A photometric procedure for the determination of ClO- in tap water employing a miniaturized multicommuted flowanalysis setup and an LED-based photometer is described. The analytical procedure was implemented using leucocrystal violet (LCV; 4,4, 4-methylidynetris (N,N-dimethylaniline), C25H31N3) as a chromogenic reagent. Solenoid micropumps employed for solutions propelling were assembled together with the photometer in order to compose a compact unit of small dimensions. After control variables optimization, the system was applied for the determination of ClO- in samples of tap water, and aiming accuracy assessment samples were also analyzed using an independent method. Applying the paired t-test between results obtained using both methods, no significant difference at the 95% confidence level was observed. Other useful features include low reagent\nconsumption, 2.4 �µg of LCV per determination, a linear response ranging from 0.02 up to 2.0 mgL-1 ClO-, a relative standard deviation of 1.0% (n = 11) for samples containing 0.2 mgL-1 ClO-, a detection limit of 6.0 �µg L-1 ClO-, a sampling throughput of 84 determinations per hour, and a waste generation of 432 �µL per determination.
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