An environmental friendly procedure for photometric determination of hypochlorite in tap water employing a miniaturized multicommuted flow analysis setup.

Abstract

A photometric procedure for the determination of ClO(-) in tap water employing a miniaturized multicommuted flow analysis setup and an LED-based photometer is described. The analytical procedure was implemented using leucocrystal violet (LCV; 4,4',4''-methylidynetris (N,N-dimethylaniline), C(25)H(31)N(3)) 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 consumption, 2.4 μg of LCV per determination, a linear response ranging from 0.02 up to 2.0 mg L(-1)  ClO(-), a relative standard deviation of 1.0% (n = 11) for samples containing 0.2 mg L(-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.