2.4. Experimental procedure
The BOD biosensor was inserted into the detection chamber containing 50 mL of 10 mM phosphate buffer (pH7.0) solution
saturated with air, while continuously stirring with a magnetic bar.The detection chamber was maintained at 30 1C using a thermostat. The response of the BOD biosensor was estimated by steady state current analysis.When the current of the oxygen electrode reached a steady state,the sample solutions were added to the 50 mL phosphate buffer solution. The current of the oxygen electrode decreased and reached a steady state in a few minutes.The response was recorded as the difference between the steady state current before and after addition of the sample.