Hach DR2400 - Correcting for Volume Additions; Required Containers, Preservation Techniques and Holding Times

Chemical Analysis
Chemical Analysis
5940022ChemAnal.fm Page 29
3.1.3 Correcting for Volume Additions
If you use a large volume of preservative or neutralizer, you must account for
dilution by the acid added to preserve the sample, and/or the base used to
adjust the pH to the range of the procedure. Make this correction as follows:
1. Determine the volume of initial sample, the volume of acid and base added,
and the total final volume of the sample.
2. Divide the total volume by the initial volume.
3. Multiply the test result by this factor.
Example:
A one-liter sample was preserved with 2 mL of nitric acid. It was neutralized
with 5 mL of 5 N sodium hydroxide. The result of the analysis procedure was
10.00 mg/L. What is the volume correction factor and correct result?
1.
2.
3.
Hach 1:1 Nitric Acid Pillows contain 2.5 mL of acid: correct for this volume.
Total Volume 1000 mL 2 mL 5 mL+ + 1007 mL==
1007
1000
------------- 1.007 volume correction factor==
10.0 mg/L 1.007× 10.07 mg/L correct result==
Table 8 Required Containers, Preservation Techniques and Holding Times
1
Parameter No./Name Container
2
Preservation
3,4
Maximum Holding
Time
5
Table 1A - Bacterial Tests
1–4. Coliform, fecal and total P,G Cool, 4 °C, 0.008% Na
2
S
2
O
3
6 hours
5. Fecal streptococci P,G Cool, 4 °C, 0.008% Na
2
S
2
O
3
6 hours
Table 1A - Aquatic Toxicity Tests
6–10 Toxicity, acute and chronic P, G Cool, 4 °C 36 hours
Table 1B - Chemical Tests
1. Acidity P, G Cool, 4 °C 14 days
2. Alkalinity P, G Cool, 4 °C 14 days
4. Ammonia P, G Cool, 4 °C, H
2
SO
4
to pH<2 28 days
9. Biochemical oxygen demand (BOD) P, G Cool, 4 °C 48 hours
10. Boron P, PFTE or quartz HNO
3
to pH<2 6 months
11. Bromide P, G None required 28 days
14. Biochemical oxygen demand,
carbonaceous
P, G Cool, 4 °C 48 hours
15. Chemical oxygen demand P, G Cool, 4 °C, H
2
SO
4
to pH<2 28 days
16. Chloride P, G None required 28 days
17. Chlorine, total residual P, G None required Analyze immediately
21. Color P, G Cool, 4 °C 48 hours
23–24. Cyanide, total and amenable to
chlorination
P, G
Cool, 4 °C, NaOH to pH>12, 0.6
g ascorbic acid
6
14 days
7
25. Fluoride P None required 28 days