An improved in situ acetylation with dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry for the sensitive determination of phenols in mainstream tobacco smoke.

Phenols in tobacco smoke can adversely affect health with serious consequences that include cardiovascular toxicity, tumor promotion and genotoxic activity. Hence, an improved method involving in situ acetylation and dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography-mass spectrometry (GC-MS) was developed for the determination of 39 phenols in mainstream tobacco smoke (MTS). The in situ acetylation was optimized using four protocols, after which the effects of experimental variables on acetylation efficiency were studied using a multifactorial experimental design. The optimum conditions were found to involve an initial 75 µL volume of acetic anhydride, 140 mg of NaHCO3 and 72 mg of K2CO3. The phenolic acetates were then subjected to DLLME, after which they were identified and quantified by GC-MS. A total of 32 additional phenols were tentatively identified. Good linearity was observed with R > 0.999 and each lack-of-fit P > 0.05. The relative recoveries were in the range of 94.8-104.3% with repeatabilities and reproducibilities less than 5.5% and 6.8%, respectively. The limits of detection ranged from 1.12 to 1.74 ng cig-1, with high enrichment factors between 87 and 144. This method was applied to the MTS from three commercial cigarettes with different tar levels. The results provide valuable information for assessing the risks of phenols.