Metals in Hemp and Cannabis

Question

Greetings All, 
 I just finished watching the webinar regarding the AOAC method for cannabis and hemp. From what I gather, it is recommended to use 0.5g of material, 10 mLs of concentrated acid (9mLs nitric and 1 mL hydrochloric) then the final digest is taken up to a volume of 50mLs with DI water. That makes for a sample having 1% TDS and a 20% acid concentration. Is there another dilution of the sample somewhere in the method before introduction to the instrument? I don't see anything in any of the documentation or the presentation materials. I'm trying to wrap my head around the final sample matrix and the concentrations that the instrument is actually measuring. 
 Thanks, 
 Tom

evanclay · Answer

Hello Tom, 
 There was no other dilution applied to the prepared cannabis samples prior to analysis. The calibration standards were prepared using a mix of 1% nitric and 0.5% hydrochloric acid. 
 The acid concentrations in the final sample digests are higher than those used for the calibration standards. However, it was noted that these acid concentrations gave reliable digestion of all the sample matrices and good chemical stability for all the analytes. 
 There is more detail available in the Agilent application note titled "Determination of Heavy Metals in Cannabis and Hemp Products Following AOAC Method for ICP-MS - Routine monitoring of As, Cd, Hg, Pb, and other elements using an Agilent 7850 ICP-MS" available for review/download from the Agilent website at this URL: https://www.agilent.com/cs/library/applications/application-cannabis-aoac-7850-icp-ms-5994-4080en-agilent.pdf 
 Hope that addresses your question, Cheers Eric

Metals in Hemp and Cannabis

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