Determination method of water sample with high chlorine content by COD rapid analyzer

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by：BOQU 2022-03-31

For water samples with high chlorine content, the interference can be avoided by adding a mercury sulfate masking agent. Generally, when the COD value is above 50 mg/L and the chloride ion concentration is above 2000 mg/L, the dilution method can be used. Dilute the water sample with distilled water to make the chloride ion content less than 2000mg/L, and then use this method for analysis.

Take 3ml of well-mixed water sample or a representative sample whose chloride ion content is less than 2000mg/L after dilution and well-mixed, and put it into a cleaned and stoppered graduated digestion tube, and then add masking agent to the tube for 3 to 4 drops (make sure the weight ratio of mercury sulfate to chloride ions is 10:1)

1ml of special oxidant, 5ml of catalyst liquid for analysis, shake well. Insert the reaction tube into the heating hole of the digestion device, press the digestion button after the temperature rises to the set temperature, and the instrument will automatically and periodically digest it. After 15 minutes, take out the test tube and place it on the test tube rack to cool for 2 minutes and then cool to room temperature with water.

Adjust the liquid volume of each test tube to the 12ml mark with distilled water, shake well, if there is precipitation, you need to stand to take the supernatant, put it at the injection port, press the measure button, and measure the COD value of the sample according to the operation prompts.