Miniature microplasma carbon optical emission spectrometry for detection of dissolved oxygen in water

Abstract

As one of the most important quality parameters of natural water, the quantification of dissolved oxygen (DO) attracts considerable attention in environmental analytical chemistry. In this work, an accurate and novel strategy based on selective oxidation reaction and miniature point discharge optical emission spectrometry (μPD-OES) is proposed for the simple, fast, and efficient quantitative analysis of DO in natural water samples. The DO present in the tested sample can easily oxidize an equivalent amount of manganese ions (Mn2+) to an insoluble precipitate of manganese hydroxide (Mn(OH)3) under alkaline conditions. The precipitate is able to convert oxalate to carbon dioxide (CO2) in the presence of H2SO4. Consequently, the determination of DO is accomplished via the detection of CO2 by μPD-OES at 193.0 nm. Under the optimum conditions, a limit of detection for DO detection was 0.016 mg L−1. Besides, a good precision of 3.8% was obtained for the determination of DO. Finally, the DO in tap water, river water, and lake water samples was successfully analyzed and the obtained results are in good agreement with those obtained by a Chinese national standard method (GB 7489-87), thus demonstrating that the proposed method retains a remarkable potential for the on-site analysis of DO in environmental surface water samples.