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Anthropogenic activities and urbanization can lead to the discharge of organic compounds into surface waters. It is important to investigate these relationships further to mitigate contamination better and prioritize protection efforts. This study aimed to verify the effect of specific anthropogenic factors on lake water contamination caused by trace organic contaminants (TrOCs) such as pharmaceuticals, pesticides and consumer product additives. Data on the detection and concentration levels of 54 TrOCs, major anthropogenic land use, and human activities from a large-scale study on Canadian lakes were used to reach this goal. The association of population and livestock densities, the presence of wastewater treatment plants (WWTPs) and hospitals as well as the agricultural and urban land use in the lakes' watersheds on lake water contamination was investigated by applying negative binomial and ordinal logistic regression models. These models were also controlled for lake/watershed area ratio, lake depth, water, residence time, watershed slope, precipitation, and sampling date. The statistical analysis confirmed that agricultural land use, urban land use, and WWTPs plants in lake watersheds are significantly associated with the number of TrOCs detected (incidence rate ratio > 1, p < 0.001) and the summed concentration of targeted TrOCs (odds ratio > 1, p < 0.001). Agricultural land use (odds ratio = 1.58, p < 0.001) and urban land use (odds ratio = 1.19, p < 0.02) were also significantly associated with the summed concentration of the targeted pesticides. This latter outcome thus suggests that urban centers are also important contributors to the concentration levels of pesticides in lakes. Overall, these results demonstrate that even in complex ecosystems such as lakes, it is possible to use a limited number of factors to explain anthropogenic contamination. This can help policymakers make informed decisions on contamination mitigation and provide insights into watershed management.
The presence of trace organic contaminants (TrOCs), such as pharmaceuticals, personal care products, additives, and polar pesticides in sediments of rivers and lakes highly impacted by anthropogenic activities makes sediments a secondary source of contamination for aquatic ecosystems. Considering this, a method for analyzing 44 TrOCs of diverse nature (including five transformation products, 13 pharmaceuticals, five personal care products, 14 pesticides, and seven additives) was developed and validated. It is based on extraction by pressurized liquid extraction (PLE), followed by purification and pre-concentration by solid phase extraction (SPE) and quantification by liquid chromatography coupled to a triple quadrupole mass spectrometer (LC-QqQMS). The method was optimized according to dispersant type, temperature, and extraction solvent. The influence of organic matter in sediments on quantitative analysis was also investigated in detail. Matrix effects were highly and significantly correlated (r=-0.9146, p < 0.0001) with retention time. Using internal standards showed the best results for effectively correcting matrix effects without affecting method sensitivity. The method was then validated according to key figures of merit: linearity (R2 > 0.990), extraction recoveries (> 60 % for 34 compounds), trueness (bias % < 15 %), precision (relative standard deviation < 20 %) and matrix effects (between -13.3 % and 17.8 %). This method can be applied for routine analysis of TrOCs in different sediment matrices. The method was applied to ten lake sediment samples collected in Québec, Canada. Results demonstrated the presence of 17 compounds in at least one lake at concentrations between 0.07 to 1531 ng g-1. The reported concentrations provide a first picture of the occurrence of chemical stressors in sediments of small lake highly anthropized ecosystems in Eastern Canada.
Rationale: Rivaroxaban is an anticoagulant prescribed to patients who are at risk of medical conditions such as deep-vein thrombosis, pulmonary embolisms, and strokes caused by blood clots. The administration of this drug is monitored to adjust the dosage and evaluate patients' blood concentration. Rapid quantification of this drug in plasma could make it possible to ensure that the dose present in the blood of patients does not represent a danger for the medical intervention to be carried out. Methods: Liquid chromatography–tandem mass spectrometry is usually employed to quantify rivaroxaban in blood, plasma, and serum. Here, an alternative method of analysis based on laser diode thermal desorption–triple quadrupole mass spectrometry (LDTD-QqQMS) was developed and comprehensively validated. This new method allows the quantification of rivaroxaban in less than 13 s from sample to sample. The extraction of rivaroxaban in human serum was done by a salting-out liquid–liquid extraction with acetonitrile and a saturated sodium chloride solution. Results: The proposed method allows the quantification of rivaroxaban in less than 13 s from sample to sample. During validation, all criteria were respected. The accuracy was < 15% of the nominal value, the precision was < 15%CV, and the recovery was ⋝ 89.9%. There were no observed carryover or matrix effects. Analysis of the extracted samples established the stability of dry (24 h) and wet samples (1 week) when samples cannot be analyzed immediately, a considerable advantage in a clinical setting. Conclusions: This method improves sample throughput by more than 1200% compared to liquid chromatography–tandem mass spectrometry methods of analysis of rivaroxaban and decreases analysis costs by reducing solvent consumption and instrument time.
Numerous contaminants are produced and used daily, a significant fraction ultimately finding their way into natural waters. However, data on their distribution in lakes is lacking. To address this gap, the presence of 54 trace organic contaminants (TrOCs), representative of various human activities, was investigated in the surface water of 290 lakes across Canada. These lakes ranged from remote to highly impacted by human activities. In 88% of the sampled lakes, contaminants were detected, with up to 28 detections in a single lake. The compounds most frequently encountered were atrazine, cotinine, and deethylatrazine, each of which was present in more than a third of the lakes. The range of detected concentrations was from 0.23 ng/L to about 2200 ng/L for individual compounds, while the maximum cumulative concentration exceeded 8100 ng/L in a single lake. A risk assessment based on effect concentrations for three aquatic species (Pimephales promelas, Daphnia magna, and Tetrahymena pyriformis) was conducted, revealing that 6% of lakes exhibited a high potential risk for at least one species. In 59% of lakes, some contaminants with potential sub-lethal effects were detected, with the detection of up to 17 TrOCs with potential impacts. The results of this work provide the first reference point for monitoring the evolution of contamination in Canadian lakes by TrOCs. They demonstrate that a high proportion of the sampled lakes bear an environmentally relevant anthropogenic chemical footprint.
The objective of this study was to integrate passive sampling with targeted analysis to quantify known contaminants of emerging concern (CECs) and, with non-targeted analysis. to identify previously unknown water-soluble compounds. Polar Organic Chemical Integrative Samplers (POCIS) were deployed in the treated effluent of a wastewater treatment plant serving the City of Hamilton, ON, Canada, as well as at three stations in Hamilton Harbour and at nearshore locations in Lake Ontario. Targeted analysis indicated that there was a gradient of pharmaceuticals, caffeine, and artificial sweeteners from highest levels in wastewater to lowest levels in the harbour furthest from the wastewater discharge. The estimated concentrations of current use pesticides were highest in the central part of the harbour. Pooled POCIS extracts were also analyzed using high-resolution quadrupole-time-of-flight mass spectrometry and the exact mass data generated were screened using a pattern recognition application. The greatest number of features were detected in positive ion mode from POCIS deployed in the central part of the harbour, and so exact mass data from this station were further evaluated using the Global Natural Products Social Molecular Networking data base. Novel CECs tentatively identified included pharmaceuticals from the angiotensin receptor blocker class. Follow-up targeted analysis confirmed that a tire wear compound, hexamethoxymethylmelamine (HMMM), the coal-tar derived compound, lepidine, the anticonvulsant, lamotrigine and a metabolite of a cough suppressant, dextrorphan, were present in POCIS. We propose that this approach be part of a Great Lakes Early Warning System to identify emerging threats from chemical contaminants.
