Tiandong Zhang

Preparation of nicotine surface molecularly imprinted polymers for selective solid-phase extraction of nicotine from zero-level refill liquids of electronic cigarettes

A new method of molecularly imprinted polymer solid-phase extraction (MISPE) coupled with gas chromatography-mass spectrometry was developed for the determination of nicotine in the zero-level refill liquids of electronic cigarettes. The surface molecularly imprinted polymers (SMIP) were synthesized on the surface of vinyl-SiO2 nanospheres using nicotine as a template, methacrylic acid as a functional monomer, and ethylene glycol dimethacrylate as a cross-linker in toluene solution. The prepared SMIPs showed high adsorption capacity (247.0 μmol g−1), excellent imprinting factor (4.40), and high selectivity toward nicotine with selectivity coefficients higher than 2.9. Finally, the SMIPs were successfully utilized as solid-phase extraction (SPE) sorbents for the extraction of nicotine in the zero-level refill liquids of electronic cigarettes (ECs). The newly established method showed good linearity in the range of 2.00–40.00 μg mL−1. The limit of detection (LOD, S/N = 3) was 0.50 μg mL−1, the limit of quantification (LOQ, S/N = 10) was 1.66 μg mL−1, and the average recoveries range from 76.2% to 83.9% with relative standard deviations lower than 6.4% (n = 6). These results indicated that a feasible and reliable method was developed for the determination of nicotine in zero-level refill liquids of electronic cigarettes, which could provide an alternative solution for the quality control of electronic cigarette products.

Effects of tourmaline on growth of three kinds of microorganisms

Tourmaline is a kind of widespread minerals and has been used in many fields of society. Owing to the special electric properties, tourmaline can destroy the hydrogen bond between water molecules. The growth of microorganism may be affected with addition of tourmaline; therefore the effects of tourmaline on three different kinds of microorganisms were studied using microcalorimetric method. The kinetic parameters of growth process were obtained through the thermogenic curves. The results show that high concentration tourmaline inhibited the growth of prokaryotic cells (the growth rate constant of Escherichia coli and Staphylococcus aureus decreased 68.77 and 35.25% at tourmaline concentration of 160 g/L), while promoted eukaryotic cell (the growth rate constant of Candida albicans increased 40.73% at tourmaline concentration of 160 g/L). However, the low concentration tourmaline had complex effects on growth of the studied microorganisms. Key words: Microcalorimetric, water cluster, growth rate, inhibitory ratio.