Sensitive Determination of Ethyl Carbamate in Smokeless Tobacco Products and Cigarette Smoke Using SPE and HPLC-APCI-MS/MS

Ethyl carbamate occurs not only in a wide range of alcoholic beverages and fermented foods such as bread, yoghurt, or soy sauce but also in fruit and vegetable juices. Apart from that, traces of ethyl carbamate have been found in tobacco smoke and smokeless tobacco products such as moist snuff or snus. A highly efficient purification technique was established for ethyl carbamate from smokeless tobacco products and tobacco mainstream smoke. After extraction using an aqueous buffer, a polymeric-reversed phase material is used to purify the extracts. Aqueous buffer with 10 % methanol is sufficient to elute the highly polar analyte from the column while matrix components remain on the column. Final determination of ethyl carbamate is performed using HPLC-APCI-MS/MS. Ethyl carbamate-d(5) is used as internal standard to correct the peak areas before quantification via external standard calibration. A comparison of ionization techniques, APCI and ESI, showed that APCI gives a significantly improved sensitivity. Reference cigarettes (tobacco mainstream smoke) as well as reference smokeless tobacco products (CRP1-4) were analyzed, but only CRP2 showed detectable levels of 38 A mu g kg(-1). Recoveries ranged from 80 % in CRP2 to 45 % in CRP3. Furthermore, extensive validation data are presented.