Enzyme Immunoassay: A Cost-Effective Way to Measure Aflatoxin B1 in Cannabis

Written by Lydia Kariuki

With the rapid growth of the legal cannabis market, the need to ensure product safety using cost-effective methods has become imperative. To date, there is still a lack standardization of methods used to analyze contaminants in cannabis. Consequently, such variances have contributed to the rampant infiltration of contaminated THC and CBD products in the legal market. This poses a serious threat to the safety of consumers in the medical, recreational, and nutraceutical sectors. [1]

Toxic contaminants that may be present in cannabis include: heavy metals [2], pesticides, and mycotoxins such as aflatoxins [3].

Aflatoxins (AFs) are widespread and may cause carcinogenic, genotoxic, or immunosuppressive effects in humans. Aflatoxin B1 (AFB1) has been detected in cannabis and linked to the development of hepatocellular carcinoma and malnutrition [4].

Immunoassays are common analytical methods used in the food industry. As much as they are cost effective and convenient, they have not been used widely in the cannabis industry. Immunoassays test the presence of a compound by recording the response to an antibody or antigen.

Researchers from the University of Turin (Italy) adapted an immunoassay technique used to measure the amount of aflatoxin B1 in cannabis inflorescences.


Fourteen samples of cannabis inflorescence (flower) were obtained from random retail outlets in Italy.

Aflatoxin B1 was extracted from cannabis inflorescence by partitioning in 80% methanol. The adapted enzyme immunoassay was modified (from eggs [5]) for an herbaceous matrix and was in-house validated. They used a polyclonal antibody and an enzyme that competed with aflatoxin B1 to bind to the antibody. The enzyme immunoassay was then used to measure aflatoxin B1 levels. The assay was completed in 30 minutes.

High performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) was used to determine the validity of the method.


Results revealed that the enzyme immunoassay was indeed effective in measuring aflatoxin B1 in cannabis.

The contaminant (AFB1) was detected in half of the 14 samples at levels that were higher than recommended European Union standards. The assay was sensitive to the contaminant and had a recovery rate of 78-136%. The method detected as little as 0.35 ng/mL with a range of quantification at 0.4–2 ng/mL. These results are similar to those obtained when HPLC-MS/MS is used to analyze aflatoxin B1 in cannabis inflorescence.

Apart from the method being effective, the researchers noted that this method requires less equipment and training, and it has wider applications, especially in settings with limited resources. [1]

Image Source

Pete Linforth from Pixabay


  1. Nardo FD, et al. Enzyme immunoassay for measuring aflatoxin B1 in legal cannabis. Toxins. 2020;12(4):265. Journal Impact Factor: 3.531, Times Cited: 1 (Semantic Scholar)
  2. Zerihun A, Chandravanshi AS, Debebe A, Mehari B. Levels of selected metals in leaves of Cannabis sativa L. cultivated in Ethiopia. Springerplus. 2015;4:359. Journal Impact Factor: n/a; Times Cited: 16 (Semantic Scholar)
  3. Wilcox J, Pazdanska M, et al. Analysis of aflatoxins and ochratoxin A in cannabis and cannabis products by LC-fluorescence detection using cleanup with either multiantibody immunoaffinity columns or an automated system with in-line reusable immunoaffinity cartridges. Journal of AOAC International. 2020;103(2):494–503. Journal Impact Factor: 1.510, Times Cited: 3 (Semantic Scholar)
  4. Marchese S, et al. Aflatoxin B1 and M1: biological properties and their involvement in cancer development. Toxins. 2018;10(6):214. Journal Impact Factor: 3.531, Times Cited: 74 (Semantic Scholar)
  5. Anfossi L, Di Nardo F, Giovannoli C, Passini C, Baggiani C. Enzyme immunoassay for monitoring aflatoxins in eggs. Food Control. 2015;57:115-121. doi: Journal Impact Factor: 4.258, Times Cited: 14 (Semantic Scholar)

About the author

Lydia Kariuki

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