AOAC Approves Method for Measuring THC in Hemp

An analytical method for detecting THC has been approved for use in hemp plants by AOAC International.

This validation from the lab standards organization will now allow labs to evaluate hemp for THC on a dry-weight basis, as required by the 2018 Farm Bill.

Testing the test

Thanks to that piece of legislation, hemp has been federally legal in the US since December 2018. But to be defined as hemp, and not the still federally illegal marijuana plant, the crop must contain no more than 0.3 percent THC.

To ensure this THC limit, crop samples must be regularly tested. But until now, no analytical method for doing so had been validated by AOAC.

“Until now, no globally recognized method for validating the potency of hemp was available to laboratories,” Scott Coates, AOAC’s Cannabis Analytical Science Program lead, said in a statement.

Developed by researchers from Eurofins Food Integrity & Innovation and the University of Chemistry and Technology, Prague, the new method uses a liquid chromatography–diode array detection technique and a mass spectrometer to detect both THC and its precursor molecule, THCA, individually, so their concentrations can be reported alone or as total THC.

The method was approved (with a few modifications) by AOAC in 2018 for use on cannabis plant materials, concentrates, and oils. Now, with another modification for sample dry weight determination, the method is also validated to analyse hemp.

“The performance of this method has been demonstrated thoroughly, and laboratories in the hemp industry can confidently implement this straightforward method for determination of total THC on a dry-weight basis,” said Melissa Phillips, a researcher at the US National Institute of Standards and Technology who chaired AOAC’s review panel.