Our study have developed methods and assessed the levels of eight groups of compounds in 55 refill solutions for 17 brands in the Chinese market. Our study shows that propylene glycol and glycerol constitute the major ingredients of most refill solutions, and also indicated the necessity for clearly and accurately labeling nicotine content of e-liquids. Compounds that may originate from tobacco, solvents or other sources, such as TSNAs, solanesol, VOCs, PAHs, phenolic compounds, and carbonyl compounds were all found with different levels and detection frequencies.

Evaluating the source of nicotine in e-liquid is a problem. Tobacco-derived nicotine contains predominantly (S)-(-)-nicotine, whereas tobacco-free nicotine products may not. Thus, we developed a new normal phase high-performance liquid chromatography method to determinate the enantiomeric composition of nicotine in 10 kinds of flue-cured tobacco, 3 kinds of burley, 1 kind of cigar tobacco, 2 kinds of oriental tobacco, 5 kinds of Virginia cigarette, 5 kinds of blend cigarette, 10 kinds of e-liquid, and 4 kinds of smokeless tobacco. The amount of (R)-(+)-nicotine ranged from ~0.02% to ~0.76% of total nicotine. An e-liquid sample had the highest level of (R)-(+)-nicotine. The extraction and purification processes used to obtain commercial (S)-(-)-nicotine from the tobacco do not decrease the amount of (R)-(+)-nicotine in tobacco. So the amount of (R)-(+)-nicotine in samples in our work were the same as tobacco samples.

An effective palladium-catalyzed oxidative C-H/C-H cross-coupling of imidazopyridines with azoles using air as the oxidant has been developed. This protocol provides a straightforward and operationally simple method for the synthesis of 3-azolyl-imidazopyridines in moderate to good yields and with good functional group tolerance. The biological evaluation revealed that the newly synthesized compounds 3e and 3h exhibit significant in vitro antiproliferative activities against human-derived lung cancer cell lines compared with the positive control, 5-fluorouracil.

Nicotine lactate, nicotine tartrate, nicotine benzoate, and freebase nicotine (FBN) are four forms of nicotine salt systems that are present in tobacco products. However, few in vivo studies have compared their pharmacological (pK) efficacies, which are important for understanding their roles in the addiction and abuse of tobacco and nicotine products. In this work, the pK of the above nicotine salt systems was studied by subcutaneously injecting their aqueous solutions in rats and obtaining blood samples from the jugular vein. Nicotine levels in the blood were analyzed by LC–MS/MS. The results demonstrated that rapid nicotine absorption occurred in all nicotine systems. Of them, NB had the smallest Tmax, while FBN had the largest Tmax. The nicotine metabolic rate and clearance decreased for FBN, indicating that nicotine retention in the body was higher than for the other three salt‐based systems. Compared with nicotine salts, FBN could reach and maintain a higher concentration in the animal model. Additionally, as the benzoic acid ratios increased, the Cmax of the nicotine benzoate (NB) in the plasma decreased. This indicates that the lower the pH, the lower the Cmax. When different concentrations of NB were used, the higher the NB concentration, the greater the Cmax and AUC(0‐t). These results demonstrate that nicotine adsorption by NB in the animal model depended on both pH and concentration. This baseline information could be used to explain different clinical pharmacological observations in humans, though this study only considered the effects of nicotine on pharmacokinetics in vivo.