Identification and structural elucidation of ozonation transformation products of estrone

Abstract

BackgroundQuantitative methods for the analysis of contaminants of emerging concern (CECs) are abundant in the scientific literature. However, there are few reports on systematic methods of identification and structural identification of transformation products. For this reason, a new method based on high-resolution mass spectrometry and differential analysis was developed in order to facilitate and accelerate the process of identification and structural elucidation of transformation products CECs. This method was applied to the study of ozonation transformation products (OTPs) of the natural hormone estrone (E1).ResultsA control compare trend experiment consisting in the comparison of a control sample to several samples having been exposed to decreasing concentrations of O3(aq) indicated that 593 peaks could be associated with OTPs. After applying various filters to remove background noise, sample contaminants and signal spikes, this data set was reduced to 16 candidate peaks. By inspection of the shape of these peaks, only two compounds OTP-276 (m/z 275.12930) and OTP-318 (m/z 317.14008) were considered as good candidates for further study. Multi-stage tandem mass spectrometry (MSn) experiments of SPE extracts of the ozonated samples of E1 and of a deuterium-labeled analogue (E1-d4) showed that OTP-276 and OTP-318 had carboxylic acid and hydroxyl functional groups, as previously reported for OTPs of other hormones. Structures for these two compounds were proposed based on their MSn spectra.ConclusionThese results indicate that the method proposed is a systematic and rapid approach to study transformation products of CECs.

A review of what is an emerging contaminant

“…In the last decade, we also observed new emerging issues related to chemical contaminants such as, sensitivity to toxic chemicals related to climate change, natural and anthropogenic chemicals related to hydraulic fracturing and shale gas exploitation, increase of mining activities related to rare earths or radionuclides, treatment by-products produced during water treatment (e.g. [ 20 , 21 ]), etc. What are the next issues of concern and which new or old contaminants will be related to them?…”

“…Treatment can focus on conceptually simpler biological processes such as constructed wetlands which can nevertheless be quite efficient [ 40 ] or more complex chemical treatment such as oxidation with chloration or permanganate [ 57 ]. Ozone is often proposed as an alternative or additional treatment that could potentially reduce or eliminate such by-products but ozone itself is so reactive that it is also a major means of producing a suite of by-products, examples are given for the identification of the transformation products of antidepressor drugs [ 20 ] or for a natural estrogen [ 21 ]. Given that ozone is becoming increasingly popular, we can expect more work to emerge on identifying by-products of incomplete ozone treatment and their quantification.…”

Ozonation of wastewater: Removal and transformation products of drugs of abuse

“…The method used to identify potential oxidation transformation products significantly reduces the time required to sift through all of the data obtained by HRMS and is described in detail in Segura et al (2013). Briefly, the main potential OTPs of each compound of interest are identified using the differential expression analysis software Sieve 2.0 (Thermo Scientific).…”

“…The chemical formulae of each OTP listed in Table 2 were chosen from a short list generated within QualBrowser based on their absolute mass accuracy in milli-mass units (Δmmu) and their ring and double bond equivalents (RDBE) value. The OTP retention times are also listed in the table and with the exception of COC's two OTPs and OTP-332 of OXY, all of the OTPs had lower retention times than the parent compound, which can be expected due to the tendency of OTPs to be more hydrophobic than the parent compound (Segura et al, 2013). The "Transient/Persistent" column indicates whether the OTP was detected at an intensity N 1E5 at the highest ozone dose tested.…”

Various Methods for Removal, Treatment, and Detection of Emerging Water Contaminants

“…The target compounds could be quickly and efficiently converted into small inorganic molecules, such as CO 2 and H 2 O. Among the advanced oxidation methods used to remove or reduce the concentrations of some hormones and PPCPs from wastewater, ozone oxidation is the most promising technique [86][87][88][89][90][91][92]. In secondary effluents, ozonation was found to be very useful in decreasing the concentrations of bisphenol-A, estriol, and 17-β estradiol and their estrogenicity [92,93].…”