In an LC–MS/MS method, structurally different cannabinoids can produce the same monitored ions. McRae and Melanson’s 17-analyte validation for cannabis and hemp illustrates why the chromatography deserves the same attention as the mass spectrometer.
The authors assessed cannabinoids with overlapping mass-spectrometric behavior and used retention time and chromatographic separation to distinguish compounds where transitions alone were insufficient. They validated liquid-solid extraction and a broad quantitative range for plant material, with sample dilution into an instrument calibration range of 10 to 10,000 ng/mL.
Request a mixed reference-standard chromatogram containing the relevant isomers. Compare it with the specimen chromatogram at the same retention-time scale and check how the lab handled an adjacent peak or a shoulder. A validated plant assay provides an example of this workflow. An oil, edible, or blood assay needs its own evidence for selectivity and performance in that matrix.
McRae and Melanson, Analytical and Bioanalytical Chemistry, 2020