The DPD method for determining chlorine is internationally accepted as the method that gives the best overall accuracy and precision. This method is approved by the U.S. EPA as a method for regulatory reporting. The DPD tablet No.1 is used to measure free or "available" sanitizer, the useful hypochlorous acid required for sanitizing. DPD tablet No.3 is used after DPD No.1 to measure total chlorine. The difference between the two measurements is the combined chlorine (chloramine) value. Chloramines are an undesirable form of chlorine which do not sanitize and can cause irritation.
Use DPD1 to measure for free chlorine
Add DPD3 to the same sample to measure the total chlorine
Use DPD4 if you want to measure total chlorine only
Tablets are individually packaged in aluminum foil. Shelf life is 2 years. Packed 100 tablets per pack.
