I sent a solid sample to the laboratory for TCLP and they sent back results in units of milligrams per liter (mg/L). How can a solid sample have a concentration in terms of its volume in liters?
The TCLP Method 1311 is a leaching procedure that is used to evaluate a sample to see if it exhibits the RCRA characteristic of toxicity, as defined in 40 CFR §261.24. As part of the TCLP process, the sample is leached with a specific acidic solution and the resulting liquid leachate is subsequently analyzed. Since the leachate is a liquid, the results from its analysis are reported in units of milligrams per liter, even though the original sample was a solid.
Because the regulatory limits used in the toxicity characteristic apply to the leachate, the units are also expressed in units of milligrams per liter (mg/L). As a result, you do not need to convert the units for these results and you can simply compare the results to the numerical limits for the toxicity characteristic shown in 40 CFR §261.24.