Recent scientific scrutiny and concerns over exposure, toxicity, and risk have led to international regulatory efforts resulting in the reduction or elimination of certain perfluorinated compounds ...from various products and waste streams. Some manufacturers have started producing shorter chain per- and polyfluorinated compounds to try to reduce the potential for bioaccumulation in humans and wildlife. Some of these new compounds contain central ether oxygens or other minor modifications of traditional perfluorinated structures. At present, there has been very limited information published on these “replacement chemistries” in the peer-reviewed literature. In this study we used a time-of-flight mass spectrometry detector (LC-ESI-TOFMS) to identify fluorinated compounds in natural waters collected from locations with historical perfluorinated compound contamination. Our workflow for discovery of chemicals included sequential sampling of surface water for identification of potential sources, nontargeted TOFMS analysis, molecular feature extraction (MFE) of samples, and evaluation of features unique to the sample with source inputs. Specifically, compounds were tentatively identified by (1) accurate mass determination of parent and/or related adducts and fragments from in-source collision-induced dissociation (CID), (2) in-depth evaluation of in-source adducts formed during analysis, and (3) confirmation with authentic standards when available. We observed groups of compounds in homologous series that differed by multiples of CF2 (m/z 49.9968) or CF2O (m/z 65.9917). Compounds in each series were chromatographically separated and had comparable fragments and adducts produced during analysis. We detected 12 novel perfluoroalkyl ether carboxylic and sulfonic acids in surface water in North Carolina, USA using this approach. A key piece of evidence was the discovery of accurate mass in-source n-mer formation (H+ and Na+) differing by m/z 21.9819, corresponding to the mass difference between the protonated and sodiated dimers.
A suite of analytical tools was applied to thoroughly analyze the chemical composition of an oil/gas well flowback water from the Denver-Julesburg (DJ) basin in Colorado, and the water quality data ...was translated to propose effective treatment solutions tailored to specific reuse goals. Analysis included bulk quality parameters, trace organic and inorganic constituents, and organic matter characterization. The flowback sample contained salts (TDS=22,500 mg/L), metals (e.g., iron at 81.4 mg/L) and high concentration of dissolved organic matter (DOC=590 mgC/L). The organic matter comprised fracturing fluid additives such as surfactants (e.g., linear alkyl ethoxylates) and high levels of acetic acid (an additives' degradation product), indicating the anthropogenic impact on this wastewater. Based on the water quality results and preliminary treatability tests, the removal of suspended solids and iron by aeration/precipitation (and/or filtration) followed by disinfection was identified as appropriate for flowback recycling in future fracturing operations. In addition to these treatments, a biological treatment (to remove dissolved organic matter) followed by reverse osmosis desalination was determined to be necessary to attain water quality standards appropriate for other water reuse options (e.g., crop irrigation). The study provides a framework for evaluating site-specific hydraulic fracturing wastewaters, proposing a suite of analytical methods for characterization, and a process for guiding the choice of a tailored treatment approach.
Opioids, both as prescription drugs and abuse substances, have been a hot topic and a focus of discussion in the media for the last few years. Although the literature published shows the occurrence ...of opioids and some of their metabolites in the aquatic environment, there are scarce data in the application of high resolution mass spectrometry (HRMS) for the analysis of these compounds in the environment. The use of HRMS allows increasing the number of opioids that can be studied as well as the detection of unknown opioids, their metabolites and potential transformation products. In this work, a retrospective analysis for the identification of opioids and their metabolites using a curated database was applied to surface water and wastewater samples taken in the state of Minnesota (U.S.) in 2009, which were previously analyzed by liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS) for antidepressants. The database comprised >200 opioids including natural opiates (e.g. morphine and codeine), their semi-synthetic derivatives (e.g. heroin, hydromorphone, hydrocodone, oxycodone, oxymorphone, meperidine and buprenorphine), fully synthetic opioids (e.g. fentanyl, methadone, tramadol, dextromethorphan and propoxyphene), as well as some of their metabolites (e.g. 6-monoacetylcodeine, dextrorphan, EDDP, normorphine and O-desmethyltramadol). Moreover, additional MS-MS experiments were performed to confirm their identification, as well as to recognize fragmentation patterns and diagnostic ions for several opioids. These data provide a better understanding of the historical occurrence of opioids and their metabolites in surface waters impacted by wastewater sources. The concentrations of individual opioids in surface water and wastewater effluent varied from 8.8 (EDDP) to 1640 (tramadol) ngL−1 and from 12 (dihydrocodeine) to 1288 (tramadol) ngL−1, respectively. The opioids with higher overall frequency detections were tramadol, dextromethorphan and its metabolite, dextrorphan.
