Metals are among the most ubiquitous environmental contaminants and can enter the tobacco plant through various sources including soil adsorption and fertilizer application. Additional sources of trace levels of metals present in tobacco can be due to the manufacturing process.
The US Food and Drug Administration (FDA) issued guidance on reporting harmful and potentially harmful constituents (HPHCs) in tobacco products and listed several metals (including arsenic [As], cadmium [Cd], chromium [Cr], nickel [Ni], and lead [Pb]) as compounds for reporting. However, no guidance is provided on recommended analytical techniques or testing methodologies.
The objective of this study was to validate a method for the quantitation of selected metals under the Health Canada Intensive (HCI) smoking regime for an electrically heated tobacco product (eHTP). A commercially available linear smoking machine equipped with an electrostatic precipitator unit was used to trap the metals followed by a sample extraction and mineralization before analysis by inductively coupled plasma mass spectrometry (ICP-MS).
The CORESTA Technical Guide N°28 was used to set method detection limits, and lower quantification limits (LOQs) of 0.4 ng/item for Cd and 5.3 ng/item for Ni were reported. The recovery of the method calculated from spiked aerosol extracts was 92-108 %, and the coefficients of variation of repeatability (CVr) ranged from 2-11 % for the majority of elements.
A number of specific sample handling techniques were applied throughout the aerosol collection and analytical process to minimize any potential source of metal contamination from the laboratory environment. The method was validated according to ICH Q2 (R1) Validation of Analytical Procedures and was demonstrated to be selective, precise, accurate, and linear over the intended working range.