Method 325.1

Chloride (Colorimetric, Automated Ferricyanide AAI)

This method is for the determination of chloride from drinking, surface, and saline waters, domestic and industrial wastes.  Thiocyanate ion (SCN) is liberated from mercuric thiocyanate through sequestration of mercury by chloride ion to form un-ionized mercuric chloride.  In the presence of ferric ion, the liberated SCN forms highly colored ferric thiocyanate in concentration proportional to the original chloride concentration.  The colored ferric thiocyanate is analyzed using by colorimetry using an automated ferricyande AAI instrument.

The applicable range is 1 to 250 mg/L. This range may be extended by sample dilution. 

(EPA: Office of Water)


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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   28 days from sample collection to analysis.
Preservatives:   None noted in method.
Required Preps:   125 mL HDPE or amber glass bottle.
Collection Method:   Grab sampling
Analytical Methodology:   Automated spectrophotometer
Documentation:   325.1

Analyte List*

Analyte Formula CAS Number Detection Limit

* 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.