In Canada studies on the presence of trace organic contaminants (TrOCs) such as pharmaceuticals, personal care products, pesticides and flame retardants in lakes have primarily focused on the water column at localized scales. To address this gap, the occurrence of 44 TrOCs, representative of various types of human activities, was investigated in surface sediments (0–2 cm) from 193 lakes across Canada. A total of 28 targeted TrOCs were detected, with 99.5 % of the samples containing at least one detection, and one lake exhibiting up to 12 detections. The most frequently detected contaminants (> 20 % of samples) were the insect-repellent diethyltoluamide (DEET), the UV filter oxybenzone, the flame retardants tris(2-butoxyethyl) phosphate (TBEP), tris(2-chloroethyl) phosphate (TCEP), and triphenyl phosphate (TPP), the stimulant caffeine, and cotinine, a metabolite of the stimulant nicotine. Median reported concentrations of the targeted TrOCs ranged from 0.017 pg g−1 to 359 ng g−1, with a maximum value of 23,700 ng g−1 observed for DEET in one lake.
The geographic distribution of analyte concentrations varied by compound class: pharmaceuticals and consumer product additives were predominantly found in the more urbanized regions of Ontario and Quebec, whereas personal care products such as DEET and oxybenzone were more frequently detected in the western provinces of Canada. An environmental risk assessment based on an additive model conducted on three aquatic organisms (algae, cladocerans, and fish) revealed that 4 % and 6 % of the lakes posed a potentially high risk for cladocerans and algae, respectively. A geographical analysis indicated that lakes in the south of the eastern provinces of Canada presented the highest risks for all three species.
These findings represent the first large-scale results detailing the extent of contamination caused by TrOCs on Canadian lake sediments. They establish reference levels that can guide future monitoring efforts and inform policy discussions aimed at protecting lake ecosystems.
2019-2023
In Daphnia magna, 20-hydroecdysone (20E) is the main molting hormone and its metabolism is of interest to identify new biomarkers of exposure to contaminants. The present study aimed to: i) assess baseline levels of 20E and transcription levels of four related-genes (shade, neverland, ultraspiracle and ecdysteroid receptor); and ii) evaluate effects in D. magna after 21 days of exposure to fenarimol (anti-ecdysteroid) and a mixture of gemfibrozil and clofibric acid (lipid-lowering drugs) at sublethal concentrations. Endpoints included transcription of the target genes and quantification of 20E, mortality and reproduction of daphnids. Baseline results showed that average responses were relatively similar and did not vary more than 2-fold. However, intra-day variation was generally high and could be explained by sampling individuals with slightly different stages of their development. Exposure tests indicated a significant decrease in daphnid reproduction following chronic exposure to a concentration of 565 µg/L of fenarimol. However, no difference was observed between the control and exposed groups for any of the investigated genes, nor for the levels of 20E after 21 days of exposure. Following exposition to gemfibrozil and clofibric acid at 1 µg/L, no changes were observed for the measured parameters. These results suggest that changes in transcription levels of the target genes and concentrations of 20E may not be sensitive endpoints that can be used as biomarkers of sublethal exposure to the target compounds in D. magna. Measuring multiple time points instead of a single measure as well as additional molecular endpoints obtained from transcriptomic and metabolomic studies could afford more insights on the changes occurring in exposed daphnids to lipid-altering compounds and identify efficient biomarkers of sublethal exposure.
The bioremediation of pharmaceutical compounds contained in wastewater, in an ecological and sustainable way, is possible via the oxidative action of fungal laccases. The discovery of new fungal laccases with unique physico-chemical characteristics pushes researchers to identify suitable laccases for specific applications. The aim of this study is to purify and characterize laccase isoenzymes produced from the Trametes hirsuta IBB450 strain for the bioremediation of pharmaceutical compounds. Two main laccases mixtures were observed and purified in the extracts and were called Yn and Yg. Peptide fingerprinting analysis suggested that Yn was constituted mainly of laccase Q02497 and Yg of laccase A0A6M5CX58, respectively. Robustness tests, based on tolerance and stability, showed that both laccases were affected in a relatively similar way by salts (KCl, NaCl), organic solvents (ACN, MeOH), denaturing compounds (urea, trypsin, copper) and were virtually unaffected and stable in wastewater. Determination of kinetic constants (Michaelis (KM), catalytic constant (kcat) and kinetic efficiency (K=kcat/KM)) for the transformation of synthetic hormone 17-ethynylestradiol and the anti-inflammatory agent diclofenac indicates a lower KM and kcat for laccase Yn but relative similar K constant compared to Yg. Synergistic effects were observed for the transformation of diclofenac, unlike 17alpha-ethynylestradiol. Transformation studies of 17alpha-ethynylestradiol at different temperatures (4 and 21 °C) indicate a transformation rate reduction of approximately 75-80% at 4 °C against 25% for diclofenac in less than an hour. Finally, the classification of laccases Yg and Yn into one of eight groups (group A-H) suggests that laccase Yg belongs to group A (constitutive laccase) and laccase Yn belongs to group B (inducible laccase).
Targeted mass spectrometry is extensively used for the quantitative measurement ofvarious molecules present in complex matrices. It is certainly one of the most impor-tant analytical duties in a mass spectrometry laboratory. Systematic development ofselected-reaction monitoring (SRM), multiple-reaction monitoring (MRM) andparallel-reaction monitoring (PRM) methods for targeted mass spectrometry-basedanalysis was performed without considering future opportunities. The advancementof hardware and software technologies has resulted in greater resolution, accuracy,speed and depth. For sure, SRM, MRM or PRM acquisitions can quantify moleculesvery accurately at trace levels. However, they do not provide datasets allowing futuredata mining. Obviously, we cannot truly quantify something that we do not know isthere. However, using non-targeted data acquisition for target analysis, we can gen-erate a MS1and MS2digital libraries of each sample, providing future proof datasets.This is instrumental for data mining following new questions potentially arising intime permitting new and deeper processing and interpretation. This perspectivearticle provides thoughts on why we believe it is time to question the status quo intargeted mass spectrometry.
Rationale: The COVID-19 pandemic demonstrated the importance of high-throughput analysis for public health. Given the importance of surface viral proteins for interactions with healthy tissue, they are targets of interest for mass spectrometry-based analysis. For that reason, the possibility of detecting and quantifying peptides using a high-throughput technique, laser diode thermal desorption-triple quadrupole mass spectrometry (LDTD-QqQMS), was explored. Methods: Two peptides used as models for small peptides (leu-enkephalin and endomorphin-2) and four tryptic peptides (GVYYPDK, NIDGYFK, IADYNYK, and QIAPGQTGK) specific to the SARS-CoV-2 Spike protein were employed. Target peptides were analyzed individually in the positive mode by LDTD-QqQMS. Peptides were quantified by internal calibration using multiple reaction monitoring transitions in pure solvents and in samples spiked with 20 g mL-1 of a bovine serum albumin tryptic digest to represent real analysis conditions. Results: Low energy fragment ions (b- and y- ions) as well as high-energy fragment ions (c- and x-ions) and some of their corresponding water or ammonia losses were detected in the full mass spectra. Only for the smallest peptides, leu-enkephalin and endomorphin-2, [M+H]+ ions were observed. Product ion spectra confirmed that, with the experimental conditions used in the present study, LDTD transfers a considerable amount of energy to the target peptides. Quantitative analysis showed that it was possible to quantify peptides using LDTD-QqQMS with acceptable calibration curve linearity (R2>0.99), precision (RSD<18.2%), and trueness (bias<8.3%). Conclusions: This study demonstrated for the first time that linear peptides can be qualitatively and quantitatively analyzed by LDTD-QqQMS. Limits of quantification and dynamic ranges are still inadequate for clinical applications, but other applications where higher levels of proteins must be detected, could be possible by LDTD. Given the high-throughput capabilities of LDTD-QqQMS (> 15000 in less than 43 h), more studies are needed to improve the sensitivity for peptide analysis of this technique.
