Analytical Method for Measurement of Tobacco-Specific Nitrosamines in E-Cigarette Liquid and Aerosol

Abstract

An experimental method was developed and validated for the collection and analysis of tobacco-specific nitrosamines (TSNAs) that are present in electronic cigarette (EC) liquid or are released from aerosol samples using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) system. As part of this study, the relative recovery of four target TSNAs was assessed by spiking standards in a mixture of propylene glycol and vegetable glycerin. Recovery was assessed against two major variables: (1) the chemical media (solution) selected for sample dilution (acetonitrile [ACN] vs. ammonium acetate [AA]) and (2) the type of sampling filter used (Cambridge filter pad [CFP] vs. quartz wool [QW] tube). The average recovery of TSNAs in terms of variable 1 was 134 ± 22.1% for ACN and 92.6 ± 8.27% for AA. The average recovery in terms of variable 2 was 83.4 ± 7.33% for QW and 58.5 ± 12.9% for CFP. Based on these conditions, the detection limits of N′-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N′-nitrosoanatabine (NAT), and N′-nitrosoanabasine (NAB) were calculated as 4.40, 4.47, 3.71, and 3.28 ng mL−1, respectively. The concentration of TSNAs in liquid and aerosol samples of six commercial EC solutions was measured as below the detection limit.

Selected Harmful and Potentially Harmful Constituents Levels in Commercial e-Cigarettes

“…The results are in line with what has been previously observed in commercial e-cigarette products, ,,− where TSNAs were found in trace amounts only in some of the analyzed products.…”

“…Very few results were above the LOQ in the liquids or in their aerosols. This corresponds to observations by other authors for commercial products ,,,,, and is also reflected in the reduction of TSNA biomarkers for cigarette smokers who switch to e-cigarettes. − , …”

Ultrasound-Assisted Solvent Extraction of a Porous Membrane Packed Sample for the Determination of Tobacco-Specific Nitrosamines in the Replacement Liquids for E-Cigarettes

“…Example chromatograms obtained after the dilution (100 × with mobile phase) of sample 6 and 9 are presented on the Figure S2. Moreover, the multistep extraction presented in a paper by Kim et al [9] is omitted, the samples are not diluted, and the matrix influence is significantly reduced [4,13]. The ability of the main components (PG and VG) to interfere with the determination of TSNAs is strongly reduced, so high recovery values were obtained.…”

“…As mentioned before, TSNAs can be extracted together with nicotine from tobacco leaves. Liquid and aerosol TSNAs occur at trace levels (up to several dozen ng/mL of e-liquids or puffs) or at the limits of the detection or quantitation of the analytical procedure used [4,13]. However, some research indicates increased levels of these compounds in e-liquid samples, when sample preparation is based on solid phase extraction (SPE) or liquid-liquid extraction (LLE) [9].…”

“…However, gas chromatography coupled with a thermal energy analyzer (GC-TEA) was successfully applied to determine these analytes in tobacco and tobacco smoke [22][23][24][25], including analysis of other tobacco-related products [26]. Several papers are focused on determining TSNAs in e-liquids and aerosols using LC-MS/MS [9,13,27,28]. The analytes in e-liquids and in corresponding aerosols are at trace levels; hence, dilution of the sample and the presence of a matrix may strongly influence the detection and reliability of the obtained results.…”