Facultade de Fisioterapia

Miniaturized and green method for determination of chemical oxygen demand using UV-Induced oxidation with hydrogen peroxide and single drop microextraction

Authors: J. Akhoundzadeh, M. Costas, Isela Lavilla, M. Chamsaz, Carlos Bendicho

Journal: Microchimica Acta, 180: 1029-1036, 08/2013

DOI: https://doi.org/10.1007/s00604-013-1024-5


Abstract

We report on a green method for the determination of low levels of chemical oxygen demand. It is based on the combination of (a) UV-induced oxidation with hydrogen peroxide, (b) headspace single-drop microextraction with in-drop precipitation, and (c) micro-turbidimetry. The generation of CO2 after photolytic oxidation followed by its sequestration onto a microdrop of barium hydroxide gives rise to a precipitate of barium carbonate which is quantified by turbidimetry. UV-light induced oxidation was studied in the absence and presence of H2O2, ultrasound, and ferrous ion. Determinations of chemical oxygen demand were performed using potassium hydrogen phthalate as a model compound. The optimized method gives a calibration curve that is linear between 3.4 and 20 mg L−1 oxygen. The detection limit was 1.2 mg L−1 of oxygen, and the repeatability (as relative standard deviation) was around 5 %. The method was successfully applied to the determination of chemical oxygen demand in different natural waters and a synthetic wastewater.