Ce(IV) reagent. Two FI systems, fo
r the continuous and stopped modes of operation were assembled. In the cont
inuous-FI system, a thermostated bath was used to increase the sensitivity.
However this is not necessary for the stopped-FI system. The two systems a
re comparable in terms of sensitivity, sample throughput and detection limi
t. The continuous-FI and the stopped-FI exhibited detection limits (3 sigma
) of 2.3 and 3 mug I 1(-1) respectively. Both systems have equal sample thr
oughputs of 35 samples h(-1). Calibration plots for both techniques are lin
ear. The FI procedures provide very short analysis times compared to the ba
tch procedure. Using the linear regression test, then is no significant dif
ference between the results from the four methods, i.e., continuous-FI, sto
pped-FI, conventional method and ICP-MS. The proposed methods are readily a
pplicable for automation and can be an alternative to the conventional proc
edure for the survey of the iodine deficiency disorder. A condition for sam
ple digestion is also proposed to reduce the amount of chloric acid require
d for complete digestion. Kinetic information of the reaction can also be o
btained from the stopped flow mode.