Congratulations, your lab report just came back with a pass for pesticides. Time to celebrate, right? Well hold on just one minute; what does a pass really mean? In states with regulatory requirements for certain types of analytes, such as pesticides, a pass means that the value of the analyte was found by the testing […]
Congratulations, your lab report just came back with a pass for pesticides. Time to celebrate, right? Well hold on just one minute; what does a pass really mean?
In states with regulatory requirements for certain types of analytes, such as pesticides, a pass means that the value of the analyte was found by the testing lab to be less than the regulatory action level set forth by the state. Since regulatory requirement differ state to state, both 8.0 PPM (Parts Per Million) and 0.19 PPM of Eagle 20 could correctly be reported as a pass.
But wait, my report says “Non-Detect”, that means it is totally free of pesticides right?
It depends; when taken out of context, a non-detect doesn’t mean that the pesticide is not present. A non-detect means that the lab did not see the analyte or that the quantitative result was less than the laboratory’s limit of detection, LOQ. The labs ability to see an analyte, and its LOQ for a specific analyte, are based upon the method and instruments employed in the lab. The LOQ can also be influenced by regulatory requirements.
For this reason, the real question is: what does a non-detect and pass mean for your specific lab or state? For years, the only instrumentation used for pesticide screening of cannabis was Gas Chromatography. As the industry has advanced and states and local jurisdictions implement hard pass/fail limits, testing laboratories across the country are moving to more sensitive equipment. California is a prime example, as the state recently proposed new testing regulations (with standardized action levels) that will require laboratories to look lower than they ever have before. To understand what non-detect means for your specific lab report, you need to understand several terms:
Limit of Quantification (LOQ): the concentration at which quantitative results can be reported with a high degree of confidence.
Limit of Detection (LOD): the point at which analysis is just feasible, in other words the lab can see that what it’s looking for is there, but can’t accurately quantify.
Action Level/Reporting Limit: Level, typically determined by regulatory body, for monitoring a harmful or toxic substance – determines pass/fail on lab reports.
Validation: Labs can claim certain values for LOD and LOQ but have they been validated? Validation assesses the quality, reliability and consistency of analytical results; it is an integral part of any good analytical practice.
It’s important to ask your lab how it defines the above terms and what its limits are. These levels may all be set the same or they may be higher or lower than one another – it all depends on how your lab sets things up. Also ask why your lab chose a certain level/limit. Was it is based on the limits of the method/instrumentation or for some other reason?
Let’s finish with an analogy: two labs are counting people in a room filled with 9 people. Lab A has its LOQ set to 10 people – anything below that level is reported as no people detected, so it reports an ND. Lab B has its LOQ set to 1 person and it reports 9 people in the room. It all depends on how sensitive the counting equipment is and how a lab sets its levels.
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