By Kathryn L. Crepeau, Miranda S. Fram, and Noël Bush
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2004-5003
Sacramento, California 2004
An analytical method for the determination of the trihalomethane formation potential of water samples has been developed. The trihalomethane formation potential is measured by dosing samples with chlorine under specified conditions of pH, temperature, incubation time, darkness, and residual-free chlorine, and then analyzing the resulting trihalomethanes by purge and trap/gas chromatography equipped with an electron capture detector. Detailed explanations of the method and quality-control practices are provided. Method validation experiments showed that the trihalomethane formation potential varies as a function of time between sample collection and analysis, residual-free chlorine concentration, method of sample dilution, and the concentration of bromide in the sample.
Abstract
Introduction
Purpose and Scope
Acknowledgments
Method of Analysis of Trihalomethane Formation Potential
Scope and Application
Summary of Method
Equipment and Materials
Sample Collection and Filtration
Dosing and Quenching Procedure
Dose Calculation
Dosing
Incubating
Quenching and Acceptance Criteria
Standards
Primary Standard Solution
Calibration Standard Solutions
Surrogate Solution
Instrument Performance
Instrument Conditions
Calibration
Sample Analysis
Data Processing and Storage Procedures
EZChrom Software
Laboratory Information Management System
Method Validation
Method Precision
Effect of Sample Aging on Trihalomethane Formation Potential
Effect of Residual Chlorine Concentration on Trihalomethane Formation Potential
Effect of Dilution Method on Trihalomethane Formation Potential
Effect of Bromide Concentration on Trihalomethane Formation Potential
Quality-Control Practices
Analytical Sequence
Blanks
Calibration Verification Standards
Surrogate Standard
Retention Time and Peak Shape for Analytes
Duplication Samples
Instrument Maintenance
Summary
References Cited
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