EPA-NERL: 305.1:  Acidity by Titration

  • Summary
  • Analytes
  • Revision
  • Data and Sites
Official Method Name
Acidity (Titrimetric)
Current Revision
Issued 1971; Technical Revision 1974
Media
WATER
Instrumentation
Titration
Method Subcategory
Inorganic
Method Source
  EPA-NERL
Citation
  Methods for the Chemical Analysis of Water and Wastes (MCAWW) (EPA/600/4-79/020)
Brief Method 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 and Application
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.
Applicable Concentration Range
Approximately 10 mg/L acidity to approximately 1000 mg/L as CaCO3, using a 50 mL sample.
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.
Quality Control Requirements
None.
Sample Handling
Refrigeration at 4oC is recommended.
Maximum Holding Time
14 days.
Relative Cost
Less than $50
Sample Preparation Methods