NEMI Method Summary

Method Summary Information

Method Number: 4500-CN-E Media: WATER
Revision: Standard Methods Online
Method Source: Standard Methods
Subcategory: INORGANIC Analytes in this method
Official Name: Cyanide: Colorimetric Method
Descriptive Name Colorimetric Method for Cyanide in Distillate
Source Info: Standard Methods Online is jointly produced by the American Public Health Association (APHA), the American Water Works Association (AWWA), and the Water Environment Federation (WEF).
These organizations may be contacted by phone for more information on Standard Methods Online:
APHA: (301) 893-1894
AWWA: (800) 926-7337, (1-303-794-7711, outside U.S. / Canada)
WEF: (800) 666-0206 (1-703-684-2452 outside U.S. / Canada)
Citation: Standard Methods Online
 
Brief Method
Summary:
 Cyanide in the alkaline distillate from preliminary treatment is converted to CNCl by reaction with chloramine-T at pH < 8 without hydrolyzing to CNO-. After reaction, CNCl forms a red-blue color on addition of a pyridine-barbituric acid reagent. Maximum color absorbance in aqueous solution is between 575 and 582 nm.
Scope And
Application:
 This method allows for determination of free cyanides in an alkaline distillate. The treatment and distillation preceding measurment determine what cyanide complexes are included in the measurement (complex cyanides release free cyanides that are measured with this method).
Applicable
Conc Range:
 0.02 - 0.2 mg-CN/L
Interferences: All known interferences are eliminated or reduced by distillation and interfence removal steps used during distillation. The distillation procedure 4500-CN- B lists known interferences and removal procedures; see also ASTM D2036 for information.
QC Requirements: See Standard Methods Section 1020.
Sample Handling: Add 0.1 g sodium arsenite in the presence of oxidizing agents. Add lead acetate or lead carbonate in the presence of sulfide. Filter sample before raising pH for stabilization. If samples cannot be analyzed immediately, add NaOH pellets or a strong NaOH solution to raise sample pH to 12 to 12.5. Store in a closed, dark bottle in a cool place.
Max Holding Time:
 24 hours after raising pH to > 12
Sample Prep Met Various (e.g., 4500-CN- B Distillation)
Relative Cost: Less than $50
URL to obtain ordering information for this method:
http://www.standardmethods.org/
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