Hardness, Total Ultra Low RangeDR 1900 Analytical Procedure AP-67/1900

SPECIFICATIONSMethod: Spectrophotometric (DR 1900)Range: 13 to 1000 3 ug/L hardness, as CaCO3Testing Time: 5 minutes

DESCRIPTIONThe Ultra Low Range (ULR) Hardness procedure for the Nalco DR 1900 spectrophotometer permits analysis of high purity waters (high pressure boiler feedwaters, RO permeate, demineralizer trains, etc.), without the need for expensive AA/ICP instrumentation. Calcium and magnesium combine equivalently with the Chlorophosphonazo Indica-tor to form a colored complex which absorbs light very strongly at 669 nm. One drop of the CDTA reagent breaks up this complex, and the resultant decrease in color is proportional to the amount of calcium and magnesium (as CaCO3) in the sample.

ORDERING INFORMATIONOrder all replacement parts and reagents by their part numbers. To be sure this product is compatible with your treatment program, contact your local Nalco Sales Engineer. To place your order, please contact your local customer service department.

REPLACEMENT PARTS AND REAGENTSRequired PartsDescription Part No. Nalco DR 1900 Spectrophotometer 400-P1900.88CDTA Reagent, 10 mL 460-S0471.70Chlorophosphonazo Indicator Pillows, 100/pkg 460-S0472.87Sample cells, 1 cm x 1 in dual pathlength 500-P2531.88Adapter for dual pathlength cells 500-P2532.88

Nalco DR 1900 Spectrophotometer

INTERFERENCESInterference studies were conducted at various hardness levels between 0 and 500 ug/L (as CaCO3). Various cations and anions were added in a range appropriate to ultra pure water applications. Ion in concentrations results in the following effects:Aluminum > 150 ug/L causes lower resultsCopper > 250 ug/L causes higher resultsSodium > 79 mg/L causes low resultsSilicon > 1000 ug/L causes high resultsPotassium < 1000 ug/L no interferenceAmmonium < 1000 ug/L no interferenceFormaldehyde < 47 mg/L no interference

SAFETY PRECAUTIONSRefer to Safety Data Sheet (SDS) for specific reagent personal safety and disposal information.

SUPPORTIf you have any questions regarding this procedure, please contact your Nalco Sales Engineer. In North America you can also contact the Nalco Equipment Help Desk at 630-305-CHEM.

Notes: A small amount of solution may remain in the pillow. This will not affect results.One mL of Chlorophos-phonazo Solution may be used instead of the solution pillow.

TOTAL ULTRA LOW RANGE HARDNESS DR 1900 PROCEDURE

Special Note: Do not use glass containers.

Rinse a plastic sample cell and the cap three times with the water to be tested. Do not allow the underside of the cap to come in contact with surfaces that may contaminate it.

Note: Care must be taken to avoid contaminating samples and reagents.

Fill the plastic sample cell to the 25-mL mark with sample.

Add the contents of one Chlorophosphonazo Solution Pillow (460-S0472.87) to the sample cell.

Select: Stored Programs

Select stored program 228 Hardness, Tot. ULR

Select: Start

1

Stored Programs

2 3 4

SAMPLINGDo not use glass containers. Glass can contaminate high-purity water significantly. For this reason, use only clean plastic bottles or jars. Rinse the container at least three times with the sample before capturing the final sample. Seal the container during trans-port to minimize contamination. Ideally, the sample should be collected directly into the sample cell used for the analysis.

Cap the cell and swirl to mix. (This is the blank.)

Place the blank into the cell holder.

Select: ZERO.The display will show: 0 ug/L CaCO3

Remove the cell from the instrument. Add one drop of CDTA Reagent (460-SO471.70) for Ultra Low Range Hardness.

Note: Complete Steps 9-11 within 1-2 minutes

Cap the cell and swirl to mix. Place the cell into the cell holder.

Select: READ.The result in ug/L as CaCO3 will be displayed.

85

9

6 7

Zero

11

Read

10

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