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5695230 
Journal Article 
USEPA Method Study 39, Method 504, 1,2-dibromoethane (EDB) and 1 ,2-dibromo-3-chloropropane (DBCP) in Water by Microextraction and Gas Chromatography 
Edgell, KW 
1988 
An interlaboratory collaborative study was conducted to determine the precision and bias (recovery) of Method 504 for the analysis of two semi-volatile organic compounds in groundwater. Method 504 is entitled, ' 1,2-Dibromoethane and 1,2 ,-Dibromo-3-chloropropane in Water by Microextraction and Gas Chromatography ', and includes instructions for quality control, sample preparation and analyses of samples by gas chromatography. A detailed investigation of the number of outliers is a good measurement of the ruggedness of the method. In this study, 15% of the submitted data points were rejected as outliers. The laboratory ranking test, associated with systematic errors, represented 67% of the total rejected data while the individual outlier test accounted for the remaining 33 %. One laboratory accounted for 41% of the total outliers while 7 laboratories had no outliers for 1,2-dibromoethane and 8 laboratories had no outliers for 1,2-dibromo-3-chloropropane. The groundwater produced no apparent matrix effect on the number of outliers (7.1% outliers in reagent water and 7.9% outliers in groundwater). The relatively low percentage of outlier data indicated that the method is rugged. The recovery of the method was obtained by comparing the mean values from the study to the true value concentrations. Recoveries of 107% and 108% for reagent water and groundwater were found for 1,2-dibromoethane. For 1,2-dibromo-3-chloropropane recoveries of 99% and 97% were found for reagent water and groundwater, respectively. The overall standard deviation expressed as the percent relative standard deviation (%RSD) was 8% for 1,2-dibromoethane in reagent water and groundwater respectively. The %RSD was 14% and 16% for 1,2-dibromo-3-chloropropane in reagent water and groundwater respectively. The single-analyst standard deviation expressed as the percent relative standard deviation (%RSD-SA) was 4% and 5% for 1,2-dibromoethane in reagent water and groundwater and 7% and 8% for 1,2-dibromo-3-chloropropane in reagent water and groundwater respectively. (Lantz-PTT) 
Water Resources Abstracts; Water analysis; Testing procedures; Pollutant identification; Organic compounds; Chemical analysis; Volatile organic compounds; Dibromoethane; Chloropropane; Gas chromatography; Statistical analysis; Quality control