A liquid chromatography tandem mass spectrometric method for in vivo dose monitoring of diepoxybutane, a metabolite of butadiene

1,3-Butadiene, a common air pollutant formed in the combustion of organic m atter, has been assessed by the U.S. EPA to be a strongly carcinogenic comp ound. This risk assessment is very uncertain because of the lack of informa tion on the dose of the powerful carcinogenic metabolite diepoxybutane (DEB ), This report presents an analytical method for in vivo dose monitoring of a unique marker for DEB, For a large number of alkylating agents in vivo d oses are monitored by measurement by gas chromatography/mass spectrometry ( GC/MS) of adducts to N-terminal valine in hemoglobin (Hb), using a modified Edman degradation method. This method is applicable to monofunctional epox ides from butadiene, However, in reaction with N-terminal valine, DEB forms an adduct which is ring-closed to a pyrrolidine, N,N-(2,3-dihydroxy-1,4-bu tadiyl)valine, with a tertiary amino group that prevents detachment of the alkylated valine by the Edman reagent. Therefore a method has been develope d based on the analysis by liquid chromatography/electrospray ionization ma ss spectrometry (LC/ESI-MS) of the N-modified N-terminal peptides enriched after trypsin digestion of globin, In this study Hb samples from mice injec ted intraperitoneally with (+/-)-DEB were examined qualitatively and quanti tatively with regard to the ring-closed adduct, The N-terminal pyrrolidine- heptapeptide was identified in treated mice. The highest adduct levels were obtained in samples from animals given the highest dose of DEB and the add uct levels were below the detection level in control mice. Copyright (C) 20 00 John Wiley & Sons, Ltd.