EPA-NERL: 325.1: Chloride by Automated Colorimetry

Summary
Analytes
Revision
Data and Sites

Official Method Name

Chloride (Colorimetric, Automated Ferricyanide AI)

Current Revision

Issued 1971

Media

WATER

Instrumentation

Automated Spectrophotometer

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

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 a highly colored ferric thiocyanate in concentration proportional to the original chloride concentration. Measurements of the colored complex are made using an automated spectrophotometer.

Scope and Application

This automated method determines chloride in drinking, surface, and saline waters; domestic and industrial wastes.

Applicable Concentration Range

1 - 250 mg/L

Interferences

No significant interferences.

Quality Control Requirements

None.

Sample Handling

No special requirements.

Maximum Holding Time

28 days (MCAWW, Table 1).

Relative Cost

Less than $50

Sample Preparation Methods

This method has 1 analyte associated with it.

Analyte	Detection Level	Bias	Precision	Pct False Positive	Pct False Negative	Spiking Level
Chloride(16887-00-6) Chloride Chloride ion	1.000 mg/L	101% Rec (ML)	4.00 % RSD (ML)			50.00 mg/L

Precision Descriptor Notes:	Precision and accuracy values were calculated using interlaboratory data from EPA-managed Water Pollution (WP) performance evaluation studies.
Detection Level Note:

Revision	PDF/Link
Issued 1971

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EPA-NERL: 325.1: Chloride by Automated Colorimetry

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