Not detected (ND)
NDThis laboratory result indicates that an analyte was not found above the method's detection or reporting threshold, rather than that the substance is entirely absent.
Every analytical method has a floor below which it cannot see, defined by its limit of detection and limit of quantitation. When a measured signal falls beneath that floor, the laboratory reports the analyte as absent at the level of the test, often with the threshold printed alongside. The result therefore describes the sensitivity of the method as much as the contents of the sample.
On a certificate of analysis such entries appear as an abbreviation or a symbol in the result column, and the meaning depends on the number in the limit column next to it. For THC, retailers commonly express the same finding as 0.0% THC, which is the wording used throughout this index; either way, a reader should look for the detection limit to understand how sensitive the test was. Two products with the same result can have been tested to different limits.