AOAC CASP Meeting - MYM 2020

Nature of Comment

Comment

Change/Recomm endation

Definitions, cont’d • Recovery: You have to be more specific when defining spike recoveries. Your definition is totally inadequate,. Check out USP Chapter 233 for guidance. Method Performance Requirements: What if the repeatability is outside these specs. The achievable precision for any element is going to be impacted by the instrument sensitivity for that element. Pb is very a very sensitive element, while As is mono ‐ isotopic and is not well ionized in the plasma. In addition, if HCl is used in the sample prep, it will produce an ArCl polyatomic interference at mass 75 which will totally overlap the As 75. For that reason, I would not include a repeatability/reproducibility spec....I would just have a % recovery spec.. But again what do you do if the results fall outside these windows? Check out ACS Reagent Chemicals methodology for heavy metals for guidance. System Suitability: • Is this section referring to the calibration...it's unclear. If so you need to suggest a calibration range, based on the LOQ and the end of the linear dynamic range for that element. So my suggestion is to use a matrix blank as zero, a 20 ‐ 50x the LOQ as the low standard (made up with the matrix blank) and a high standard which is above your expected highest sample. A mid range standard is then typically used a QC sample. You should check out USP Chapter 233 validation protocols as guidance.

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Nature of Comment

Comment

Change/Recommen dation

Reference Materials: There will not be cannabis reference material for heavy metals for some time. You just cannot use other materials like tobacco, spinach leaves or hops (not sure where infant formula came from), because the elemental suite and range is not well suited for typical levels of Pb, Cd, As and Hg in cannabis flower or cannabis products. This is why a comprehensive, validated spike recovery procedure is the only way you can ensure that high quality and reproducible data. This is the way the FDA regulates pharma labs, because there are no pharmaceutical certified reference materials to assess the validity of the analytical procedure and the accuracy of the generated data.

Validation Guidance and References: I have no idea what this is referring to. Maximum Time ‐ To ‐ Result: I'm not sure I understand what this means. Summary:

As the leader of the heavy metals task on the ACS Analytical Reagents Committee, I have been involved with writing standard methods and procedures for elemental impurities/contaminants regent chemicals for the past 20 years. We worked very closely with the USP when they updated their 100 year old sulfide precipitation heavy metals test for drug materials, at the same we were changing our ACS test. Even though the list of metals were different, the plasma spectrochemistry procedure was very similar. For that reason, I would strongly recommend you take a look at either or both methodologies to help you develop your AOAC heavy metals' method for cannabis and hemp. USP took 20 years to change its method, we took 5 years to update our ACS test. Take advantage of the knowledge and experience that has gone into developing these methods.

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