In the environment, synthetic polymers, commonly known as “plastics” are well-known to undergo various chemical weathering processes which modify their surface chemistry by introducing new functional groups. Such changes are important to monitor, as they can severely influence the toxicity caused by plastic debris. Therefore, in this study, two chemometric models are proposed to accelerate the chemical classification of macro and mesoplastics found in the environment. For this purpose, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied on preprocessed infrared spectra of 83 plastic fragments found in public lake and river beaches. HCA associated all beach samples to a known plastic whereas PCA enabled the association of only 39.8% (33 out of 83) of the beach samples to a known plastic. However, both techniques agreed on 93.9% of the samples identified. According to PCA and HCA results, polypropylene and polyethylene were the most frequently identified polymers in the samples. PCA turned out to be a very promising tool for fast screening of weathered plastics, since distance of samples from the polypropylene cluster in the PCA plot was correlated to weathering. This was later confirmed by employing other characterization techniques such as micro-Raman, x-ray photoelectron spectroscopy and scanning electron microscopy. Finally, future experiments should focus on the applicability of the proposed combined chemometric approach for very small microplastics (smaller than 100 µm), as they have more important effects than larger plastics on aquatic ecosystems.
Over 350,000 compounds are registered for production and use including a high number of congeners found in complex chemical mixtures (CCMs). With such a high number of chemicals being released in the environment and degraded into transformation products (TPs), the challenge of identifying contaminants by non-targeted screening (NTS) is massive. “Bottom-up” studies, where compounds are subjected to conditions simulating environmental degradation to identify new TPs, are time consuming and cannot be relied upon to study the TPs of hundreds of thousands of compounds. Therefore, the development of “top-down” workflows, where the structural elucidation of unknown compounds is carried directly on the sample, is of interest. In this study, a top-down NTS workflow was developed using molecular networking and clustering (MNC). A total of 438 compounds were identified including 176 congeners of consumer product additives and 106 TPs. Reference standards were used to confirm the identification of 53 contaminants among them lesser-known pharmaceuticals (aliskiren, sitagliptin) and consumer product additives (lauramidopropyl betaine, 2,2,4-trimethyl-1,2- dihydroquinoline). The MNC tools allowed to group similar TPs and congeners together. As such, several previously unknown TPs of pesticides (metolachlor) and pharmaceuticals (gliclazide, irbesartan) were identified as tentative candidates or probable structures. Moreover, some congeners that had no entry on global repositories (PubChem, ChemSpider) were identified as probable structures. The workflow worked efficiently with oligomers containing ethylene oxide moieties, and with TPs structurally related to their parent compounds.
In this study, photodegradation experiments simulating the exposure conditions of sunlight on the commonly detected in surface and wastewater contaminants atorvastatin (ATV), bezafibrate (BEZ), oxybenzone (OXZ), and tris(2-butoxyethyl)phosphate (TBEP) were conducted as the fate of these compounds and their transformation products (TPs) was followed. Then a nontargeted analysis was carried out on an urban river to confirm the environmental occurrence of the TPs after which the ECOSAR software was used to generate predicted effect levels of toxicity of the detected TPs on aquatic organisms. Five TPs of ATV were tentatively identified including two stable ones at the end of the experiment: ATV_TP557a and ATV_TP575, that were the product of hydroxylation. Complete degradation of OXZ was observed in the experiment with no significant TP identified. BEZ remained stable and largely undegraded at the end of the exposure. Five TPs of TBEP were found including four that were stable at the end of the experiment: TBEP_TP413, TBEP_TP415, TBEP_TP429, and TBEP_TP343. In the nontargeted analysis, ATV_TP557b, a positional isomer of ATV_TP557a, ATV_TP575 and the 5 TPs of TBEP were tentatively identified. The predicted concentration for effect levels were lower for ATV_TP557b compared to ATV indicating the TP is potentially more toxic than the parent compound. All the TPs of TBEP showed lower predicted toxicity toward aquatic organisms than their parent compound. These results highlight the importance of conducting complete workflows from laboratory experiments, followed by nontargeted analysis to confirm environmental occurrence to end with predicted toxicity to better communicate concern of the newfound TPs to monitoring programs.
A method based on gas chromatography (GC) coupled with electron ionization mass spectrometry (EI-MS) employing N,O-bis(trimethylsilyl)trifluoroacetamide with trimethylchlorosilane (BSTFA + 1% TMCS) as derivatization agent was developed to quantify short-chain carboxylic acids (C1-C6) in hospital wastewater treated by wet air oxidation, an advanced oxidation process. Extraction from water and derivatization of volatile and semi-volatile short chain carboxylic acids were optimized and validated and limits of quantification (LOQ = 0.049 mg/L - 4.15 mg/L), repeatability (RSD = 1.7 % – 12.8 %), recovery (31 - 119 %) and trueness (relative bias = -19.0 % – 3.4%) were acceptable. The validated method was successfully applied to monitor the concentration of organic acids formed after wet air oxidation of water samples. Results showed that the method described herein allowed to identify 38 % and up to 46 % of the final COD chemical composition after wet air oxidation of acetaminophen spiked in deionised water and hospital wastewater samples, respectively. The developed method also allowed to perform qualitative non-targeted analysis in hospital wastewater samples after treatment. Results demonstrated that glycerol, methenamine, and benzoic acid were also present in the samples and their presence was confirmed with reference standards.
Removal of pharmaceuticals from wastewater using chemical processes is a promising solution to mitigate pollution in drinking and surface waters. Non-catalytic wet air oxidation (WAO) is a highly efficient advanced oxidation process that uses air and water at high temperatures and pressures to remove high concentrations of organic compounds from various wastes without use of catalysts. However, the elimination of pharmaceuticals in hospital wastewater with a low organic content by WAO has not yet been sufficiently studied. The objective of the present study was to evaluate both the efficiency and costs of WAO treatment to remove pharmaceuticals present in hospital effluents. First, a laboratory-scale WAO batch unit was used to optimize oxidation temperatures and residence times to achieve high elimination of ten pharmaceuticals of interest in spiked deionized water. Then, optimal conditions were applied to treat hospital wastewater effluents. Results showed that even at low chemical oxygen demand values (less than 600 mg O2 per L), WAO at 290 °C with 15 min residence time removed between 95.0% and 99.1% of the target compounds spiked at 10 μg/L in hospital wastewater. Acute toxicity bioassays using the crustacean Daphnia magna and the bacterium Aliivibrio fischeri showed that the toxicity of hospital wastewater increased after WAO treatment due to the generation of transformation products. However, since the intended use of WAO is as pretreatment for hospital effluents before municipal water treatment, it is not yet clear if WAO treated effluents could affect bacteria in activated sludge. The study included a technoeconomic analysis to evaluate capital expenditures (CAPEX) and operational expenditures (OPEX) of an industrial-scale WAO unit to remove pharmaceuticals from the wastewater effluent of a local hospital. This analysis demonstrated that CAPEX for an 86 L/min WAO industrial-scale unit was $ 2.35 M (in Canadian dollars), while OPEX was $ 1.09 M, which corresponds to a relative price of $ 27 per m3. Initial investment for the WAO unit might be reduced by up to 44% by employing a preconcentration unit to increase the effluents chemical oxygen demand in smaller volumes which could also make the process autothermal while reducing WAO operating expenses by more than 20%.
