Chlorine Test:The smell of disinfectant can be smelled, but the test water sample does not show color?


Chlorine is one of the indicators that water quality testing often needs to determine.

Recently, the editor received feedback from users: When using the DPD method to measure Chlorine, it clearly smelled a heavier smell, but the test did not show color. What is the situation? (Note: The user's disinfectant margin requirements are relatively high)

Regarding this phenomenon, let’s analyze with you today!

First of all, the most widely used method for detecting chlorine is DPD spectrophotometry. According to EPA: The residual chlorine range of the DPD method is generally 0.01-5.00 mg/L.

Secondly, hypochlorous acid, the main component of free chlorine in water, has oxidizing and bleaching properties.Use the DPD method to measure residual chlorine in water: When the chlorine content in the water sample is too high, after DPD is completely oxidized and developed, more chlorine will show the bleaching property, and the color will be bleached, so it will appear This phenomenon of the problem at the beginning of the article.

In view of this situation, the following two solutions are recommended.

1. When using the DPD method to detect chlorine, you can dilute the water sample with pure water so that the chlorine is within the range of 0.01-5.00 mg/L, and then perform the detection.

2. You can directly select equipment that detects high concentration of residual chlorine for detection.

Post time: Sep-29-2021