Chemical reagent for water analysis
LaMotte Company
The DPD is the most widely used reagent for determining free and combined chlorine. DPD #1 will quickly reveal the precise level of free chlorine. The DPD # 3 measures the level of combined chlorine. Combined chlorine is a sanitizer that has reacted with impurities in the water and is, therefore, less capable of sanitizing. To test for combined chlorine, simply add a DPD #3 tablet to the free chlorine water sample. A measurable increase in sample color will occur. This measurement is the amount of total chlorine in the sample. Subtract the free chlorine measurement from the total chlorine result to obtain your combined chlorine reading.
