On the extension of the use of a standard operating procedure for nicotine, glycerol and propylene glycol analysis in e-liquids using mass spectrometry.

INTRODUCTION Standard operating procedures (SOP), accessible to several laboratories, are essential for product verification. EU-JATC (European-Joint Action on Tobacco Control) SOP and the WHO TobLabNet (World Health Organization Tobacco Laboratories Network) SOP (SOP11) are available standard methodologies to measure nicotine, glycerol, and propylene glycol, and propose mass spectrometer (MS) as an alternative method to flame ionization detector (FID). This study conducted a comparison between FID and MS concentration results, following the MS method described in SOP11. METHODS In May 2020, five test e-liquids in replicates (A-E) were prepared at the Istituto di Ricerche Farmacologiche Mario Negri and sent, with SOP 11, validation document and results datasheet to 32 different laboratories all over the world from WHO TobLabNet and EU-JATC (18 from JATC, ten from WHO TobLabNet and four academic laboratories). Among thirty-two independent laboratories that participated in the study, results were received from 30 laboratories. RESULTS The e-liquids analyses, using the two approaches, were compared. Of the 30 laboratories surveyed, 21 utilized the FID approach exclusively, 7 opted for MS detection, and 2 employed both methods. The findings demonstrated that the gas chromatography-mass spectrometry (GC-MS) method offers comparable analytical capabilities regarding accuracy and precision for nicotine, glycerol, and propylene glycol to the FID approach. Through Pearson's correlation test with r≃1 showing a positive correlation between GC-FID and GC-MS data, and the Student's t-test, no significant differences between the two approaches were revealed, showing p>0.005 for almost all three analytes in all samples. CONCLUSIONS This study indicates that it is possible to apply the available EU-JATC SOP and the WHO TobLabNet SOP11 even in laboratories that do not have access to an FID, for example, to analyze flavors, trace compounds or carcinogenic, mutagenic, or toxic for reproduction (CMR) in electronic cigarette liquids.