Hach DR2400 - Page 252

Copper
Copper
Page 4 of 6
Copper_AVPP_Other_BIC_Eng_Ody.fm
Sample Collection, Storage and Preservation
Collect samples in acid-cleaned glass or plastic containers. Adjust the pH to 2 or
less with concentrated nitric acid (about 2 mL per liter) (Cat. No. 2540-49). Store
preserved samples up to six months at room temperature. Before analysis, adjust
the pH to 4–6 with 8 N Potassium Hydroxide (Cat. No. 282-32). Do not exceed
pH 6, as copper may precipitate. Correct the test result for volume additions; see
Section 3.1.3 Correcting for Volume Additions on page 29. If only dissolved copper
is to be determined, filter the sample before acid addition.
Accuracy Check
Standard Additions Method (Sample Spike)
1. After reading test results, leave the sample cell (unspiked sample) in the
instrument.
2. Touch
Options. Touch Standard Additions. A summary of the standard
additions procedure will appear.
3. Touch
OK to accept the default values for standard concentration, sample
volume, and spike volumes. Touch
Edit to change these values. After values
are accepted, the unspiked sample reading will appear in the top row. See
Standard Additions in the instrument manual for more information.
4. Snap the neck off of a Copper Voluette
®
Ampule Standard, 12.5-mg/L Cu.
5. Prepare a 0.1 mL sample spike by adding 0.1 mL of standard to the unspiked
sample. Touch the timer icon. After the timer beeps, read the result.
6. Prepare a 0.2 mL sample spike by adding 0.1 mL of standard to the 0.1 mL
sample spike. Touch the timer icon. After the timer beeps, read the result.
7. Prepare a 0.3 mL sample spike by adding 0.1 mL of standard to the 0.2 mL
sample spike. Touch the timer icon. After the timer beeps, read the result.
Each addition should reflect approximately 100% recovery.
Note: For AccuVac Ampuls, fill three mixing cylinders (Cat. No. 1896-41) with 50-mL of sample and
spike with 0.2 mL, 0.4 mL, and 0.6 mL of Copper Voluette Ampule Standard, 75-mg/L Cu.
Transfer 40 mL from each of the three mixing cylinders to three 50-mL beakers
(Cat. No. 500-41H). Analyze each standard addition sample as described in the procedure
Table 2 Interfering Substances and Suggested Treatments for AccuVac
®
Ampuls
Interfering Substance Interference Levels and Treatments
Acidity
If the sample is extremely acidic (pH 2 or less) a precipitate may form. Add 8 N Potassium
Hydroxide Standard Solution (Cat. No. 282-32) drop-wise until sample pH is above 4. Continue
with step 2.
Aluminum, Al
3+
Reagents accommodate high levels.
Cyanide, CN
–
Prevents full color development. Add 0.5 mL of formaldehyde (Cat. No. 2059-32) to a 25-mL
sample before using CuVer 2 Reagent AccuVac Ampul. Wait 4 minutes before taking the
reading. Multiply the test results by 1.02 to correct for sample dilution by the formaldehyde.
Hardness Reagents accommodate high levels.
Iron, Fe
3+
Reagents accommodate high levels.
Silver, Ag
+
If a turbidity remains and turns black, silver interference is likely. Add 10 drops of saturated
Potassium Chloride Solution (Cat. No. 765-42) to 75 mL of sample, followed by filtering through
a fine or highly retentive filter. Use the filtered sample in the procedure.