DR/4000 PROCEDURE OXYGEN SCAVENGERS. 4. Fill a second sample cell (the blank) with 25 ml of deionized water.

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1 DR/4000 PROCEDURE Method 8140 Iron Reduction Method f Oxygen Scavengers* µg/l carbohydrazide; µg/l DEHA; µg/l hydroquinone; µg/l iso-ascbic acid; µg/l methylethyl ketoxime (MEKO) Scope and Application: F testing residual crosion inhibits (oxygen scavengers) in boiler feed water condensate. * Adapted from Ishii and Koh, Bunseki Kagaku, (1979) HACH PROGRAM HACH PROGRAM: 2736 O Scav-Carbohy. ENTER 1. Press the soft key under HACH PROGRAM. Select the sted program number f the desired oxygen scavenger using the numeric keys. l Oxygen Scavenger Press: ENTER Program Number Carbohydrazide DEHA Hydoquinone Iso-Ascbic Acid Note: Samples must be analyzed immediately and cannot be sted f later analysis. Note: The Flow Cell and Sipper Modules can be used f this procedure. 2. The display will show: HACH PROGRAM: 2736 O Scav-Carbohy. HACH PROGRAM: 2736 O Scav-Carbohy. HACH PROGRAM: 2738 O Scav-DEHA HACH PROGRAM: 2738 O Scav-DEHA HACH PROGRAM: 2740 O Scav-Hydroquin HACH PROGRAM: 2740 O Scav-Hydroquin. HACH PROGRAM: 2742 O Scav-Iso-As. HACH PROGRAM: 2742 O Scav-Iso-As. HACH PROGRAM: 2744 O Scav-MEKO HACH PROGRAM: 2744 O Scav-MEKO 3. Fill a sample cell (the prepared sample) with 25 ml of sample. Note: Soak glassware with 1:1 Hydrochlic Acid Solution. Rinse several times with deionized water. These two steps will remove iron deposits which can cause slightly high results. Note: The sample temperature should be 25 ±3 C (77 ±5 F). Note: When determining those oxygen scavengers which react quickly with oxygen at room temperature, it may be necessary to stopper the cell containing the prepared sample in steps 3-8 to exclude air. 4. Fill a second sample cell (the blank) with 25 ml of deionized water. The wavelength (λ), 562 nm, is automatically selected. OxygenSca_PP_Other_IRD_Eng_4000.fm Page 1 of 6

2 , continued START TIMER 5. Add the contents of one DEHA Reagent 1 Powder Pillow to each sample cell. Swirl to mix. 6. Add exactly 0.5 ml of DEHA Reagent 2 Solution to each sample cell. Mix. Place both sample cells in the dark. Note: A purple col will develop if an oxygen scavenger is present. 7. Immediately press the soft key under START TIMER. A 10-minute reaction period ( a 2-minute period f hydroquinone) will begin. Note: Both sample cells must remain in the dark during the col reaction period. 8. When the timer beeps, place the blank into the cell holder. Close the light shield. Note: Temperature and reaction time affect the results. Be sure these facts are controlled as described. Note: Read the MEKO result at exactly 10 minutes f most accurate results. Page 2 of 6 OxygenSca_PP_Other_IRD_Eng_4000.fm

3 , continued ZERO 9. Press the soft key under ZERO. The display will show: 0 µg/l Carbo. 0 µg/l DEHA 0 µg/l Hydro. 0 µg/l ISA 0 µg/l MEKO Note: F alternate concentration units, press the soft key under OPTIONS. Then press the soft key under UNITS to scroll through the available options. Press ENTER to return to the read screen. 10. Immediately place the prepared sample into the cell holder. Close the light shield. Results in µg/l ( chosen units) will be displayed. Note: Repeat the above procedure, omitting the addition of DEHA Reagent 2 (Step 6), to determine the ferrous iron concentration in the sample. Crect f the ferrous iron concentration by pressing the soft keys under OPTION, (MORE) and then BLANK:OFF. Enter the reading attributed to the ferrous iron concentration and press ENTER. The net result is the actual oxygen scavenger concentration. Interferences Interfering Substance Bate (as Na 2 B 4 O 7 ) Cobalt Copper Ferrous Iron Hardness (as CaCO 3 ) Light Lignosulfonates Manganese Molybdenum Nickel Phosphate Phosphonates Sulfate Temperature Zinc Interference Level and Treatment Greater than 500 mg/l Greater than mg/l Greater than 8.0 mg/l All levels Greater than 1000 mg/l Light may interfere. Keep sample cells in the dark during col development. Greater than 0.05 mg/l Greater than 0.8 mg/l Greater than 80 mg/l Greater than 0.8 mg/l Greater than 10 mg/l Greater than 10 mg/l Greater than 1000 mg/l Sample temperatures below 22 C above 28 C (72 F 82 F) may affect test accuracy. Greater than 50 mg/l Substances which reduce ferric iron will interfere. Substances which complex iron strongly may also interfere. OxygenSca_PP_Other_IRD_Eng_4000.fm Page 3 of 6