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•An accurate mass database for >200 opioids and their metabolites was developed.•Retrospective data analysis was carried out for the identification of opioids and their metabolites.•Historical opioid occurrence in surface water samples from Minnesota was obtained and discussed.•A detailed MS-MS study for several opioids and their metabolites by HRMS is presented.•The most frequently detected opioids in samples were dextromethorphan, dextrorphan and tramadol.
This paper reports the first detections of an antidepressant, lamotrigine, and its major metabolite (2-N-glucuronide), in environmental water samples using a new chlorine mass-filter technique with ...accurate mass and high resolution. A quantitative method is described using solid phase extraction (SPE) followed by liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/Q-TOF-MS) for the simultaneous analysis of both compounds in aqueous samples, including drinking water, groundwater, surface water, and wastewater collected from sewage treatment plants. The recoveries of the analytes ranged from 75 to 99%, depending on the type of water extracted. The method detection limits were 1 and 5 ng/L for lamotrigine and its metabolite, respectively. The method was validated with more than a hundred aqueous samples analyzed and lamotrigine and its 2-N-glucuronide metabolite were mostly detected in both wastewater and surface water impacted sites at mean concentrations of 488 and 209 ng/L, respectively. Lamotrigine was detected in 94% of all the wastewater samples analyzed. Two detections for lamotrigine occurred in drinking water. To our knowledge, this is the first report of water samples containing lamotrigine, a relatively new drug used for the treatment of epilepsy and type I bipolar syndrome. It is also the first report of a glucuronide of an antidepressant surviving wastewater treatment plant operations and becoming a ground and surface water contaminant.
•A novel cannabinoid (epicannabidiol hydrate) was identified in hemp products.•Isolation and purification was successfully achieved by flash chromatography.•Analysis by LC/Q-TOF-MS and NMR verified ...the chemical structure.•α-terpineol is involved in the generation of this new cannabinoid.
A novel and major cannabinoid (epicannabidiol hydrate) present in hemp plants and oils was isolated and characterized by a combination of flash chromatography and liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC/Q-TOF-MS). This novel cannabinoid differs from cannabidiol (CBD) by the absence of a double bond in the terpene ring and the presence of an additional hydroxyl group in the same terpene ring. The isolation procedure involved the use of normal phase chromatography with a silica gel preparative column, followed by reversed phase chromatography with a C18 preparative column. In this way, other major cannabinoids present in the samples, such as cannabidiol and Δ9-tetrahydrocannabinol, were separated and the focus was placed on the novel cannabinoid compound. Exact accurate masses were obtained for the compound of interest at m/z = 333.2424 in positive ion mode and m/z = 331.2279 in negative ion mode. Additional MS-MS analysis in negative ion mode revealed the position of the additional hydroxyl group in the molecule. Finally, the structural characterization was corroborated with 1H NMR and 13C NMR analysis, thus verifying the exact chemical structure of this novel cannabinoid, which has not previously been reported in hemp samples.
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The U.S. Environmental Protection Agency (EPA) Method 1694 for the determination of pharmaceuticals in water recently brought a new challenge for treatment utilities, where pharmaceuticals have been ...reported in the drinking water of 41-million Americans. This proposed methodology, designed to address this important issue, consists of solid-phase extraction (SPE) followed by liquid chromatography–mass spectrometry (LC/MS–MS) using triple quadrupole. Under the guidelines of Method 1694, a multi-residue method was developed, validated, and applied to wastewater, surface water and drinking water samples for the analysis of 70 pharmaceuticals. Four distinct chromatographic gradients and LC conditions were used according to the polarity and extraction of the different pharmaceuticals. Positive and negative ion electrospray were used with two MRM transitions (a quantifier and a qualifier ion for each compound), which adds extra confirmation not included in the original Method 1694. Finally, we verify, for the first time, EPA Method 1694 on water samples collected in several locations in Colorado, where positive identifications for several pharmaceuticals were found. This study is a valuable indicator of the potential of LC/MS–MS for routine quantitative multi-residue analysis of pharmaceuticals in drinking water and wastewater samples and will make monitoring studies much easier to develop for water utilities across the US, who are currently seeking guidance on analytical methods for pharmaceuticals in their water supplies.
