Determination of chemical oxygen demand by a flow injection method based on microwave digestion and chromium speciation coupled to inductively coupled plasma optical emission spectrometry

► New insights in the determination of COD in water samples are introduced. ► This is a low-sample handling strategy that proposes an in-flow microwave digestion. ► This method is inching to column solid phase extraction with activated carbon. ► This FI-SPE method enables de determination of samples with high Cl− concentration. ► A noticeably reduction in time and wastes of analysis are remarked.