Comparison of Grob Closed-Loop-Stripping Analysis (CLSA) to Other Trace Organic Methods

摘要

This paper presents a comparison of experimental results from the analysis of drinking water before and after water treatment using 1 million gallon per day (mgpd) granular activated carbon (GAC) contactors at the Cincinnati Water Works. The following methods of organic analysis were used: (1) Grob closed-loop stripping analysis (CLSA) using capillary GC/MS/DS, (2) Bellar purge and trap (P&T) using packed column GC/Hall/DS, ie, EPA Method 601, (3) Batch Liquid - Liquid Extraction (BLLE) using capillary GC/MS/DS, and (4) XAD-2 adsorption - ethyl ether elution (XAD-EEE) capillary GC/MS/DS. At least twice as many 'consent decree' organics (23) and the 'EPA Office of Drinking Water chemical indicators of industrial contamination' (18) were measured by Grob CLSA than by Bellar P&T, BLLE, and XAD-EEE analyses. Furthermore, Grob CLSA produced this superior analysis at a low cost-per-compound-analyzed figure. Of the 183 different organics which were measured by the four methods, six organics were detected by Bellar P&T, 107 by Grob CLSA, 90 by BLLE, and 58 by XAD-EEE analysis. A historical review of Grob CLSA is presented, as well as a brief review of current U.S. P&T methods. The design of a superior analytical scheme for the comprehensive analysis of purgeable organics in drinking water is indicated by the data. The combined use of Bellar P&T (EPA Methods 601 or 502), Grob CLSA, and BLLE analyses provides useful data on the level of many EPA regulated organics in drinking water.