Structural Characterization of Photodegradation Products of Enalapril and Its Metabolite Enalaprilat Obtained under Simulated Environmental Conditions by Hybrid Quadrupole-Linear Ion Trap-MS and Quadr
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- 作者：Sandra Pé ; rez ; Peter Eichhorn ; Damià ; Barceló
- 刊名：Analytical Chemistry
- 出版年：2007
- 出版时间：November 1, 2007
- 年：2007
- 卷：79
- 期：21
- 页码：8293 - 8300
- 全文大小：161K
- 年卷期：v.79,no.21(November 1, 2007)
- ISSN：1520-6882
文摘
In the environment, organic micropollutants such aspharmaceuticals can be degraded via various biotic andabiotic transformation routes. In surface waters, forexample, photodegradation may constitute a relevantnatural attenuation process for drug residues that havebeen discharged from sewage treatment facilities. In thepresent work, the photochemical fate of the prodrugenalapril (376 Da, C20H28N2O5) and its active metaboliteenalaprilat (348 Da, C18H24N2O5), a hypotensive cardioprotector previously reported to occur in contaminatedrivers, was investigated in aqueous media under theinfluence of irradiation generated by a sunlight simulator.The experiments yielded three detectable photodegradatesfor enalapril (346 Da, 2 × 207 Da) whereas the photolysisof enalaprilat went hand in hand with the intermittentbuildup of one photodegradate (304 Da). Fragmentationpatterns of the parent compounds were established on ahybrid quadrupole-linear ion trap-mass spectrometerexploiting its MS3 capabilities. Accurate mass measurements recorded on a hybrid quadrupole-time-of-flightinstrument in MS/MS mode allowed us to proposeelemental compositions for the molecular ions of thedegradates (346 Da, C19H26N2O4; 207 Da, C12H17NO2;304 Da, C17H24N2O3) as well as of their fragment ions.Based on these complementary data sets from the twodistinct mass spectrometric instruments, plausible structures were postulated for the four photodegradates. Thecompounds formed by enalapril corresponded to the lossof formaldehyde out of the proline residue (346 Da),cleavage of the central amide bond (207 Da) followed bymigration of the ethylester side chain (207 Da) whiledecarboxylation of the free carboxylic acid was describedfor enalaprilat (304 Da). The study emphasized thepotential of sunlight for breaking down an environmentallyrelevant drug and its metabolite.