Method SM 2320B


This method is for the determination of alkalinity in wastewater, surface water and drinking water. Soaps, oily matter, suspended solids or precipitates in the sample can coat the glass electrode and cause a sluggish response. The sample should not be filtered, diluted, concentrated or altered after collection. Alkalinity of a water is its acid-neutralizing capacity and is the sum of all the titratable bases. Alkalinity is a measure of an aggregate property of water and can be interpreted in terms of specific substances only when the chemical composition of the sample is known. Because the alkalinity of many surface waters is primarily a function of carbonate, bicarbonate, and hydroxide content, it is taken as an indication of the concentration of these constitutents. 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. The construction of a titration curve by recording sample pH after successive small measured additions of titrant permits identification of inflection points and buffering capacity, if any, and allows the alkalinity to be determined with respect to any pH of interest. The method recommends to analyze samples without delay and preferably within one day. If biological activity is suspected, the sample should be analyzed within six hours of sample collection. Regulatory requirements are to analyze the sample within 14 days of sample collection.

(Standard Methods)


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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   14 days from sample collection to analysis for regulatory purposes.
Preservatives:   Store at a low temperature (4°C ± 2)
Required Preps:   250 mL polyethylene or borosilicate glass bottle
Collection Method:   Grab sampling
Analytical Methodology:   Electrometric Titration, pH Meter, or Color Indicator.
Documentation:   SM 2320B

Analyte List*

Analyte Formula CAS Number Detection Limit
Alkalinity, Total

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.