Elucidation of the decomposition pathways of protonated and deprotonated estrone ions: application to the identification of photolysis products

Abstract

With the future aim of elucidating the unknown structures of estrogen degradation products, we characterized the dissociation pathways of protonated estrone (E1) under collisional activation in liquid chromatography/tandem mass spectrometry (LC/MS/MS) experiments employing a quadrupole time-of-flight mass spectrometer. Positive ion and negative ion modes give information on the protonated and deprotonated molecules and their product ions. The mass spectra of estrone methyl ether (CH(3)-E1) and estrone-d(4) (E1-d(4)) were compared with that of E1 in order (i) to elucidate the dissociation mechanisms of protonated and deprotonated molecules and (ii) to propose likely structures for each product ions. The positive ion acquisition mode yielded more fragmentation. The mass spectra of E1 were compared with those of estradiol (E2), estriol (E3) and 17-ethynylestradiol (EE2). This comparison allowed the identification of marker ions for each ring of the estrogenic structure. Accurate mass measurements have been carried out for all the identified ions. The resulting ions revealed to be useful for the characterization of structural modifications induced by photolysis on each ring of the estrone molecule. These results are very promising for the determination of new metabolites in the environment.

MALDI Mass Spectrometric Analysis of Nonderivatized Steroids Using Cyclodextrin-supported 2,5-Dihydroxybenzoic Acid as Matrix

“…Chemical structures presented in Figure 4(c) are possible product ions of protonated estrone ions. 1,[10][11][12] This suggests that αCD-supported DHB MALDI MS has a potential advantage over other SALDI MS methods in structural analysis of neutral steroids and also in complex steroid mixture analysis.…”

Identification and ecotoxicity of degradation products of chloroacetamide herbicides from UV-treatment of water

“…Reverse phase chromatographic separations were performed using a "Pursuit XRs Ultra" column 2.8 µm C18 50 x 2.0 mm from Varian. Chromatographic and spectrometric conditions were adopted as in our previous work (Bourcier et al, 2010).…”

“…The relative abundance and suggested structures of the photo degradation products are presented in Table 2. The methodology for characterization of degradation products is fully described in previous published studies (Bourcier et al, 2010;Bouchonnet et al, 2011;Bouchonnet et al, 2012;Souissi et al, 2012;) in which we described how establishment of characteristic dissociation pathways of molecular ions permitted systematic structure elucidation of degradation products. The detailed structure elucidation of the photoproducts of metolachlor is described in and the similar identification of the same products of alachlor and acetochlor is supported in the the data and the mechanistic interpretations of the mass spectras are supported by the data shown in supporting information namely figures S6, S7 and S8 as well as tables S2 and S3.…”

“…This analytical strategy has been developed and applied to allow reliable identification of numerous degradation products. Our strategy combined three complementary major steps for generating data that could be used to identify the degradation products: collision induced dissociation for fragmentation mechanism establishment, high resolution measurements for elemental composition determination and use of isotope labelled molecules for structural confirmation (Bourcier et al, 2010;Bouchonnet et al, 2011;Bouchonnet et al, 2012;Souissi et al, 2012;. The labelled molecules allow the location of structural modifications induced by UV irradiation through the comparison of data with those of unlabelled molecules ).…”

Mechanism of Formation of the Major Estradiol Product Ions Following Collisional Activation of the Molecular Anion in a Tandem Quadrupole Mass Spectrometer

“…Little has been published regarding the structure of the product ions used in those quantitative assays in particular the two abundant product ions used in most MRM based methods, m/z 145 and m/z 183. While the former product ion, m/z 145, has been previously characterized and is well understood [5,6,8,13], the proposed structure of the very abundant product ion m/z 183 has not been rigorously established [5,7]. …”