Standard Methods: 2320 B: Alkalinity by Titration

Summary
Analytes
Revisions
Data and Sites

Official Method Name

2320 B. Titration Method

Current Revision

Standard Methods 21st Edition (2005); Standard Methods Online

Media

WATER

Instrumentation

pH Meter

Method Subcategory

Physical

Method Source

Standard Methods

Citation

Standard Methods Online - Standard Methods for the Examination of Water and Wastewater

Brief Method Summary

Hydroxyl ions present in a sample as a result of dissociation or hydrolysis of solutes react with additions of standard acid. Alkalinity thus depends on the end-point pH used.

Scope and Application

Applicable to wastewater, surface waters, and drinking waters.

Applicable Concentration Range

Interferences

Soaps, oily matter, suspended solids, or precipitates may coat the glass electrode and cause a sluggish response. Allow additional time between titrant additions to let electrode come to equilibrium or clean the electrodes occasionally. Do not filter, dilute, concentrate, or alter sample.

Quality Control Requirements

See Section 2020 Quality Assurance/Quality Control.

Sample Handling

Collect samples in polyethylene or borosilicate glass bottles and store at a low temperature. Fill bottles completely and cap tightly. Because waste samples may be subject to microbial action and to loss or gain of CO2 or other gases when exposed to air, analyze samples without delay, preferably within 1 d. If biological activity is suspected analyze within 6 h. Avoid sample agitation and prolonged exposure to air.

Maximum Holding Time

14 days (regulatory)

Relative Cost

$51 to $200

Sample Preparation Methods

This method has 1 analyte associated with it.

Analyte	Detection Level	Bias	Precision	Pct False Positive	Pct False Negative	Spiking Level
Alkalinity(471-34-1) Alkalinity Calcium Carbonate Carbonic acid, calcium salt Marble	N/A	0% Bias (ML)	5.00 SD (ML)			120.00 %

Precision Descriptor Notes:	No general statement can be made about precision because of the great variation in sample characteristics. The precision of the titration is likely to be much greater than the uncertainties involved in sampling and sample handling before the analysis. Forty analysts in 17 laboratories analyzed synthetic samples containing increments of bicarbonate equivalent to 120 mg CaCO3/L. The titration procedure of 2320B.4.b was used, with an end point pH of 4.5. The standard deviation was 5 mg/L and the average bias (lower than the true value) was 9 mg/L. Sodium carbonate solutions equivalent to 80 and 65 mg CaCO3/L were analyzed by 12 laboratories according to the procedure of 2320B.4c. The standard deviations were 8 and 5 mg/L, respectively, with negligible bias. Four laboratories analyzed six samples having total alkalinities of about 1000 mg CaCO3/L and containing various ratios of carbonate/bicarbonate by the procedures of both 2320B.4a and c. The pooled standard deviation was 40 mg/L, with negligible difference between the procedures.
Detection Level Note:

Precision Descriptor Notes:

No general statement can be made about precision because of the great variation in sample characteristics. The precision of the titration is likely to be much greater than the uncertainties involved in sampling and sample handling before the analysis. Forty analysts in 17 laboratories analyzed synthetic samples containing increments of bicarbonate equivalent to 120 mg CaCO3/L. The titration procedure of 2320B.4.b was used, with an end point pH of 4.5. The standard deviation was 5 mg/L and the average bias (lower than the true value) was 9 mg/L. Sodium carbonate solutions equivalent to 80 and 65 mg CaCO3/L were analyzed by 12 laboratories according to the procedure of 2320B.4c. The standard deviations were 8 and 5 mg/L, respectively, with negligible bias. Four laboratories analyzed six samples having total alkalinities of about 1000 mg CaCO3/L and containing various ratios of carbonate/bicarbonate by the procedures of both 2320B.4a and c. The pooled standard deviation was 40 mg/L, with negligible difference between the procedures.

Detection Level Note:

Revision	PDF/Link
Standard Methods 21st Edition (2005); Standard Methods Online
Standard Methods Online
Standard Methods 18th, 19th, 20th ed.

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Standard Methods: 2320 B: Alkalinity by Titration

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