Carbonyls are reactive compounds that can form adducts with nucleophiles such as GSH. The carbonyl-GSH adducts were examined to evaluate the health implications of vaping-associated carbonyls. First, formaldehyde and trans-2-hexenal sample solutions were prepared with 5 μL of their standards in 1 mL methanol. Then, each reaction mixture contained 50 μL of the carbonyl sample solution, 100 μL of GSH (28.4 mM in MiliQ water), and 1200 μL MiliQ water. The GSH blank sample contained only 100 μL of GSH and 1250 μL MiliQ water. Each reaction mixture was incubated at 37 °C for 120 min, then stored in a −20 °C freezer until LC/EIS-QTOFMS analysis.
The instrument used to analyze the carbonyl-GSH samples was an Agilent Technologies 6545 LC/Q-TOFMS system equipped with an ESI source. The sample mixtures were separated by a Poroshell 120 EC-C18 column (3 × 100 mm, 2.7 µm). The mobile phase A was 0.1% formic acid in water, and mobile phase B was 0.1% formic acid in acetonitrile. The mobile phase gradient was 0% B–100% B from 2 min to 18 min. The column was washed with 100% B and equilibrated with 100% A before running the next gradient. The sample injection volume was 30 µL, and the instrument was operated in the positive ion mode.
The instrument used to analyze the carbonyl-GSH samples was an Agilent Technologies 6545 LC/Q-TOFMS system equipped with an ESI source. The sample mixtures were separated by a Poroshell 120 EC-C18 column (3 × 100 mm, 2.7 µm). The mobile phase A was 0.1% formic acid in water, and mobile phase B was 0.1% formic acid in acetonitrile. The mobile phase gradient was 0% B–100% B from 2 min to 18 min. The column was washed with 100% B and equilibrated with 100% A before running the next gradient. The sample injection volume was 30 µL, and the instrument was operated in the positive ion mode.