Mt street res


A Simple Spectrophotometric Method for the Determination of THMs in Drinking Water

American Water Works Association Research Foundation, 9/1/88-3/31/90

Students: Pamela Pierce, Kristin Coombs, Maureen Kearney

This research project was aimed at developing a rapid spectrophotometric test for trihalomethanes (THMs) based on the Fujiwara reaction using pyridine or its derivatives. A visible-wavelength spectrophotometer, some standard laboratory glassware, chemical reagents, and (for the purge-and-trap [P&T] methods) a tank of nitrogen are all that is necessary.

Proposal, Plans and Reports

Project Data


Conference presentations based on this work

Theses/Dissertations based on this work


Additional Background: Two different types of colorimetric reactions (1-phase and 2-phase) and two types of sample extraction methods were investigated. Of the two reaction conditions, the 1-phase reaction gave results that were more reproducible than the 2-phase reaction. Sample extraction and concentration were accomplished by solvent extraction or by purge-and-trap methods. Although both can achieve the desired level of analyte concentration, the purge and trap was much faster and less complicated. Accordingly, the recommended method incorporates purge and trap along with simultaneous 1-phase reaction in alkaline pyridine. Use of a 15-minute purge cycle allows one to obtain results within 20 minutes from the time of sample collection and quench.
The purge-and-trap, 1-phase method was optimized and evaluated for analysis of low-bromide waters. Method detection limit was determined to be 2 or 8 /ig/L as chloroform when a 125-mL sample is used and 12 fig/L for a 30-mL sample. Field evaluations showed good reproducibility and good agreement with total trihalomethane (TTHM) analysis by the standard solvent-extraction gas chromatographic method. Studies conducted on an in-line filtration pilot plant demonstrated the utility of the alkaline pyridine tests for engineering assessment of treatment processes in the field. (acc# 5-20245).



Return to Dave Reckhow's home page.