EZ-DPD™DPD Dispenser for Chlorine Testing IDEXX EZ-DPD makes chlorine testing easy. Its compact design allows you to:
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EZ-DPD™ is easy to use, rapid and accurate
Easy
- Eliminates foil packets
- Recessed mouth fits different sized sample vials
- Works with wide range of color cubes, color wheels and colorimeters
- Color coding distinguishes free and total chlorine tests
Rapid
- Dispenses reagent in one quick step
- Reduces hands-on time
- Refill vials screw on quickly and easily
Accurate
- U.S. EPA accepted—Standard Methods for the Examination of Water and Wastewater, Section 4500-Cl, G
- Eliminates risk of powder trapped in corners of foil pouches
Cost Effective
- Low cost per test
- Speeds sampling time
Scientific Basis: How EZ-DPD™ Works
EZ-DPD dispenses a pre-measured dose of N, N-Diethyl-p-phenylenediamine (DPD) into a 5 mL or 10 mL sample. The DPD reacts with chlorine in the sample to produce a pink color change. The intensity of the color is proportional to the amount of chlorine in the sample. Colorimetric test kits (not currently sold by IDEXX) allow the sampler to interpret the intensity of the color change, providing a quantitative measure of the amount of chlorine in the sample. EZ-DPD detects chlorine between 0.1–4 parts per million (ppm).
How to use EZ-DPD™ | |
Dispensing
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Refilling
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Compatibility
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EZ-DPD Questions and Answers
What chlorine testing is required by the U.S. EPA? 
The Surface Water Treatment Rule of 1989 requires that distribution systems using surface water as a source and serving more than 25 people disinfect the distribution system or meet maximum HPC levels. Disinfectant residual level must be ≥ 0.2 mg/L (ppm) or the HPC level must be below 500 cfu/mL. The disinfectant residual must be present in ≥ 95% of samples for 2 consecutive months.
Testing frequency requirements:
| POPULATION SERVED | MINIMUM # SAMPLES/DAY |
| < 500 | 1 |
| 501 - 1000 | 2 |
| 1001 - 2500 | 3 |
| 2501 - 3300 | 4 |
| > 3300 | continuous |
Chlorine present as Cl2, HOCl and OCl- is free available chlorine. The active chlorine in the water for disinfection is also called free chlorine residual.
Chlorine that is bound to other elements or organic compounds but is still an effective disinfectant. Combined chlorine has been found to be more effective than free chlorine in controlling post-disinfection bacterial growth. Chloramines are an example of combined chlorine.
Chloramines are compounds formed by the reaction of chlorine and ammonia-nitrogen in water.
Residual chlorine is the chlorine that has not combined with organic matter.
What is the amount of DPD powder delivered by the EZ-DPD dispenser?
The EZ-DPD dispenser will deliver 0.04–0.09 grams of DPD powder each time the button is pressed.
What is the chlorine ppm detection range of the EZ-DPD test?
The DPD test detection range is from 0.1–3.5 ppm.
Standard Methods for the Examination of Water and Wastewater, Section 4500-CI, G describes the DPD Colorimetric method for field testing chlorine.
Can I use EZ-DPD for testing 25 mL samples?
Yes. Press the button three times for each 25 mL sample.
What should be done if the EZ-DPD dispenser is plugged?
Remove the dispenser from the vial and clean it to dislodge anything clogging the dispenser. This can be done with a swab or other small device. The dispenser can also be cleaned with water. If you clean the dispenser with water, make sure that the dispenser is dry before putting the dispenser back on a vial of reagent.
What should be done if IDEXX DPD powder has clumped?
If the powder clumps, shake the vial to ensure free-flowing powder before dispensing.
What chlorine testing products will EZ-DPD work with?
EZ DPD is capable of working with many products on the market, including: Hach™ Pocket Colorimeter™, Hach color wheel, Hach color cube, Lamotte™ colorimeter.
