LaMotte DPD-FAS User Manual

DPD-FAS TITRIMETRIC OUT FIT

MODEL DT · CODE 6806

QUANTITY CONTENTS CODE

250 mL Sodium Bicarbonate, 5.5% 6813-K 120 mL *Ferrous Ammonium Sulfate *6815-J 120 mL Glycine Solution 6811-J 100 g *DPD #1 Powder *6807-J 60 g *Potassium Iodide Crystals *6809-H 60 mL *Sulfuric Acid, 5% *6520-H 60 mL *Steadifac Reagent *6383WT-H 60 mL *Sodium Arsenite Solution *4128-H 30 mL Potassium Iodide, 0.5% 6810-G 20 g *EDTA Disodium Salt *6382-F 1 Deionized Water, 250 mL 5115PS-K 1 Deionized Water, 250 mL 5115PT-K 1 Spoon, 0.25g, plastic 0695 1 Spoon, 0.5 g, plastic 0698 1 Spoon, 1.0 g, plastic 0697 2 Flasks, Erlenmeyer, 250 mL 0433 1 Buret, 10 mL, funnel top 0426 1 Graduated Cylinder, 100 mL, glass 0419 1 Graduated Cylinder, 25 mL, glass 0417 1 Pipet, 0.5 mL, plastic w/20 mm cap 0369 4 Pipets, 1.0 mL, plastic 0354 1 Chemistry & Control of

Modern Chlorination

*WARNING: Reagents marked with a * are considered to be potential health hazards. To view or print a Material Safety Data Sheet (MSDS) for these reagents see MSDS CD or www.lamotte.com. To obtain a printed copy, contact LaMotte by email, phone or fax.

To order individual reagents or test kit components, use the specified code numbers.

1597

INTRODUCTION

The DPD-FAS (Diethyl-p-phenylene Diamine-Ferrous Ammonium Sulfate) titrimetric method of A. T. Palin, as described in Standard Methods APHA, AWWA , WPCF, 18th edition, provides a simple and accurate means of differentiating free and combined chlorine fractions, and while these determinations are of primary interest, an extension of the basic methods permits the determination of chlorine dioxide, chlorite, bromine, iodine and ozone.

The Model DT Outfit with special stabilized reagents and common glassware makes the method suitable for both laboratory and field use. The instructions are divided into 6 major sections (I-VI). Use the section that describes the sample being tested.

I. DPD Method for Free & Combined Chlorine II. Simplified Procedure for Free, Combined & Total Chlorine and

Nitrogen Trichloride

III.DPD Method for Chlorine Dioxide and Chlorite IV.DPD Method for Bromine V. DPD Method for Iodine VI.DPD Method for Ozone

DILUTED FAS TITRANT PREPARATION

A diluted stock of FAS titrant should be made fresh each day and any left at the end of the day should be discarded. Use the 1.0 mL pipet (0354) to measure and transfer 1.0 mL of *Ferrous Ammonium Sulfate (6815) to the 25 mL graduated cylinder (0417). Fill the graduated cylinder to the 25 mL line with deionized water (5115PS). Invert several times to mix. When a titration is made, pour the diluted FAS into the funnel top of the buret (0426) until it is full to the top. Adjust to the “0” line.

NOTE: The quantities given are suitable for concentrations of Total Chlorine up to 5 mg/L (5 ppm). Where the Total Chlorine exceeds 5 mg/L, use a smaller amount of the sample and dilute to 100 mL with distilled water, and use the usual amounts of reagents given for a 100 mL sample.

CONCENTRATION RANGE OF DPD PROCEDURES

The quantities of reagents that have been given for all of the tests described are suitable for concentrations of total available chlorine up to 5 mg/L (ppm). Where the total chlorine exceeds this figure, use a smaller sample and dilute with distilled water to a total volume of 100 mL.

PROCEDURES I. DPD METHOD FOR FREE & COMBINED CHLORINE

A. FREE CHLORINE

1. Use the 0.5 g spoon (0698) to add 0.5 g of *DPD #1 Powder (6807) to the 250 mL Erlenmeyer flask (0433).

2. Fill the 100 mL graduated cylinder (0419) to the 100 mL line with sample water. Pour into Erlenmeyer flask. Swirl until powder is dissolved. If free chlorine is present, solution will turn pink.

NOTE: In the presence of high monochloramine, add 10 drops of *Steadifac Reagent (6383WT) to prevent interference. This will give a Free Chlorine reading only. Discard and start again at Step 1A and continue to Step B5 for monochloramine, etc. Do not add *Steadifac Reagent if other forms of chlorine are to be determined.

3. Titrate rapidly with the diluted Ferrous Ammonium Sulfate Solution in the buret until the pink color disappears. Record buret reading as Reading A.

Reading A (mL) = (ppm) Free Chlorine

Retain sample and buret for testing Monochloramine.

B. MONOCHLORAMINE

4. Use the 1.0 g spoon (0697) to add one small *Potassium Iodide Crystal (6809) to the sample from Step 3. Swirl to mix. If monochloramine is present, solution will turn pink.

NOTE: If dichloramine concentration is expected to be high, substitute 2 drops Potassium Iodide, 0.5% (6810) for one *Potassium Iodide Crystal (6809) in Step 4.

5. Continue titrating with the diluted Ferrous Ammonium Sulfate Solution until the pink color disappears. Record buret reading as Reading B.

(Reading B – Reading A), mL = (ppm) Monochloramine

Retain sample and buret for testing Dichloramine.

C. DICHLORAMINE

6. Use the 1.0 g spoon (0697) to add 1.0 g of *Potassium Iodide Crystals (6809) to the sample from Step 5. Swirl until crystals are dissolved. Wait 2 minutes. If Dichloramine is present, solution will turn pink.

7. Continue titrating with the diluted Ferrous Ammonium Sulfate Solution until the pink color disappears. Record buret reading as Reading C.

Reading C (mL) = (ppm) Total Chlorine

(Reading C – Reading B), mL = (ppm) Dichloramine3

II. SIMPLIFIED PROCEDURE FOR FREE, COMBINED &

TOTAL CHLORINE AND NITROGEN TRICHLORIDE

A. FREE CHLORINE

1. Use the 0.5 g spoon (0698) to add 0.5 g of *DPD #1 Powder (6807) to the 250 mL Erlenmeyer flask (0433).

2. Fill the 100 mL graduated cylinder (0419) to the 100 mL line with sample water. Pour into Erlenmeyer flask. Swirl until powder is dissolved. If Free Available Chlorine is present, solution will turn pink.

3. Titrate rapidly with the diluted Ferrous Ammonium Sulfate Solution in the buret until the pink color disappears. Record buret reading as Reading A.

Reading A (mL) = (ppm) Free Chlorine

Retain sample and buret for testing Monochloramine.

B. TOTAL CHLORINE

4. Use the 0.5 g spoon (0698) to add 0.5 g of *DPD #1 Powder (6807) to a clean 250 mL Erlenmeyer flask (0433).

5. Use the 1.0 g spoon (0697) to add 1.0 g of *Potassium Iodide Crystals (6809) to the flask (0433).

6. Use the 100 mL graduated cylinder (0419) to add 100 mL of sample water to the flask (0433). Swirl until reagents are dissolved. Wait 2 minutes. If Total Chlorine is present, solution will turn pink.

7. Titrate rapidly with the diluted Ferrous Ammonium Sulfate Solution in the buret until the pink color disappears. Record buret reading as Reading B.

Reading B (mL) = (ppm) Total Chlorine

C. COMBINED CHLORINE

Reading B – Reading A = (ppm) Combined Chlorine

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