There is no question that the demand for cannabis is surging. According to recent research, the global legal marijuana market size was valued at USD 9.1 billion in 2020 and is expected to expand at a compound annual growth rate (CAGR) of 26.7% from 2021 to 2028.1

The new question is how to ensure safety of the supply while demand accelerates. As a consumer product, cannabis and hemp products require multiple safety tests to meet regulatory requirements. Among the necessary tests is analysis of heavy metals, which may be toxic if ingested or inhaled. However, due to a lack of federal oversight, states and provinces have set their own regulations, making it difficult to guarantee consistent product quality.

In response to this challenge, Agilent and CEM (a supplier of microwave digestion systems and methods), teamed up to create an accurate, standardized analytical method for heavy metal testing in cannabis. This method uses ICP-MS (Inductively Coupled Plasma Mass Spectrometry) for the quantification of arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb). Other elements can be added to the method following appropriate validation.

In a recent announcement, AOAC International announced that it has granted first action approval for this method in the determination of heavy metals in cannabis and hemp products. That means manufacturers can now implement a standardized, accurate methodology to routinely test for these metals in ingredients and final products. And that is a major step forward in ensuring safety in this fast-growing market.

The new method passed rigorous review by a panel of cannabis industry experts and is the first method approved by AOAC for this use. The accuracy and precision of the ICP-MS-based method met the AOAC Standard Method Performance Requirements for Determination of Heavy Metals in a Variety of Cannabis and Cannabis-Derived Products (SMPR 2020.001) for all four elements of interest.

A Closer Look at the Testing Method

The heavy metal testing method approved by AOAC specifies microwave acid digestion of homogenized cannabis or hemp samples, followed by quantitative analysis by ICP-MS. The method was developed in accordance with the AOAC SMPR requirements using an Agilent 7850 ICP-MS.