Non-targeted screening (NTS) in mass spectrometry (MS) helps alleviate the shortcoming of targeted analysis such as missing the presence of concerning compounds that are not monitored and its lack of retrospective analysis to subsequently look for new contaminants. Most NTS workflows include high resolution tandem mass spectrometry (HRMS2) and structure annotation with libraries which are still limited. However, in silico combinatorial fragmentation tools that simulate MS2 spectra are available to help close the gap of missing compounds in empirical libraries. Three NTS tools were combined and used to detect and identify unknown contaminants at ultra-trace levels in surface waters in real samples in this qualitative study. Two of them were based on combinatorial fragmentation databases, MetFrag and the Similar Partition Searching algorithm (SPS), and the third, the Global Natural Products Social Networking (GNPS), was an ensemble of empirical databases. The three NTS tools were applied to the analysis of real samples from a local river. A total of 253 contaminants were identified by combining all three tools: 209 were assigned a probable structure and 44 were confirmed using reference standards. The two major classes of contaminants observed were pharmaceuticals and consumer product additives. Among the confirmed compounds, octylphenol ethoxylates, denatonium, irbesartan and telmisartan are reported for the first time in surface waters in Canada. The workflow presented in this work uses three highly complementary NTS tools and it is a powerful approach to help identify and strategically select contaminants and their transformation products for subsequent targeted analysis and uncover new trends in surface water contamination.
The laser diode thermal desorption (LDTD) ionization source allows ultrafast and sensitive analysis of small molecules by mass spectrometry. Signal enhancement in LDTD has been observed when coating the surface of sample microwells with a solution of ethylenediaminetetraacetic acid (EDTA) or nitrilotriacetic acid. Here we present a quantitative analysis of signal enhancement using solutions of diverse commercial proteins (lysozyme, immunoglobulin G, albumin, and fibrinogen) as coatings. Results showed that compounds with polar chemical functions such as carboxylic acid, sulfonyl, and nitro had signal enhancement factors, in most cases higher than 10, when using any of the tested proteins as coating agent. Analysis of variance revealed that immunoglobulin G and fibrinogen gave the best results. However, the signal enhancement factors obtained with these proteins were not superior to those observed with EDTA. To explain the signal enhancement effect of proteins, analysis by scanning electron microscopy of dried samples on the microwell sample plates was carried out. Images showed that salicylic acid, one of the compounds with the highest observed signal enhancement, formed a thick layer when applied directly on the uncoated surface, but it formed small crystals (smaller than 1 μm) in the presence of protein or EDTA coatings. Further crystallographic studies using powder X‐ray diffraction showed that the crystalline form of salicylic acid is modified in the presence of EDTA. Salicylic acid when mixed with EDTA had a higher percentage of amorphous phase (38.1%) than without EDTA (23.1%). These results appear to confirm that the diminution of crystal size of analytes and the increase of amorphous phase are implicated in signal enhancement effect observed in LDTD using microwell surface coatings. To design better coatings and completely elucidate the signal enhancement effect in LDTD, more studies are necessary to understand the effects of coatings on the ionization of analytes.
The distribution and quality of water resources vary dramatically across Canada, and human impacts such as land-use and climate changes are exacerbating uncertainties in water supply and security. At the national level, Canada has no enforceable standards for safe drinking water and no comprehensive water-monitoring program to provide detailed, timely reporting on the state of water resources. To provide Canada's first national assessment of lake health, the NSERC Canadian Lake Pulse Network was launched in 2016 as an academic-government research partnership. LakePulse uses traditional approaches for limnological monitoring as well as state-of-the-art methods in the fields of genomics, emerging contaminants, greenhouse gases, invasive pathogens, paleolimnology, spatial modelling, statistical analysis, and remote sensing. A coordinated sampling program of about 680 lakes together with historical archives and a geomatics analysis of over 80,000 lake watersheds are used to examine the extent to which lakes are being altered now and in the future, and how this impacts aquatic ecosystem services of societal importance. Herein we review the network context, objectives and methods.
Laser-diode thermal desorption (LDTD) is an ionization source usually coupled to triple quadrupole mass spectrometry (QqQMS) and specifically designed for laboratories requiring high-throughput analysis. It has been observed that surface coatings on LDTD microwell plates can improve the sensitivity of the analysis of small polar molecules. The objective of the present study is to understand and quantify the effect of microwell surface coatings on signal intensity of small organic molecules of clinical, environmental, and forensic interest. Experiments showed that the peak areas of diclofenac, chloramphenicol, salicylic acid, and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol obtained by LDTD-QqQMS increased by up to 3 orders of magnitude when using microwells coated with ethylenediaminetetraacetic acid (EDTA). Tests with different chelating agents and polytetrafluoroethylene as microwell surface coatings showed that nitrilotriacetic acid gave significantly higher peak areas for five out of the nine compounds that showed signal enhancement using chelating agents as coatings. Scanning electron microscopy studies of EDTA‐coated and uncoated microwells showed that analytes deposited in the former formed more uniform and thinner films than in the latter. The enhancement effect of surface coatings in LDTD‐QqQMS was explained mainly by the formation of homogenous and thinner layers of nanocrystals of analytes that are easier to desorb thermally than the layers formed when the analytes dry in direct contact with the bare stainless‐steel surface. Chemisorption of some analytes to the stainless‐steel surface of the microwell plate appeared to be a minor factor. Surface coatings widen the number of compounds analyzable by LDTD‐QqQMS and can also improve sensitivity and limits of detection.
The performance of a suspect screening method to detect diverse small-molecule trace organic contaminants (TOCs) was systematically evaluated using a set of 39 model compounds. The suspect screening method used a commercial algorithm for peak identification based on liquid chromatography-high resolution mass spectrometry data. Experiments showed that ionization efficiency, ion transfer parameters and chromatography could affect the detection of TOCs. As expected, compounds with low ionization yields and poorly retained compounds in chromatographic columns are more difficult to identify in the samples at environmental concentrations. Similarly, TOCs with large deviations from the average mass of the compounds screened were not transmitted efficiently in the mass spectrometer thus negatively affecting their detection. The suspect screening method was validated in terms of recovery and limits of identification of the model compounds using three different types of solid-phase extraction cartridges (reversed-phase with polar groups, mixed-mode anion exchange and mixed mode cation exchange). Experiments showed that more than two thirds of the model compounds had recoveries > 75% with each of the three cartridges and comparison of limits of identification showed that more than half of the model compounds could be identified at concentrations between 6 and 100 ng/L. However, it was observed that the amount of co-extracted compounds was higher in mixed-mode ion exchangers compared to the reversed-phase cartridge. Application of the suspect screening method using the three different cartridges to surface water samples showed that between 0 to 3% of the positive matches found by the peak identification algorithm were classified as probable structures. Solutions to improve suspect screening of TOCs are proposed and discussed.
2013-2018
A transformation product of trimethoprim, a contaminant of emerging concern in the environment, is generated using an electro-assisted Fenton reaction and analyzed using differential mobility spectrometry (DMS) in combination with MS/MS techniques and quantum chemical calculations to develop a rapid method for identification. DMS is used as a prefilter to separate positional isomers prior to subsequent identification by mass spectrometric analyses. Collision induced dissociation of each DMS separated species is used to reveal fragmentation patterns that can be correlated to specific isomer structures. Analysis of the experimental data and supporting quantum chemical calculations show that methylene-hydroxylated and methoxy-containing phenyl ring hydroxylated transformation products are observed. The proposed methodology outlines a high-throughput technique to determine transformation products of small molecules accurately, in a short time and requiring minimal sample concentrations (<25 ng/mL).
