Regarding detection of hydrogen peroxide in cigarette smoke

Abstract

I would like to draw your attention to the paper entitled “Epidermal growth factor receptor exposed to cigarette smoke is aberrantly activated and undergoes perinuclear trafficking,” by Elaine M. Khan, Roni Lanir, Aaron R. Danielson, and Tzipora Goldcorn (1). The authors concluded that hydrogen peroxide present in the cigarette smoke causes epidermal growth factor receptor (EGFR) activation in a ligand-independent way. In this paper the authors estimated the amount of hydrogen peroxide in cigarette smoke using sodium thiocyanate and ferrous ammonium sulfate, and the absorbance of the ferrithiocyanate complex was measured at 480nm. Although this method is suitable for estimation of pure hydrogen peroxide, unfortunately we found that the method is inappropriate to estimate the amount of hydrogen peroxide present in cigarette smoke solution. Cigarette smoke contains strong reducing agents which reduce the ferrithiocyanate complex into ferrothiocyanate, thereby bleaching the red color of ferrithiocyanate complex. When cigarette smoke solution is added to a solution of pure hydrogen peroxide, no significant change in absorbance at 480nm is observed. Thus, it would appear that the method used by the authors is not appropriate for estimating the amount of hydrogen peroxide in cigarette smoke solution. The conclusion drawn by the authors that hydrogen peroxide present in cigarette smoke causes EGFR activation in a ligand independent way is questionable.