The determination of vitamin E acetate in the liquids of electronic cigarettes is important due to its possible connection to lung injury associated with the use of vaping products. These issues have been predominantly linked to the use of illicit cannabis products where vitamin E acetate has been found in the liquids in the range of 4 % to 40 %. However, it is critical to develop accurate and reliable analytical methods, sensitive enough to demonstrate vitamin E acetate has not been added to any e-cigarette or vaping products.

Two analytical methods for the analysis of vitamin E acetate in e-liquids were developed using a simple dilution of the e-liquid with methanol. The reversed-phase HPLC-DAD (Diode Array Detection) approach offered an applicable range of 10 to 1000 µg/g of e-liquid. The lab fortified blank (LFB) and lab fortified matrix (LFM) recoveries, ranged from 99.3 % to 101 % and 82.1 % to 114 %, respectively. Although this simple and cost-effective method was suitable for quantifying vitamin E acetate in samples when used as a principle component of the liquid, it lacked selectivity and may suffer a positive bias due to interference from matrix components. Therefore, a more sensitive and selective LC-MS/MS method was required.

The LC-MS/MS method provided an applicable range of 100 ng/g to 50 µg/g of e-liquid, using up to 5 MRM transitions. This made it suitable for the analysis of complex liquids, including cannabis liquid matrices. However, characteristics or properties of the compound provided many challenges. The deuterated (-D9) vitamin E acetate internal standard allows for the correction of potential matrix effects with the accuracy and precision from LFM recoveries ranging from 84.5 % to 108 % across a range of fortification levels.

In conclusion, the LC-MS/MS method can accurately quantify trace amounts of vitamin E acetate in both e-liquids and cannabis liquid matrices.