A new method for the measurement of accurate masses using direct infusion in an electrospray-triple quadrupole mass spectrometer is presented and compared to the traditional method using high-resolution mass spectrometry. The proposed method uses internal calibrants and post-acquisition calibration of the mass spectrum signal using the MassWorks software to determine accurate masses. Then, based on parameters such as elemental composition, number of double bond equivalents, and type of ion (even- or odd-electron), etc., a list of potential molecular formula candidates are generated and ranked according to spectral accuracy, (i.e., similarity between the calibrated profile and theoretical isotopic patterns). Experiments using six diverse synthesis products showed that mass accuracy in the Quattro Premier triple quadrupole mass spectrometer (QqQMS) was ≤9.2 mDa and spectral accuracy was ≥90.6%. According to both mass accuracy tolerance (±10 mDa) and spectral accuracy, the correct molecular formula was ranked in the top seven compounds out of up to 32 potential candidates. When considering the context of the synthesis reaction, only one formula was possible. In summary, results showed that the measurement of spectral accuracy in a low-resolution instrument such as the triple quadrupole was strongly dependent on the signal intensity and the presence of interfering peaks in the profile mass range window. This study suggests that use of triple quadrupole mass spectrometry followed by post-acquisition calibration can be an economical and robust approach compared to the traditional method using high-resolution mass spectrometers for the measurement of accurate masses in routine applications using small organic molecules at microgram-per-litter concentrations in relatively clean matrices.
The study of the fate of emerging organic contaminants (EOCs), especially the identification of transformation products, after water treatment or in the aquatic environment, is a topic of growing interest. In recent years, electrochemistry coupled to mass spectrometry has attracted a lot of attention as an alternative technique to investigate oxidation metabolites of organic compounds. The present study used different electrochemical approaches, such as cyclic voltammetry, electrolysis, electro-assisted Fenton reaction coupled offline to high resolution mass spectrometry and thin-layer flow cell coupled online to high resolution mass spectrometry, to study oxidation products of the anti-infective trimethoprim, a contaminant of emerging concern frequently reported in wastewaters and surface waters. Results showed that mono- and di-hydroxylated derivatives of trimethoprim were generated in electrochemically and possibly tri-hydroxylated derivatives as well. Those compounds have been previously reported as mammalian and bacterial metabolites as well as transformation products of advance oxidation processes applied to waters containing trimethoprim. Therefore, this study confirmed that electrochemical techniques are relevant not only to mimic specific biotransformation reactions of organic contaminants, as it has been suggested previously, but also to study the oxidation reactions of organic contaminants of interest in water treatment. The key role that redox reactions play in the environment make electrochemistry-high resolution mass spectrometry a sensitive and simple technique to improve our understanding of the fate of organic contaminants in the environment.
In this experiment, students develop their knowledge of mass spectrometry to identify dyes in different commercial pen ink entries on paper using a simple method based on liquid-solid extraction and high-resolution mass spectrometry. In short, students will first extract the dyes in the ink from the paper with a 1:1 solution of water and methanol. The sample is then analyzed by matrix assisted laser desorption/ionization quadrupole time-of-flight mass spectrometer (MALDI-QTOFMS). Inks from three commercial inks were analyzed and they could be differentiated according to the presence of peaks in the mass spectrum corresponding to specific dyes. Key concepts in mass spectrometry such as resolution, mass accuracy and formula determination can be taught with the acquired data. A forensic activity could also be added to enhance the interest of students for mass spectrometry and its applications. This laboratory experiment is expected to be performed in a four-hour laboratory period by sophomore or junior students. To summarize, this experiment provides an interesting introduction to fundamental concepts of mass spectrometry.
Correct identification of a chemical substance in environmental samples based only on accurate mass measurements can be difficult especially for molecules >300 Da. Here is presented the application of spectral accuracy, a tool for the comparison of isotope patterns toward molecular formula generation, as a complementary technique to assist in the identification process of organic micropollutants and their transformation products in surface water. A set of nine common contaminants (five antibiotics, an herbicide, a beta-blocker, an antidepressant, and an antineoplastic) frequently found in surface water were spiked in methanol and surface water extracts at two different concentrations (80 and 300 μg L–1). They were then injected into three different mass analyzers (triple quadrupole, quadrupole-time-of-fight, and quadrupole-orbitrap) to study the impact of matrix composition, analyte concentration, and mass resolution on the correct identification of molecular formulas using spectral accuracy. High spectral accuracy and ranking of the correct molecular formula were in many cases compound-specific due principally to conditions affecting signal intensity such as matrix effects and concentration. However, in general, results showed that higher concentrations and higher resolutions favored ranking the correct formula in the top 10. Using spectral accuracy and mass accuracy it was possible to reduce the number of possible molecular formulas for organic compounds of relative high molecular mass (e.g., between 400 and 900 Da) to less than 10 and in some cases, it was possible to unambiguously assign one specific molecular formula to an experimental isotopic pattern. This study confirmed that spectral accuracy can be used as a complementary diagnostic technique to improve confidence levels for the identification of organic contaminants under environmental conditions.
Both free carbohydrates and hemicelluloses from green sweet sorghum [Sorghum bicolor (L.) Moench] were extracted using a steam process to produce combined first and second generation ethanol. Once the carbohydrates removed, Soxhlet extraction was used to extract the lipophilic secondary metabolites from the plant fibers and the results were compared to those obtained with the biomass extracted without prior steam treatments. This allowed assessing if the carbohydrate removal process had an impact on the secondary metabolites that could be recovered from the biomass. Soxhlet extracts where characterized using several techniques such as gas chromatography-mass spectrometry, liquid chromatography-triple quadrupole mass spectrometry and liquid chromatography-UV detection followed by high-resolution mass spectrometry. A total of 13 compounds were detected and quantified in the non-polar soxhlet fraction and were mainly fatty acids (6), phenyl glycosides (5) and sterols (2) at concentrations ranging between 0.015 g kg−1 and 1.5 g kg−1 (dry biomass). Comparison of the extractive content before and after steam process showed that most of the compounds were found in a lesser extent (up to 71%) although still recoverable after the steam process while other compounds (namely phytosterols) were as concentrated as they were prior to steam treatments. These results show that in the case of sweet sorghum, the preliminary extraction of the carbohydrate content with a steam process may not completely hinder the possibility to extract high value secondary metabolites, which would in this case come second in a biorefinery approach.
To improve the certainty that a specific small organic molecule has been detected in a given sample by high-resolution mass spectrometry, other techniques that give conclusive evidence about the chemical structure of a compound like nuclear magnetic resonance or complementary information on its composition such as hydrogen–deuterium exchange (HDX) are often necessary. This study presents a systematic investigation that aims to improve the applicability of post-column HDX for those purposes. Key parameters like mobile-phase flow rates, volume percentage of H2O in the mobile phase, and D2O addition flow rates were optimized to provide an isotopic pattern that allows the accurate determination of the number of exchangeable hydrogen atoms in small organic molecules. A loop injection setup was used to emulate chromatographic conditions in the optimization process, and trimethoprim, a widely used anti-infective, was used as test compounds for the experiments. As expected, results showed that deuteration percentage decreased with a higher mobile-phase flow rate and increased with higher D2O flow rate. The post-column HDX technique was then validated with extracts of samples of river water and plants separated by liquid chromatography in hydrophilic interaction or reversed-phase modes. Mass spectra showed a completely visible isotopic pattern that allowed assessing correctly and unambiguously the number of exchangeable hydrogens in the compounds of interest. This study shows that post-column HDX can be used as a complementary technique to identify unknown small organic molecules in complex matrices. The current paper proposes an efficient, cost-effective,versatile technique of HDX that is helpful to assign a unique structure to a given high-resolution mass spectrometry signal.
