Validation of the Soleris® Coliform Method for Detection of Coliform Bacteria in Dried Cannabis Flower: AOAC Performance Tested MethodSM 010302.

Background: The Soleris® Coliform Vial is a growth-based, automated method for detection of coliform bacteria in foods and other consumer products such as nutraceuticals and cosmetics. The method was granted AOAC Performance Tested MethodSM certification for select foods after successful completion of a validation study.

Objective: The objective of the current study was to validate the Soleris coliform method for use with dried cannabis flower (>0.3% delta 9-tetrahydrocannabinol).

Methods: A comparative matrix study was performed in which naturally contaminated dried cannabis flower was tested with the Soleris coliform method and with the U.S. Food and Drug Administration Bacteriological Analytical Manual solid medium method. Multiple lots of dried cannabis flower were obtained, pre-screened for coliforms, and blended to produce test materials at four different contamination levels ranging from 4.5 to 1600 CFU/g. Each material was tested at three different Soleris detection threshold levels determined by the dilution used to inoculate the Soleris vials. Probability of detection analysis was performed to determine if differences in the number of positive results obtained with the two methods were significant.

Results: For all four dried cannabis flower materials, at all three Soleris test thresholds, there were no significant differences in the number of positive results obtained with the Soleris and cultural plating methods as determined by probability of detection analysis at P < 0.05.

Conclusion: The Soleris coliform test is an accurate method for detection of coliform bacteria in dried cannabis flower.

Highlights: The Soleris coliform method provides cannabis industry QC personnel with an effective method for analysis of dried cannabis flower and produces results in 18-24 h.