Envco – Environmental Equipment

Methods

The DPD Method
In the USEPA-approved DPD methodology, free chlorine reacts with DPD to form a pink product. When ammonia or amines are present, some of the chlorine may exist as combined chlorine. Combined chlorine will not interfere with the free chlorine results, provided the readings are taken at one minute. To determine total chlorine (the sum of free and combined), use the A-2500 Activator Solution (potassium iodide) supplied in the kit. Results are expressed as ppm (mg/L) Cl2.

The DDPD Method
The DDPD method is derived from the DPD method. Test kits that employ this chemistry are well suited for use where biocides and chromate corrosion inhibitors are used simultaneously. DDPD reactswith free chlorine to form a purple product. When ammonia or amines are present in the sample, some of the chlorine may exist as combined chlorine. To determine total chlorine (the sum of free and combined), use the A-2500 Activator Solution (potassium iodide) that is supplied in the kit. Results are expressed as ppm (mg/L) Cl2.

CHEMetrics' DDPD method is also applicable to the direct determination of hypochlorite concentrations in various cleaning preparations and disinfectants prior to their dilution. The DDPD compound reacts with hypochlorite ions to form a purple color. Results are expressed as percent (%) NaOCl.

How to use a CHEMets Kit
To perform a test, immerse the CHEMet ampoule into the sample and snap off the tip (Step 1)- the correct volume of sample is automatically drawn in, filling the ampoule; a small inert gas bubble remains in the ampoule. To facilitate mixing the sample and reagent, tilt the ampoule back and forth so the bubble travels from end to end (Step 2). In 2 minutes or less, quantify the result by comparing the filled ampoule to the appropriate color standard(s) (Step 3). For higher concentrations, the flat comparator is used. For lower concentrations, the round comparator is used. The ampoule is compared with the standards until a color match is found. Kits include 30 ampoules, comparator(s), accessory solution(s)(when necessary), a sample cup, and instructions. Refill packs of 30 ampoules and accessory solutions are available separately. Comparators have a 2-year shelflife. Material Safety Data Sheets are provided in test kits. CHEMets ampoules are designed for maximum simplicity and accuracy. Each glass ampoule is 7 mm in diameter, 100 mm in length, with a tapered, pre-scored tip; reagents are vacuum-sealed inside.

Ordering Information:

Analyte: CHLORINE (free & total)
Method: DPD METHOD (EPA-approved in many states for reporting drinking water data).
Type: CHEMet

K-2504 Chlorine 0-1 and 1-5 PPM

Analyte: CHLORINE (free & total)
Method: DDPDtm CHEMISTRY (Proprietary chemistry providing more resistance to interferences than DPD).
Type: CHEMet and Ultra-Low-Range (ULR) CHEMet

K-2511 Chlorine 0-0.20 PPM
K-2505 Chlorine 0-1.0 and 1.0-5.0 PPM

Analyte: CHLORINE (free & total)
Method: DDPDtm CHEMISTRY (Proprietary chemistry providing more resistance to interferences than DPD).
Type: VACUettes

K-2505D 0-30 and 30-150 PPM
K-2505A 0-60 and 60-300 PPM
K-2505B 0-120 and 120-600 PPM
K-2505C 0-1000 and 1000-5000 PPM

Test kits contain 30 ampoules, snap cup, accessory solutions (when necessary), MSDS, and instructions.