Contamination of the aquatic environment by pharmaceuticals via urban effluents iswell known. Several classes of drugs have been identified inwaterways surrounding these effluents in the last 15 years. To better understand the fate of pharmaceuticals in ecosystems, degradation processes need to be investigated and transformation productsmust be identified. Thus, this study presents the first comparative study between three different natural environmental conditions: photolysis and biodegradation in aerobic and anaerobic conditions both in the dark of diclofenac and sulfamethoxazole, two common drugs present in significant amounts in impacted surface waters. Results indicated that degradation kinetics differed depending on the process and the type of drug and the observed transformation products also differed among these exposure conditions. Diclofenac was nearly degraded by photolysis after 4 days, while its concentration only decreased by 42% after 57 days of exposure to bacteria in aerobic media and barely 1% in anaerobic media. For sulfamethoxazole, 84% of the initial concentration was still present after 11 days of exposure to light, while biodegradation decreased its concentration by 33% after 58 days of exposure under aerobic conditions and 5% after 70 days of anaerobic exposure. In addition, several transformation products were observed and persisted over time while others degraded in turn. For diclofenac, chlorine atoms were lost primarily in the photolysis, while a redox reaction was promoted by biodegradation under aerobic conditions. For sulfamethoxazole, isomerization was favored by photolysis while a redox reaction was also favored by the biodegradation under aerobic conditions. To summarize this study points out the occurrence of different transformation products under variable degradation conditions and demonstrates that specific functional groups are involved in the tested natural attenuation processes. Given the complexity of environmental samples more analytical effort is needed to fully identify new products of potential toxicity.
Quantification of ecdysteroids and retinoic acids at picograms per individual is typically achieved with radioimmunoassay methods. However, those methods cannot identify individual types of ecdysteroids or provide an absolute concentration, which poses problems for comparative assays such as the metabolic profiling approach for toxicity testing. The method described in the present paper, based on liquid chromatography-electrospray ionization-triple quadrupole mass spectrometry, was developed to allow the quantification in whole daphnids extracts of ecdysteroids (20-hydroxyecdysone, ecdysone, ponasterone A) and retinoic acid (sum of isomers). This approach avoids having to perform the difficult task of sampling the haemolymph on small organism(less than 5 mm). Recoveries, evaluated at three concentrations in matrix blank fortified samples, ranged from 83 to 119% for ecdysteroids and from 144 to 155% for retinoic acids. Precision (2.4–14.2%) and accuracy (−41.7 to 14.5%) were reproducible and stable over three quality control concentrations. The described liquid chromatography-triple quadrupole mass spectrometry method achieved quantification limits ranging from 210 to 380 pg mL−1 for ecdysteroids and 5 ng mL−1 for retinoic acids in spiked matrix blanks. 20-hydroxyecdysone was quantified in Daphnia magna adults (19 ± 8 pg ind−1) and juveniles (3.6 ± 1.0 pg ind−1), but was below the limit of quantification in neonates (≈0.19 pg ind−1). Ecdysone was also detected in adult specimens (≈1.8 pg ind−1).
The concentrations of 17 drugs of abuse, including cocaine, several amphetamines, opioid drugs, and 2 metabolites—benzoylecgonine, a metabolite of cocaine, and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrolidine, a metabolite of methadone—were investigated in an urban watershed that is heavily impacted by discharges of municipal wastewater. The artificial sweetener sucralose was also monitored as a persistent tracer of contamination from municipal wastewater. Monitoring was conducted in a municipal wastewater treatment plant (WWTP) and at sites upstream and downstream of the WWTP discharge, as well as in a drinking water treatment plant (DWTP) located 19 km downstream of the WWTP discharge that withdraws raw water from the river. Drug concentrations were monitored with polar organic chemical integrative samplers deployed for 2 wk in the river and in the WWTP and DWTP. Several of the investigated compounds exhibited a decrease in concentration with distance downstream from the wastewater discharge into the river, but there was little attenuation of sucralose, cocaine, benzoylecgonine, morphine, acetylmorphine, acetylcodeine, and oxycodone. Heroin and methadone were not detected at any sample locations. Amphetamine, methamphetamine, 3,4-methylenedioxy-methamphetamine, and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrolidine were not detected in the samples collected at the drinking water intake. Many of the drugs of abuse were not removed effectively in the DWTP, including cocaine, benzoylecgonine, methylenedioxyamphetamine, ephedrine, and several prescription opioids, most probably because the DWTP was operating at or above its rated treatment capacity. These data indicate that there can be transport of drugs of abuse from wastewater sources into drinking water in urban watersheds.
We studied the nature and antimicrobial activity of ozonolysis transformation products (OTPs) of levofloxacin (LEV), a frequently detected fluoroquinolone antimicrobial in environmental waters. Two bioassays, the Kirby–Bauer test and the broth microdilution assay, were used to measure changes in the antimicrobial activity of solutions at low LEV to O3 molar ratios (2:1, 2:3 and 1:3) compared to solutions without added O3 (LEV:O3 1:0). The Kirby–Bauer test was not sensitive enough to detect significant differences in the growth inhibition zones in samples LEV:O3 2:1 and LEV:O3 1:0; however, the broth microdilution assay showed that bacterial growth inhibition was significantly lower (P < 0.001) in the solutions exposed to O3. Loss of antimicrobial activity in LEV:O3 2:1 solutions of (48 ± 16)% was in agreement with the concentration decrease of LEV of (36 ± 3)% in those same samples. A method of identification of OTPs using XCMS Online was applied to LEV:O3 2:1 and 1:0 samples and indicated the presence of an OTP of LEV of formula C18H20O5N3F, which was identified as LEV-N-oxide. The molecular structure of this compound was partially confirmed by tandem mass spectrometry experiments. This study showed that even at sub-optimal ozone doses, OTPs of higher antimicrobial activity than LEV were not formed.
The presence anti-infectives in environmental waters is of interest because of their potential role in the dissemination of anti-infective resistance in bacteria and other harmful effects on non-target species such as algae and shellfish. Since no information on global trends regarding the contamination caused by these bioactive substances is yet available, we decided to investigate the impact of income inequality between countries on the occurrence of anti-infectives in surface waters. In order to perform such study, we gathered concentration values reported in the peer-reviewed literature between 1998 and 2014 and built a database. To fill the gap of knowledge on occurrence of anti-infectives in African countries, we also collected 61 surface water samples from Ghana, Kenya, Mozambique and South Africa, and measured concentrations of 19 anti-infectives. A mixed one-way analysis of covariance (ANCOVA) model, followed by Turkey–Kramer post hoc tests was used to identify potential differences in anti-infective occurrence between countries grouped by income level (high, upper-middle and lower-middle and low income) according to the classification by the World Bank. Comparison of occurrence of anti-infectives according to income level revealed that concentrations of these substances in contaminated surface waters were significantly higher in low and lower–middle income countries (p = 0.0001) but not in upper–middle income countries (p = 0.0515) compared to high-income countries. We explained these results as the consequence of the absence of or limited sewage treatment performed in lower income countries. Furthermore, comparison of concentrations of low cost anti-infectives (sulfonamides and trimethoprim) and the more expensive macrolides between income groups suggest that the cost of these substances may have an impact on their environmental occurrence in lower income countries. Since wastewaters are the most important source of contamination of anti-infectives and other contaminants of emerging concern in the environment, it is expected that deleterious effects to the aquatic biota caused by these substances will be more pronounced in countries with inadequate wastewater and collection infrastructure. With the information currently available, we could not evaluate either the role of the receiving environment or the importance of regulatory frameworks on the occurrence of anti-infectives in surface waters. Future studies should focus on these two factors in order to better evaluate risks to aquatic ecosystems in LM&LICs. We propose that CECs such as anti-infectives could be used as a new class of environmental degradation indicators that could be helpful to assess the state of development of wastewater collection and treatment infrastructure around the world.
