GC/MS Analysis of E-Liquid Flavors

The extracted e-liquid was analyzed using previously described GC/MS methods^{4 (link)}. Each sample (50 µL) was dissolved in 0.95 mL of isopropyl alcohol and shipped overnight on dry ice to Portland State University. A 20 µL aliquot of internal standard solution (2000 ng/µL of 1,2,3- trichlorobenzene dissolved in isopropyl alcohol) was added to each diluted sample prior to analysis. Using internal-standard-based calibration procedures described elsewhere^{36 (link)} analyses for 178 flavor-related target analytes, two synthetic coolants, and nicotine were performed with an Agilent 5975C GC/ MS system (Santa Clara, CA). A Restek Rxi-624Sil MS column (Bellefonte, PA) was used (30 m long, 0.25 mm id, and 1.4 µm film thickness). A 1.0 µL aliquot of the diluted sample was injected into the GC with a 10:1 split. The injector temperature was 235 °C. The GC temperature program for analyses was 40 °C hold for 2 min, 10 °C/min to 100 °C, then 12 °C/min to 280 °C and hold for 8 min at 280 °C, and then 10 °C/min to 230 °C. The MS was operated in the electron impact ionization mode at 70 eV in the positive-ion mode. The ion source temperature was 220 cc, and the quadrupole temperature was 150 cc. The scan range was 34 to 400 amu. Each of the 181 (178 flavor chemicals, 2 synthetic coolants, and nicotine) target analytes were quantitated using the authentic standard material.