| Abstract: | Third‐hand smoke (THS) can be defined as the contamination of surfaces by second‐hand smoke. This residue can form further pollutants which can be re‐suspended in dust or be re‐emitted into the gas phase. THS is a complex mixture and as a result studies have focused on nicotine as a marker of THS, it being the most abundant and indicative organic compound deposited. In this present study, the extraction of dust wipe samples and the subsequent chromatographic conditions required for the separation of nicotine by liquid chromatography with electrochemical detection were investigated and optimised. The optimum chromatographic conditions were identified as a 150 mm×4.6 mm, 5 µm C18 column with a mobile phase consisting of 65 % methanol, 35 % pH 8 20 mM phosphate buffer. Hydrodynamic voltammetry was used to optimise the applied potential which was identified to be +1.8 V (vs . stainless steel). Under these conditions, a linear range for nicotine of 13 to 3240 µg/L (0.26 ng–65 ng on column) was obtained, with a detection limit of 3.0 µg/L (0.06 ng on column) based on a signal‐to‐noise ratio of three. Dust wipe samples were extracted in methanol with the aid of sonication. Mean recoveries of 98.4 % (% CV=7.8 %) were found for dust wipe samples spiked with 6.50 µg of nicotine. Musk ketone, urea and stearic acid were found not to interfere. Communal entrance ways were found to be contaminated with THS nicotine levels of between 66.8 and 156 µg/m2. |