Due to the increased consumption of chemotherapeutic agents, their high toxicity, carcinogenicity, their occurrence in theaquatic environment must be properly evaluated. An analytical method based on online solid-phase extraction coupled to liquid chromatography-tandem mass spectrometry was developed and validated. A 1 mL injection volume was used to quantify six of the most widely used cytotoxic drugs (cyclophosphamide, gemcitabine, ifosfamide, methotrexate, irinotecan and epirubicin) in municipal wastewater. The method was validated using standard additions. The validation results in wastewater influent had coefficients of determination (R2) between 0.983 and 0.998 and intra-day precision ranging from 7 to 13% (expressed as relative standard deviation %RSD), and from 9 to 23% for inter-day precision. Limits of detection ranged from 4 to 20 ng L−1 while recovery values were greater than 70% except for gemcitabine, which is the most hydrophilic compound in the selected group and had a recovery of 47%. Matrix effects were interpreted by signal suppression and ranged from 55 to 118% with cyclophosphamide having the highest value. Two of the target anticancer drugs (cyclophosphamide and methotrexate) were detected and quantified in wastewater (effluent and influent) and ranged from 13 to 60 ng L−1. The proposed method thus allows proper monitoring of potential environmental releases of chemotherapy agents.
In this study amphetamine, methamphetamine, methylenedioxymethamphetamine (MDMA), cocaine (COC), benzoylecgonine (BE), ketamine (KET) and oxycodone (OXY) in wastewater at concentrations of 100 μgL−1 were subjected to ozone to determine their removals as a function of ozone dose and to identify significant oxidation transformation products (OTPs) produced as a result of ozonation. A method based on high resolution mass spectrometry and differential analysiswas used to facilitate and accelerate the identification and structural elucidation of the transformation products. The drug removal ranged from3 to 50% depending on the complexity of thematrix and whether a mixture or individual drugs were ozonated. Both transient and persistent oxidation transformation products were identified forMDMA, COC and OXY and their chemical formulaewere determined. Three possible structures of the persistent transformation product of MDMA (OTP-213) with chemical formula C10H16O4N, were determined based on MSn mass spectra and the most plausible structure (OTP-213a) was determined based on the chemistry of ozone. These results indicate that ozone is capable of removing drugs of abuse from wastewater to varying extents and that persistent transformation products are produced as a result of treatment.
Background: Quantitative 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). Results: A 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. Conclusion: These results indicate that the method proposed is a systematic and rapid approach to study transformation products of CECs.
2009-2012
The Vibrio fischeri bioluminescence inhibition assay (Microtox) was slightly modified to use an in-house diluent containing 2% DMSO and was successfully applied to perform a rapid toxicity screening of 24 compounds including commercial plasticizers and chemicals currently studied as potential “green” plasticizers. Comparison of the EC50 values obtained indicated that 1,3-propanediol dibenzoate (PrDDB), 1,4-butanediol dibenzoate (BDDB), and dihexyl maleate (DHM) might not be good candidates as “green” plasticizers because of their higher toxicity (EC50 < 1 mg L−1). Results also indicated that Microtox is a useful technique to better understand the effect of key structural features on the toxicity of plasticizers. Comparison of EC50 values of similar compounds having a different alkyl chain lengths indicated a decrease in toxicity of dibenzoate plasticizers with respect to increasing alkyl chain size. The Microtox technique that we adapted to test compounds having low solubility was proven to be useful to evaluate the toxicity of potential “green” plasticizers relative to commercial products. However, these results cannot be used alone to select the best candidates. The Microtox technique is complementary to biodegradation experiments and plasticizing properties tests and allows, at the development stage, the screening of a large number of potential “green” plasticizers on the basis of their relative toxicity.
The occurrence of numerous emerging contaminants such as pharmaceuticals and personal care products in the environment have been reported since they became a "hot topic" in the late 1990's. The detection of these substances in environmental waters is challenging because they are found at very low concentrations and are also structurally heterogeneous. Current analytical techniques used to detect these substances are generally designed to target only a fraction of these compounds and have not yet been adapted to the detection and the identification of unknown substances. It is however crucial to study the presence of transformation products of emerging contaminants that can be potentially found in the environment after biological or chemical degradation. New analytical techniques are thus necessary to screen for the presence of large numbers of suspect emerging contaminants and their degradation products in environmental samples. High resolution-mass spectrometry (HRMS) is a promising technique that has the potential to address the shortcomings of present analytical techniques. Past work with HRMS applied to environmental analysis showed its potential to: i) screen suspect organic contaminants in surface and drinking waters collected in several locations across Canada, ii) screen and confirm the presence of cyanotoxins in algae samples from the Saint-Lawrence River, and iii) elucidate the probable structure of ozonation transformation products of emerging contaminants such as 17α-ethinylestradiol. The advantages and disadvantages of HRMS are discussed here along with strategies proposed in order to further improve its performance.
The presence of cyanotoxins in benthic Lyngbya wollei algae samples collected in a fluvial lake along the St. Lawrence River, Canada, was investigated using a multi-toxins method. Hydrophilic interaction liquid chromatography (HILIC) and reverse phased liquid chromatography (RPLC) were coupled to triple quadrupole mass spectrometry (LC-QqQMS) for quantification and to quadrupole- time of flight mass spectrometry (LC-QqTOFMS) for screening and confirmation. The presence of two saxitoxin analogues, LWTX-1 and LWTX-6, was confirmed in benthic Lyngbya wollei algae samples. Concentration of LWTX-1 was between 209 ± 5 and 279 ± 9 μg g−1. No other targeted cyan- otoxin (such as anatoxin-a, nodularin, microcystin-LR, microcystins-RR and saxitoxin) was found in the samples. The presence of LWTX-6 was observed by using a screening approach based on an in-house database of cyanotoxins, an algorithm of identification and high resolution mass spec- trometry measurements on the precursor and product ions. This work demonstrates the need for more research on the fate of benthic cyanotoxins in aquatic ecosystems such the St. Lawrence River.
A new approach for the identification of suspect trace organic contaminants in drinking and surface waters is presented. Samples were initially analyzed using a target determination method for two con- tamination tracers, carbamazepine (CBZ) and atrazine (ATZ). This method used offline solid-phase extraction and online solid-phase extraction techniques coupled to liquid chromatography–triple quadrupole mass spectrometry to accelerate the sample preparation process and improve method performance. CBZ and ATZ were found respectively in 31% and 56% of the samples, and concentrations were usually < 20 ng L-1. These samples were re-analyzed with a similar method on a quadrupole time-of-flight mass spectrometer to identify suspect contaminants by means of exact mass measurements and isotope patterns. A database of 264 common organic contaminants was built and used in conjunction with a Molecular Feature algorithm to identify the presence of these substances in drinking and surface water collected from different sources at various locations across Canada. Several organic contaminants were identified in the samples, but only the presence of caffeine, desethylatrazine, simazine and venlafaxine could be verified by comparison to pure standards. The presence of desethylatrazine was also confirmed by MS/MS experiments. These results suggest that target analysis for tracers of organic contamination may be a helpful tool to prioritize samples which should be further screened for suspect contaminants. This study also shows that the combination of separation techniques (offline and online SPE, LC) contribute to advance the applicability of high-resolution mass spectrometry for the identification of trace organic contaminants by accelerating the preparation step, reducing complexity and increasing analyte concentrations for optimal detection.
The applicability of three different ionization techniques: atmospheric pressure photoionization (APPI), atmospheric pressure chemicalionization(APCI)andelectrosprayionization(ESI)wastestedfortheliquidchromatography-tandemmassspectrometry (LC-MS/MS) analysis of five target pharmaceuticals (cyclophosphamide, methotrexate, bezafibrate, enalapril and orlistat) in wastewater samples. Performance was compared both by flow injection analysis (FIA) and on-column analysis in deionized water and wastewater samples. A column switching technique for the on-line extraction and analysis of water samples was used. For both FIA and on-column analysis, signal intensity and signal-to-noise (S/N) ratio of the target analytes in the three sources were studied. Limits of detection and matrix effects during the analysis of wastewater samples were also investigated. ESI generated significantly larger peak areas and higher S/N ratios than APCI and APPI in FIA and in on-column analysis. ESI was proved to be the most suitable ionization method as it enabled the detection of the five target compounds, whereas APCI and APPI ionized only four compounds.
