New Analytical Method for Quantifying Flavoring Chemicals of Potential Respiratory Health Risk Concerns in e-Cigarette Liquids

Abstract

Numerous flavoring chemicals are added to e-cigarette liquids to create various flavors. Flavorings provide sensory experience to users and increase product appeal; however, concerns have been raised about their potential inhalation toxicity. Estimating potential health risk of inhaling these chemicals has been challenging since little is known about their actual concentrations in e-cigarette products. To date, a limited number of analytical methods exist to measure the concentrations of flavoring chemicals in e-cigarette products. We have developed an analytical method that accurately and precisely measures the concentrations of 20 flavoring chemicals of potential inhalation risk concerns: 2,3,5-trimethylpyrazine, acetoin, benzaldehyde, benzyl alcohol, butanoic acid, dl-limonene, ethyl maltol, ethyl salicylate, ethyl vanillin, eucalyptol, eugenol, furaneol, isovanillin, l-menthol, maltol, methyl salicylate, pulegone, trans-cinnamaldehyde, triacetin, and vanillin. Calibration and QC solutions were prepared in 50:50 propylene glycol (PG):vegetable glycerin (VG) and 5% H2O and flavoring concentrations ranging from 0.02 to 10.00 mg/ml. Samples of commercial e-cigarette liquids, calibration and QC solutions were combined with 30 µL of an internal standard mix (benzene-d6, pyridine-d5, chlorobenzene-d5, naphthalene-d8 and acenaphthene-d10; 1 mg/ml each) and were diluted 100-fold into methanol. Analysis was performed on an Agilent 7890B/7250 GC/Q-TOF using a DB-624UI column (30 m x 0.25 mmID x 1.4 μm film thickness), with a total runtime of 13.5 min. Calibration curves were fit using a weighted quadratic model and correlations of determination (r2) values exceeded 0.990 for all chemicals. Bias and precision tests yielded values less than 20% and lower limits of quantitation (LLOQ) ranged from 0.02 to 0.63 mg/ml. Over 200 commercially available products, purchased or collected from adult e-cigarette users and spanning a range of flavor categories, were evaluated with this method. Concentrations of pulegone, a suspected carcinogen, varied from below limit of quantitation (BLOQ) to 0.32 mg/ml, while acetoin and vanillin, known precursors to more cytotoxic byproducts, ranged from BLOQ to 1.52 mg/ml and from BLOQ to 16.22 mg/ml, respectively. This method features a wide dynamic working range and allows for a rapid routine analysis of flavoring additives in commercial e-cigarette liquids.

Removal of mango-flavoured Juul pods created opportunity for adulterated mango Juul-compatible pods with altered chemical constituents

“…Ingredients in e-liquids were identified using GC-MS as described previously. 15 Quantitation of select flavours was conducted with GC quadrupole time-of-flight (GC/Q-TOF) using Agilent 7890B (GC) and 7250A (Q-TOF) and a fully validated method as described previously. 16 Flavour calibration range was between 0.02 and 10.0 mg/mL.…”

Changes in product labelling practices and the use of flavouring chemical additives in vaping products after enactment of statewide flavour legislation

“…Concentrations of benzaldehyde (fruity, cherry), benzyl alcohol (fruity), ethyl maltol (sweet), ethyl vanillin (sweet, vanilla), furaneol (caramellic), maltol (sweet), menthol (cooling, minty) and vanillin (sweet, vanilla) were measured using a 7890B/7250 GC/Q-TOF equipped with a PAL RSI 120 autosampler (CTC Analytics, Zwingen, Switzerland) and DB-624 UI (30 m, 250 µm ID, 1.4 µm film thickness) analytical column (Agilent Technologies, Santa Clara, California, USA) using a fully validated method. Calibration procedures and method parameters have been previously described elsewhere 32…”

Two Fast GC-MS Methods for the Measurement of Nicotine, Propylene Glycol, Vegetable Glycol, Ethylmaltol, Diacetyl, and Acetylpropionyl in Refill Liquids for E-Cigarettes

“…For the determination of nicotine and flavoring chemical concentrations in e-liquid refill samples, a limited number of analytical methodologies exists based on gas chromatography–mass spectrometry (GC-MS) [ 5 , 6 , 7 , 8 , 9 , 10 ], liquid chromatography–mass spectrometry (LC-MS) [ 11 ], and nuclear magnetic resonance (NMR) [ 12 , 13 ].…”