Solid-phase reactors in sequential injection analysis. Determination of manganese(II) in tap water and effluent streams using a solid-phase lead(IV) dioxide reactor in a sequential injection system

The determination of manganese(II) in tap water and effluent streams, using a solid-phase reactor incorporated into a sequential injection system was investigated. Mn²⁺-ions in samples injected into a carrier stream, were oxidised by solid lead(IV) dioxide suspended on silica gel beads to form MnO₄ ^–-ions which were detected spectrophotometrically at 526 nm. The linear range of the system is from 1 to 7 mg L^–1 with a detection limit of 0.62 mg L^–1. The proposed system is suitable for the determination of manganese(II) in tap and effluent streams at a rate of approximately 50 samples per hour with a relative standard deviation of better than 3%. Statistical comparison between the proposed sequential injection system and a standard ICP method revealed that there is no significant difference between the two methods at the 95% confidence level for effluent streams and at 99.9% for tap water.