2.5. GC-MS Analysis of B[a]P Compound

B[a]P in unheated and heated WP tobacco, and unburned and burned WP charcoal samples (1 g of solid sample each), was extracted by sonication (at 30 or 50°C for 2 hours) using 15 mL of toluene. Each extract was spiked with deuterated perylene as an internal standard and passed through an SPE cartridge using 10 mL of hexane. Each eluent was concentrated to dryness using a nitrogen evaporator (Organomation N-evap Analytical Evaporator, model 111) at room temperature, and brought back up to 100 μL with acetonitrile (ACN), prior to analysis using GC-MS (Agilent 6890N GC with an Agilent 5975MS), operated in selected ion monitoring mode (SIM), using established methods [10] [48] [49] [50]. The quantitation ion (m/z) and confirmation ion (m/z) were 252 and 253, respectively.