Collaborative Study of the Toxicity Characteristic Leaching Procedure (TCLP)

The United States Environmental Protection Agency has developed a new procedure, the Toxicity Characteristic Leaching Procedure (TCLP), to more effectively simulate the leaching of hazardous materials from waste disposed in an unsecured landfill. The procedure involves (1) an 18-h extraction of a sample with sodium acetate solution and (2) the subsequent analysis of the leachate for metals, pesticides, semivolatile organics, and volatile organic compounds. To validate the method for all but the volatile organic analytes, three waste samples at two different pH levels were sent to 23 different volunteer government and commercial laboratories for extraction and analysis. For validation of the TCLP procedure involving determination of volatile organic compounds, two fortified waste samples were distributed to each participating laboratory. The results and statistical analysis of this collaborative test are presented and discussed. These results indicate that the TCLP can be applied consistently by a diverse group of organizations for the analyses considered in this study.