A Reporting Limit (RL or RDL) is the limit of detection for a specific target analyte for a specific sample after any adjustments have been made for dilutions or percent moisture. Some state regulatory programs require a laboratory to prove it can reliably “see” down to its RL by setting the RL at the lowest point on the calibration curve.
In contrast, the Method Detection Limit or MDL is lower than the RL (often much lower) and is a statistical calculation. Since the MDL is below the point of calibration, results reported down to the MDL are not reliable and must be qualified as estimated values and, as such, carry a “J” qualifier designation.