187

Method 8143COPPER (0 to 210.0 g/L) For water, wastewater and seawaterPorphyrin Method*

1. Enter the stored program number for copper (Cu), porphyrin method.

Press: PRGMThe display will show:

PRGM ?

2. Press: 22 ENTERThe display will show g/L, Cu and the ZERO icon.Note: Total copper determination needs a prior digestion; use either the Digesdahl or vigorous digestion (Section 2).

3. Fill two sample cells with 10 mL of sample.Note: Wash all glassware with detergent. Rinse with tap water. Rinse again with Nitric Acid Solution, 1:1. Rinse a third time with copper-free, deionized water.

4. Add the contents of one Copper Masking Reagent Powder Pillow to one of the sample cells (the blank). Swirl to dissolve.Note: The other sample cell is the prepared sample.

5. Add the contents of one Porphyrin 1 Reagent Powder Pillow to each sample cell. Swirl to dissolve the powder.

6. Add the contents of one Porphyrin 2 Reagent Powder Pillow to each sample cell. Swirl to dissolve the powder.Note: The yellow color will turn blue momentarily. If any copper is present, the yellow color will return.

7. Press: TIMER ENTER

A three-minute reaction period will begin.

8. After the timer beeps, place the blank into the cell holder. Tightly cover the sample cell with the instrument cap.

* Adapted from Ishii and Koh, Bunseki Kagaku, 28 473 (1979)

188

Sampling and StorageCollect samples in acid-washed plastic bottles. To preserve, adjust the pH to 2 or less with nitric acid (about 5 mL per liter). Store preserved samples up to six months at room temperature.

Before testing, adjust the pH of the sample to between 2 and 6. If the sample is too acidic, adjust the pH with 5.0 N Sodium Hydroxide Standard Solution. Correct test results for volume additions; see Correction for Volume Additions in Section 1 for more information.

9. Press: ZEROThe cursor will move to the right, then the display will show:

0.0 g/L Cu

10. Place the prepared sample into the cell holder. Tightly cover the sample cell with the instrument cap.Note: If samples with high levels of metal are analyzed, a slight metallic deposit or yellow buildup may appear on the sample cell wall. Remove by rinsing with nitric acid. Dilute a fresh sample and repeat the test. Multiply the result by the dilution factor; see Section 1.

11. Press: READThe cursor will move to the right, then the result in g/L copper (Cu) will be displayed.Note: Standard Adjust may be performed using a prepared standard (see Standard Adjust in Section 1).

.

COPPER, continued

189

Accuracy CheckStandard Additions Method

a) Fill six (3 pairs) 25-mL graduated mixing cylinders with 25 mL of sample. Properly mark each pair of cylinders as sample and blank.

b) Using a TenSette Pipet, add 0.1 mL of Copper Standard Solution, 10.0 mg/L Cu, to two of the cylinders. Add 0.2 mL of standard to two more of the cylinders. Add 0.3 mL of standard to the other two cylinders, making a total of six samples (2 for each volume of standard).

c) Analyze the samples as described above. The copper concentration reading should increase by 40 g/L for each 0.1 mL of standard added.

d) If these increases do not occur, see Standard Additions in Section 1 for more information.

Standard Solution MethodTo assure the accuracy of the test, prepare a 100 g/L copper standard:

a) Pipet 1.00 mL of Copper Standard Solution, 10.0 mg/L Cu, into a 100-mL volumetric flask.

b) Dilute to volume with copper-free, reagent-grade water.c) Use this standard in place of the sample in the procedure.

The reading should be 100 g/L Cu.

d) Prepare this solution daily.Method Performance

PrecisionIn a single laboratory, using a standard solution of 100 g/L copper and two representative lots of reagent with the instrument, a single operator obtained a standard deviation of 3.4 g/L copper.

Estimated Detection LimitThe estimated detection limit for program 22 is 5.4 g/L Cu. For more information on the estimated detection limit, see Section 1.

