Background Using the jump in potential, potentiometric titration method is theoretically more objective in predicting the end points of titrations than acidic potassium permanganate method which is based on visual colorimetry.
Objective This study compares the main differences between potentiometric titration method and acidic potassium permanganate method in determination of oxygen consumption in drinking water.
Methods Using the same pretreatment as the acidic potassium permanganate method did, the differences between the two methods were investigated from selected aspects of liquid adding volume, titration speed, titration temperature, and determination results of practical samples.
Results With smaller liquid adding volume, controllable titration speed, and objective judgment of titration end point, potentiometric titration method had higher sensitivity, precision and reproducibility. When the samples were spiked with standard solution at 1.40 and 2.79 mg/L respectively, the recoveries of the potentiometric titration method were 95.1%-107.9% and 99.5%-101.0% respectively, and the relative standard deviations were 0.9%-3.7% and 0.8%-1.2% respectively. The oxygen consumption were accurately determined within the concentration of 5.5mg/L.
Conclusion Potentiometric titration method is suitable for determination of oxygen consumption in drinking water.
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