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5333918 
Technical Report 
EPA METHOD STUDY 32: METHOD 450.1 -TOTAL ORGANIC HALIDES (TOX) (PROJECT SUMMARY) 
Tate, CH; Chow, BM; Et al 
1986 
OH 
English 
HMTC EPA interim method 450.1 for measuring total organic halides (TOX) is evaluated. TOX are measured by adsorbing TOX onto activated charcoal. The columns of activated charcoal are pyrolzed, converting the halides to titratable species which are measured microcoulometrically. The method is evaluated with a computerized package call the Interlaboratory Method Validation Study (IMVS) which includes outlier tests, estimation of mean recovery as a measure of bias, estimation of single-analyst and overall precision, and a test for the effects of water type of these statistical estimates. The IMVS indicates that Method 450.1 is capable of measuring TOX in drinking, ground, and surface waters. The method bias and precision are acceptable and there are no significant matrix effects with drinking, ground, or surface water. It is recommended that the "interim" designation be removed from the current title of the method. Suggestions to ensure more consistent performance of the method and to avoid sample contamination are included. Additional research is needed on the performance of the method when analyzing chlorinated drinking water supplies.