title: Methyl vinyl ketone--identification and quantification of adducts to N-terminal valine in human hemoglobin.
abstract: Adducts to N-terminal valines in Hb have been shown useful as biomarkers of exposure to electrophilic compounds. Adducts from many compounds have earlier been measured with a modified Edman degradation method using a GC-MS/MS method. A recently developed method, the adduct FIRE procedure™, adopted for analysis by LC-MS/MS, has been applied in this study. With this method a fluorescein isothiocyanate (FITC) reagent is used to measure adducts (R) from electrophiles with a modified Edman procedure. By using LC-MS/MS in product ion scan mode, a new peak was identified and the obtained MS data indicated that this adduct could originate from methyl vinyl ketone (MVK). Incubation of human-, sheep- and bovine blood with MVK increased the signal of the identified peak. By comparing the LC-MS/MS data from the unknown background peak with data obtained from synthesized fluorescein thiohydantoin (FTH) standards of the MVK adduct to valine and d(8)-valine, the identity of this adduct was confirmed. The MVK adduct was shown present in human blood (∼35 pmol/g globin, n=3) and only just above LOD in bovine blood, n=1 (LOD=2 pmol/g globin). MVK reacts, in similarity with acrylamide, via Michael addition. MVK is known to occur in the environment and has earlier been observed in biological samples, which means that there are possible natural and anthropogenic exposure sources. Analysis of an Hb adduct from MVK in humans has to our knowledge not been described before.
authors.affiliation: Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, Svante Arrhenius väg 16C, SE-106 91 Stockholm, Sweden. hans.stedingk@mmk.su.se
authors.forename: Hans
authors.initials: H
authors.lastname: von Stedingk
authors.forename: Ronnie
authors.initials: R
authors.lastname: Davies
authors.forename: Per
authors.initials: P
authors.lastname: Rydberg
authors.forename: Margareta
authors.initials: M
authors.lastname: Törnqvist
mesh_terms: D002074:Butanones / Q000032:analysis*; D002138:Calibration; D002849:Chromatography, Gas / Q000379:methods; D002853:Chromatography, Liquid / Q000379:methods; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D006454:Hemoglobins / Q000737:chemistry*; D006801:Humans; D053719:Tandem Mass Spectrometry / Q000379:methods; D014633:Valine / Q000737:chemistry*
chemical_list: D002074:Butanones; D005456:Fluorescent Dyes; D006454:Hemoglobins; C057920:3-buten-2-one; D014633:Valine; D016650:Fluorescein-5-isothiocyanate