This paper describes the use of the relative isotopic mass defect, which is the mass defect between the monoisotopic mass of an element and the mass of its A + 1 or its A + 2 isotopic cluster. The ...relative isotopic mass defect is combined with the intensity of the isotopic cluster and a formula generator to find the correct molecular formula for unknown pesticides, using accurate mass measurements. This paper introduces the concept of the relative mass defect of isotopes and the isotopic mass average (IMA), especially for C, H, N, O, S, Cl, and Br, and how to correlate these measurements to the correct molecular formula of an unknown compound. A heuristic rule of ±3 × 10⁻³ u (+3 millimass units) is developed as a simple observational tool for viewing accurate mass data with four-decimal-place mass accuracy. This heuristic rule allows one to rapidly scan data “by eye” without the use of sophisticated software, and is a useful and rapid way of examining a molecular formula.
In recent years, the presence of pharmaceuticals in the aquatic environment has been of growing interest. These new contaminants are important because many of them are not degraded under the typical ...biological treatments applied in the wastewater treatment plants and represent a continuous input into the environment. Thus, compounds such as diclofenac are present in surface waters in all Europe and a crucial need for more enhanced technologies that can reduce its presence in the environment has become evident. In this sense, advanced oxidation processes (AOPs) represent a good choice for the treatment of hazardous nonbiodegradable pollutants. This work deals with the solar photodegradation of diclofenac, an antiinflammatory drug, in aqueous solutions by photo-Fenton reaction. A pilot-scale facility using a compound parabolic collector (CPC) reactor was used for this study. Results obtained show rapid and complete oxidation of diclofenac after 60 min, and total mineralization (disappearance of dissolved organic carbon, DOC) after 100 min of exposure to sunlight. Although diclofenac precipitates during the process at low pH, its degradation takes place in the homogeneous phase governed by a precipitation−redissolution−degradation process. Establishment of the reaction pathway was made possible by a thorough analysis of the reaction mixture identifying the main intermediate products generated. Gas chromatography−mass spectrometry (GC/MS) and liquid chromatography coupled with time-of-flight mass spectrometry (LC/TOF-MS) were used to identify 18 intermediates, in two tentative degradation routes. The main one was based on the initial hydroxylation of the phenylacetic acid moiety in the C-4 position and subsequent formation of a quinone imine derivative that was the starting point for further multistep degradation involving hydroxylation, decarboxylation, and oxidation reactions. An alternative route was based on the transient preservation of the biphenyl amino moiety that underwent a similar oxidative process of C−N bond cleavage. The proposed degradation route differs from those previously reported involving alternative degradation processes (ozonization, UV/H2O2, or photolysis), indicating that diclofenac degradation follows different pathways, depending on the treatment applied.
In this work, a new multi-residue methodology using liquid chromatography–time-of-flight mass spectrometry (LC–TOF-MS) for the quantitative (routine) analysis of 15 pesticide residues has been ...developed. The analytical performance of the method was evaluated for different types of fruit and vegetables: pepper, broccoli, tomato, orange, lemon, apple and melon. The accurate mass measurements were compared in different matrices at significantly different concentration levels (from 0.01 to 0.5
mg/kg) obtaining accuracy errors lower than 2
ppm, which is well within the accepted limits for elemental confirmation. Linearity of response over two orders of magnitude was demonstrated (
r
>
0.99). Matrix effects resulting in suppression or enhancement of the response were frequently observed, most notably in broccoli and citrus. Instrumental limits of detection (LOD) were between 0.0005 and 0.03
mg/kg depending on the commodity and pesticide studied, all being within European Union regulations for food monitoring program. Finally, the methodology was applied to the analysis of two samples from an inter-laboratory exercise. The high degree of confirmation for target pesticides by accurate mass measurements demonstrated the applicability of the method in routine analysis. This study is a valuable indicator of the potential of LC–TOF-MS for quantitative multi-residue analysis of pesticides in vegetables and fruits.
