Microfluidic Chemiluminescence System with Yeast Saccharomyces cerevisiae for Rapid Biochemical Oxygen Demand Measurement

A new automated chemiluminescence method resorting to sequential injection analysis (SIA) was developed to rapidly determine biochemical oxygen demand (BOD). The assay is based on the redox reaction between quinone and Baker’s yeast in the presence of organic substances. The formed active oxygen species reacted with luminol, under the catalytic action of ferricyanide, and increased chemiluminescence signal. The automation of the assay ensured a precise control of the reaction conditions and enabled a reduction of more than 75-times in the reagents consumption and effluents production comparatively to BOD5. The sampling rate was widely improved with a flow rate of 8 cycles per hour. The method was applied to determine the BOD of ionic liquids (ILs) incorporating different chemical elements and deep eutectic solvents (DESs) combining choline chloride with varying hydrogen-bond donors. Differences in BOD and biodegradability were observed between tested compounds, with DESs showing, in general, higher BOD values and greater biodegradation than ILs. The results obtained in the developed bioassay demonstrated statistical correlation with the BOD5 method. Therefore, the developed methodology is a simple, economic and high-throughput alternative screening bioassay to the conventional method, with the potential to preliminarily assess the potential biodegradability of chemicals in the environment.