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3.1.3 Correcting for Volume Additions
Table 8 Required Containers, Preservation Techniques and Holding Times
Parameter No./Name
Table 1A - Bacterial Tests
1–4. Coliform, fecal and total
5. Fecal streptococci
Table 1A - Aquatic Toxicity Tests
6–10 Toxicity, acute and chronic
Table 1B - Chemical Tests
1. Acidity
2. Alkalinity
4. Ammonia
9. Biochemical oxygen demand (BOD)
10. Boron
11. Bromide
14. Biochemical oxygen demand,
carbonaceous
15. Chemical oxygen demand
16. Chloride
17. Chlorine, total residual
21. Color
23–24. Cyanide, total and amenable to
chlorination
25. Fluoride
5940022ChemAnal.fm
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.
Total Volume
=
1000 mL
2.
1007
------------ -
=
1.007
=
volume correction factor
1000
×
3.
10.0 mg/L
1.007
=
Hach 1:1 Nitric Acid Pillows contain 2.5 mL of acid: correct for this volume.
Container
P,G
P,G
P, G
P, G
P, G
P, G
P, G
P, PFTE or quartz
P, G
P, G
P, G
P, G
P, G
P, G
P, G
P
+
2 mL
+
5 mL
=
1007 mL
10.07 mg/L
=
correct result
2
Preservation
Cool, 4 °C, 0.008% Na
Cool, 4 °C, 0.008% Na
Cool, 4 °C
Cool, 4 °C
Cool, 4 °C
Cool, 4 °C, H
SO
2
4
Cool, 4 °C
HNO
to pH<2
3
None required
Cool, 4 °C
Cool, 4 °C, H
SO
2
4
None required
None required
Cool, 4 °C
Cool, 4 °C, NaOH to pH>12, 0.6
g ascorbic acid
None required
Chemical Analysis
1
Maximum Holding
3,4
5
Time
S
O
6 hours
2
2
3
S
O
6 hours
2
2
3
36 hours
14 days
14 days
to pH<2
28 days
48 hours
6 months
28 days
48 hours
to pH<2
28 days
28 days
Analyze immediately
48 hours
14 days
6
28 days
Chemical Analysis
7
Page 29
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