Method Validation Analysis of Toxic Elements As, Cd Pb and Hg in Cannabidiol (CBD)-rich Oil by Inductively Coupled Plasma Mass Spectrometry

The development of a method and its validation for determination of toxic elements As, Cd, Pb and Hg in Cannabidiol-rich oil is presented. The samples, 500 mg, were initially treated with 5 mL HNO3 and 4 mL H2O2 followed by digestion in a microwave system. The clean solutions were subsequently diluted with deionized water and the analytes quantitated by inductively coupled plasma mass spectrometry (ICP-MS). Instrumental conditions were carefully evaluated, including the use of correction equations and He collisional gas (KED) to avoid/correct for possible interferences such as 40 Ar 35 Cl affecting 75 As. Limits of quantitation (LOQs, calculated from replicate measurements of method blanks) were: 0.01 mu g g(-1) (As), 0.001 mu g g(-1) (Cd and Pb), and 0.0005 mu g g(-1) (Hg) based on processing 500 mg subsamples/50 mL. The accuracy of the method was confirmed by spiking the Cannabidiol-rich oil sample at different concentration levels and determining recoveries with acceptable results under repeatability and intermediate precision conditions. Eight commercially available formulations were analyzed and only one showed 0.14 mu g g(-1) Pb. The present fit-for-purpose analytical method is robust and precise and was adopted for use by the Tecpar`s laboratory of the Parana Institute of Technology (Curitiba, Brazil).