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EPA Method 305.1

EPA Method 305.1:
Acidity by Titration. Official Name: Acidity (Titrimetric)

Summary:
The pH of the sample is determined and a measured amount of standard acid is added, as needed, to lower the pH to 4 or less. Hydrogen peroxide is added, the solution boiled for several minutes, cooled, and titrated electrometrically with standard alkali to pH 8.2.

Scope:
This method is applicable to surface waters, sewages and industrial wastes, particularly mine drainage and receiving streams, and other waters containing ferrous iron or other polyvalent cations in a reduced state.

Citation:
Methods for the Chemical Analysis of Water and Wastes (MCAWW) (EPA/600/4-79/020)

Interferences:
Suspended matter present in the sample, or precipitates formed during the titration may cause a sluggish electrode response. This may be offset by allowing a 15-20 second pause between additions of titrant or by slow dropwise addition of titrant as the endpoint pH is approached.

QC Requirements:
None.

Maximum Holding Time:
14 days.

Media:
WATER

Subcategory:
Inorganic

Concentration:
Approximately 10 mg/L acidity to approximately 1000 mg/L as CaCO3, using a 50 mL sample.

Precision:
A multilaboratory study conducted by ASTM on 4 acid mine waters (with concentrations up to 2000 mg/L CaCO3) were used to determine precision.

Detection:
None.

Revision Number:
Issued 1971; Technical Revision 1974

Test Description:
Acidity -Titrimetric

Report Number:
600/4-79-020

Instrument used for this test:
Buret

View Actual EPA Method 305.1 (.pdf)

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