Analysis of 21 carbonyl compounds in e-liquids and e-aerosols by gas chromatography-mass spectrometry after PFBHA derivatization
The quantification of carbonyl compounds in e-liquids and e-aerosols is an important tool for the evaluation of new products, in order to explore ways to reduce emissions and estimate potential exposure. In response to this need, a simple and selective gas chromatography- mass spectrometry (GC-MS) method has been validated, allowing for the simultaneous analysis of 21 carbonyl compounds in e-aerosols and e-liquids utilizing an o-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride (PFBHA) derivatization. The carbonyl compounds studied include formaldehyde, acetaldehyde, acetone, propionaldehyde, acrolein, isobutyraldehyde, n-butyraldehyde, methyl ethyl ketone (MEK), methyl vinyl ketone (MVK), crotonaldehyde, glycoaldehyde, acetol, glyoxal, methylglyoxal, hexanal, benzaldehyde, acetoin, 2,3-butanedione (diacetyl), 2,3-pentanedione (acetyl propionyl), 2,3-hexanedione, and 2,3-heptanedione.
For e-liquids, a 0.5 g sample was diluted with water and derivatized with PFBHA. For e-cigarette aerosols, carbonyls were collected by passing the aerosol through a 44mm glass fiber filter pad into a cryogenic trap (≤ 35°C) containing 20mL of acetonitrile. The pad was extracted with the trapping solution. 1mL of the extract was diluted with water and derivatized with PFBHA. The PFBHA derivatives were then extracted into toluene and analyzed by GC-MS in selected ion monitoring (SIM) mode. This method featured higher sensitivity and specificity. Most of investigated carbonyl compounds can be analyzed at levels below 0.1 µg/g for e-liquids and 1.0 µg/collection for e-aerosols.
The method showed good linearity over two orders of magnitude of concentration. The accuracy and precision of the method were evaluated using fortified e-liquids and e-aerosols. Multiple deuterated carbonyl compounds were added as internal standards to improve accuracy and precision. The mean recoveries from various fortified e-liquids and e-aerosols ranged from 84 and 119% and the precision (CV) below 18% for all analytes. This validated method provides an accurate and robust means to quantify 21 carbonyl compounds in a broad range of e-liquids and e-aerosols.