4 , continued Sample Collection, Preservation and Stage Collect samples in clean, dry plastic glass containers. Avoid excessive agitation exposure to sunlight when sampling. Rinse the container several times with the sample. Allow the container to overflow and cap the container so there is no headspace above the sample. Rinse the sample cell several times with sample, then carefully fill to the 25-mL mark. Perfm the analysis immediately. Method Perfmance Precision Program Standard Level Confidence Limits µg/l µg/l µg/l µg/l µg/l µg/l µg/l µg/l µg/l µg/l F me infmation on determining precision data and method detection limits, refer to Section 1.5. Estimated Detection Limit Program F me infmation on derivation and use of Hach s estimated detection limit, see Section To determine a method detection limit (MDL) as defined by the 40 CFR part 136, appendix B, see Section Sensitivity Program Number: 2736 EDL µg/l µg/l µg/l µg/l µg/l Ption of Curve Abs Concentration Entire Range µg/l Program Number: 2738 Ption of Curve Abs Concentration Entire Range µg/l Program Number: 2740 Ption of Curve Abs Concentration Entire Range µg/l Page 4 of 6 OxygenSca_PP_Other_IRD_Eng_4000.fm

5 , continued Program Number: 2742 Ption of Curve Abs Concentration Entire Range µg/l Program Number: 2744 Ption of Curve Abs Concentration Abs µg/l 500 µg/l µg/l 900 µg/l µg/l See Section Sensitivity Explained f me infmation. Summary of Method Diethylhydroxylamine (DEHA) other oxygen scavengers present in the sample react with ferric iron in DEHA Reagent 2 Solution to produce ferrous ion in an amount equivalent to the DEHA concentration. This solution then reacts with DEHA 1 Reagent, which fms a purple col with ferrous iron. Safety Good safety habits and labaty techniques should be used throughout the procedure. Consult the Material Safety Data Sheet f infmation specific to the reagents used. F additional infmation, refer to Section 1. Pollution Prevention and Waste Management F infmation on pollution prevention and waste management, refer to Section 1. OxygenSca_PP_Other_IRD_Eng_4000.fm Page 5 of 6

6 , continued REQUIRED REAGENTS AND STANDARDS Quantity Required Description per test Unit Cat. No. Oxygen Scavenger Reagent Set (50 tests) Includes: (2) , (1) DEHA Reagent 1 Powder Pillows... 2 pillows /pkg DEHA Reagent 2 Solution... 1 ml ml Water, deionized ml... 4 liters REQUIRED EQUIPMENT AND SUPPLIES Dropper, 0.5 and 1.0-mL marks /pkg DR/ Inch Cell Adapter each OPTIONAL REAGENTS AND STANDARDS Hydrochlic Acid, 1:1 (6.0 N) ml OPTIONAL EQUIPMENT AND SUPPLIES Cylinder, graduated, polypropylene, 25-mL... each DR/4000 Carousel Module Kit... each DR/4000 Flow Cell Module Kit, 1-inch... each DR/4000 Flow Cell Module Kit, 1-cm... each DR/4000 Sipper Module Kit, 1-inch... each Stopper, hollow, poly, No /pkg Thermometer, -10 to 110 C... each FOR TECHNICAL ASSISTANCE, PRICE INFORMATION AND ORDERING: In the U.S.A. Call toll-free Outside the U.S.A. Contact the HACH office distribut serving you. On the Wldwide Web techhelp@hach.com HACH COMPANY WORLD HEADQUARTERS Telephone: (970) FAX: (970) Hach Company, All rights reserved. Printed in the U.S.A. 6/03 11ed Page 6 of 6 OxygenSca_PP_Other_IRD_Eng_4000.fm