Simple HPLC method for simultaneous quantification of nicotine and cotinine levels in rat plasma after exposure to two different tobacco products

Purpose: Development and validation of a selective analytical method to accurately and precisely quantify nicotine and cotinine levels in rat's plasma after exposure to tobacco cigarettes and tobacco water-pipe. Methods: An easy HPLC-Photodiode-Array Detection (PDA) method was developed and validated for simultaneous determination of nicotine and cotinine levels in plasma of 15 rats (10 rats after tobacco products exposure and 5 control rats). Nicotine and cotinine were extracted in one step from plasma using acetonitrile and concentrated to lowest volume using nitrogen stream. Results: The developed method offered a rapid analysis time of 14 min with single step of analytes extraction from rat's plasma with recovery percentage range between 93 and 95% and excellent linearity with correlation factor more than 0.994 with analytical range between 50 and 1000 ng mL-1 and LOD of 25 ng mL-1 and 23 ng mL-1 for nicotine and cotinine, respectively. The analysis of rat's plasma after 28 days of exposure to tobacco cigarettes and tobacco water-pipe revealed that the average concentrations of 376 ng mL-1 for cotinine and 223 ng mL-1 for nicotine were obtained after tobacco cigarettes exposure, and 220 ng mL-1 for cotinine and 192 ng mL-1 for nicotine after tobacco water-pipe exposure. Conclusion: Higher nicotine and cotinine levels were found in plasma after tobacco cigarettes exposure than waterpipe exposure which may have potential undesirable effects on passive smokers in both cases.