COPPER, continued

190

InterferencesThe following may interfere when present in concentrations exceeding those listed below:

Chelating agents, such as EDTA, interfere at all levels unless either the Digesdahl or vigorous digestion (Section 2) is performed.

Highly buffered samples or extreme sample pH may exceed the buffering capacity of the reagents and require sample pretreatment: see pH Interferences in Section 1.

Summary of MethodThe porphyrin method is very sensitive to trace amounts of free copper. Due to the sensitivity of the method, a masking agent is used to prepare a blank for each sample. The method is free from most interferences and does not require any sample extraction or preconcentration. Interferences from other metals are eliminated by the copper masking reagent. The porphyrin indicator forms an intense, yellow-colored complex proportional to any free copper present in the sample. Total copper may be determined if a digestion is performed prior to analysis.

Substance Concentration Substance Concentration

Aluminum 60 mg/L Magnesium 10,000 mg/LCadmium 10 mg/L Manganese 140 mg/LCalcium 15,000 mg/L Mercury 3 mg/LChloride 90,000 mg/L Molybdenum 11 mg/LChromium (Cr6+) 110 mg/L Nickel 60 mg/LCobalt 100 mg/L Potassium 60,000 mg/LFluoride 30,000 mg/L Sodium 90,000 mg/LIron (Fe2+) 6 mg/L Zinc 9 mg/LLead 3 mg/L

COPPER, continued

191

REQUIRED REAGENTS Cat. No.

Copper Reagent Set, 10-mL samples (100 tests) ..........................................................26033-00 Includes: (1) 26034-49, (2) 26035-49, (2) 26036-49

Quantity RequiredDescription Per Test Unit Cat. No.Copper Masking Reagent Powder Pillows.............. 1 pillow................100/pkg ..........26034-49Porphyrin 1 Reagent Powder Pillows..................... 2 pillows...............100/pkg ..........26035-49Porphyrin 2 Reagent Powder Pillows..................... 2 pillows...............100/pkg ..........26036-49REQUIRED APPARATUSSample Cell, 10-20-25 mL, w/ caps..............................2 .........................6/pkg ..........24019-06OPTIONAL REAGENTSCopper Standard Solution, 10 mg/L Cu ................................................ 100 mL ..............128-42Hydrochloric Acid Solution, 1:1 (6 N).................................................. 500 mL ..............884-49Nitric Acid, ACS................................................................................... 500 mL ..............152-49Nitric Acid Solution, 1:1 ....................................................................... 500 mL ............2540-49Sodium Hydroxide Standard Solution, 5 N.................................................. 1 L ............2450-53Water, deionized ........................................................................................... 4 L ..............272-56OPTIONAL APPARATUSBeaker, 100 mL ...........................................................................................each ...........500-42HCylinder, mixing, graduated, 25 mL ...........................................................each ..........20886-40Flask, volumetric, Class A, 100 mL............................................................each ..........14574-42Hot Plate, 7 x 7 inches, 120 V.....................................................................each ..........23441-00Hot Plate, 7 x 7 inches, 240 V.....................................................................each ..........23441-02pH Paper, 1 to 11 pH units ................................................................5 rolls/pkg ..............391-33pH Meter, sension1, portable, with electrode...........................................each ..........51700-10Pipet, Mohr, 5 mL .......................................................................................each ..........20934-37Pipet, TenSette, 0.1 to 1.0 mL .....................................................................each ..........19700-01Pipet Tips, for 19700-01..........................................................................50/pkg ..........21856-96Pipet Tips, for 19700-01......................................................................1000/pkg ..........21856-28Pipet, volumetric, 1.0 mL, Class A .............................................................each ..........14515-35Pipet Filler, safety bulb ...............................................................................each ..........14651-00Watch Glass, Pyrex, 100 mL.....................................................................each ..............578-70

For Technical Assistance, Price and OrderingIn the U.S.A.Call 800-227-4224Outside the U.S.A.Contact the Hach office or distributor serving you.

COPPER, continued