"Minimum Level" or "ML" is the concentration at which the entire analytical system must give a recognizable signal and acceptable calibration point. The ML is the concentration in a sample that is equivalent to the concentration of the lowest calibration standard analyzed by a specific analytical procedure, assuming that all the method-specified sample weights, volumes, and processing steps have been followed. The analytical procedure used for determining the minimum level must be a procedure published by USEPA or a nationally recognized organization, including those methods in 40 CFR 136, 40 CFR 132, or Standard Methods, incorporated by reference in Section 301.106.

(Source: Amended at 47 Ill. Reg. 4415, effective March 23, 2023)