Sulfonamides are antibiotic compounds widely used in the dairy industry. Their presence in diary milk poses a risk to public health and may also contribute to the spread of antibiotic resistance in bacteria. Sulfonamide residues in dairy milk were quantified by tandem mass spectrometry (MS/MS) using a novel ionization source based on laser diode thermal desorption-negative mode atmospheric pressure chemical ionization (LDTD-APCI(-)). Seven sulfonamides spiked in milk were extracted with acetonitrile, which yielded high recoveries (77.5-101.5%). Calibration curves in the matrix showed good linearity (0.9977 g R2 g 0.9658)over the dynamic range (1.6-500 μgL −1), and limits of quantitation were between 2 and 14 μgL -1, lower than or of the same magnitude as maximum residue criteria set by several regulatory agencies (10-100 ng L −1). In addition, the run time using the LDTD-MS/MS system was 30 s per sample, as compared to actual methods running from 7 to 84 min for the same sulfonamide residue compounds, which gave the method the high screening throughput capacity necessary for monitoring milk production.
2007-2009
[…] surface water. J Chromatogr, A 1216:8518-8527.
We describe the development and validation of an on-line solid-phase extraction of large-volume injections coupled to liquid chromatography-tandem mass spectrometry method for the simultaneous quantitation and confirmation of 14 selected trace organic contaminants in drinking and surface water. Selected compounds were: anti-infectives (clarithromycin, sulfamethoxazole and trimethoprim), an anticonvulsant (carbamazepine) and its transformation product 10,11-dihydrocarbamazepine, an anti- hypertensive (enalapril), antineoplastics (cyclophosphamide and methotrexate), herbicides (atrazine, cyanazine, and simazine) and two of their transformation products (deethylatrazine and deisopropy- latrazine) and an antiseptic (triclocarban). The breakthrough volume determinations showed that out of all the investigated sorbents, the Strata-X on-line solid-phase extraction column showed the best performance. The method used a load volume of 10.0 mL and was validated using the corresponding matrices, yielding for most compounds, R2 > 0.99. Extraction recoveries ranged from 60 to 109%. The intra-and inter-day precision were < 14 and < 16%, respectively. The method detection limits ranged from 0.6 to 6 ng L−1. Matrix effects were in general low. The performance of the on-line method was demon- strated with the analysis of real water samples. The application of alternative techniques of confirmation was also explored using accurate mass measurements on a time-of-flight mass spectrometer and the data-dependent reverse energy ramp scan on a triple quadrupole.
We developed an on-line preconcentration liquid chromatography-tandem mass spectrom- etry method for the determination of the anti-infectives sulfamethoxazole, trimethoprim, ciprofloxacin, levofloxacin, clarithromycin and azithromycin in wastewaters using a turbulent flow chromatography load column. Recoveries for the target analytes were between 86 and 141%. Limits of quantification ranged from 45 to 122 ng L−1 and limits of confirmation from 37 to 142 ng L−1. This study shows that turbulent flow chromatography load columns are an interesting alternative for the on-line preconcentration of wastewater samples because they can be loaded at higher flow rates and are less affected by fouling, thus decreasing analysis time and enhancing method robustness necessary for the analysis of environmental trace pollutants.
Objective: Anti-infectives are constantly discharged at trace levels in natural waters near urban centers and agricultural areas. They represent a cause for concern because of their potential contribution to the spread of anti-infective resistance in bacteria and other effects on aquatic biota. We compiled data on the occurrence of anti-infectives published in the last 24 years in environmental water matrices. The collected information was then compared with the available ecotoxicologic values to evaluate potential environmental concerns. Data sources: We used Web of Science and Google Scholar to search for articles published in peer-reviewed journals written in the English language since 1984. Data extraction: Information on compound concentrations in wastewaters and natural and drinking waters, the source of contamination, country of provenance of the samples, year of publication, limits of quantification, and method of analysis was extracted. Data synthesis: From the 126 different substances analyzed in environmental waters, 68 different parent compounds and 10 degradation products or metabolites have been quantified to date. Environmental concentrations vary from about 10–1 to 109 ng/L, depending on the compound, the matrix, and the source of contamination. Conclusions: Detrimental effects of anti-infectives on aquatic microbiota are possible with the constant exposure of sensitive species. Indirect impact on human health cannot be ruled out when considering the potential contribution of high anti-infective concentrations to the spreading of anti-infective resistance in bacteria.
[…] tandem mass spectrometry. J Environ Monit 11:830-838.
We developed a rapid method for the monitoring of five selected pharmaceuticals in the influent and effluent of municipal wastewater treatment plants (WWTP) as well as in the effluent-receiving waters. To that end, we optimized and validated an analytical method based on on-line solid-phase extraction (on-line SPE) coupled with reversed-phase liquid chromatography-switching polarity electrospray ionization-tandem mass spectrometry (LC-ESI(±)-MS/MS). The target analytes have a variable hydrophobic character and belong to various therapeutic classes including the lipid regulator bezafibrate, the chemotherapy drugs methotrexate and cyclophosphamide, the lipase inhibitor orlistat and the angiotensin converting enzyme (ACE) inhibitor used in the treatment of hypertension, enalapril. The method combines positive and negative voltage switching modes, therefore all analytes can be determined using a single injection and without any reduction in sensitivity. In order to detect traces of these compounds, a preconcentration step before detection is performed by loading 1.00 mL of sample in an on-line SPE cartridge and eluting from the cartridge using a reversed-phase liquid chromatography gradient. Analysis of wastewater and surface water samples was greatly affected by co-eluting matrix compounds, to compensate for matrix effects quantitation was therefore performed using standard additions. Method intra-day precision was less than 6.5% and limits of detection in fortified matrix effluent samples ranged from 9 to 20 ng L−1. Four of the target pharmaceuticals were detected in the WWTP effluents, enalapril and bezafibrate being the most abundant compounds with concentrations of 35 and 239 ng L−1, respectively. Concentrations of these same compounds in surface water samples from sites downstream in the St. Lawrence River were 8 and 63 ng L−1, respectively, which was mainly due to dilution.
We developed and validated a novel on-line preconcentration liquid chromatography– tandem mass spectrometry method for the determination of anti-infectives inwastewaters. The presented method preconcentrates 1mL of sample in a load column using a switchingvalve technique. The method was optimized with respect to sample load flow rate, volume of the load column wash and organic solvent content of the load column wash. The sample is cleaned using a 30% organic solvent washing step and then gradually eluted to an analytical column for separation. To compensate for matrix effects, quantitation was performed using standard additions. Confirmation of the presence of the detected compounds was done using a second selective reaction monitoring transition. Method intra-day precision was less than 9% and inter-day precision %R.S.D. varied between 2.5 and 23%. Limits of detection for the selected anti-infective compounds ranged from 13 to 61 ng L−1. All the target anti-infectives were found in the city of Montr´ eal WWTP effluent in concentrations ranging from 71 to 289 ng L−1. This automated method eases the rapid quantitation of those trace contaminants using small sample volumes.
A rugged and specific method based on tandem solid-phase extraction and liquid chromatography–tandem mass spectrometry for the determination of anti-infectives in raw sewage and wastewater plant effluents was developed. Analyte recoveries from spiked effluents ranged from 68 to 104%. Two specific selected reaction monitoring transitions and their peak area ratios were used to avoid false positives and confirm the presence of the targeted substances. Detection limits allowed low nanogram per litre detection (0.3–22 ng L−1). The method was successfully applied to real samples from the Montre´ al wastewater treatment plant. All the studied antiinfectives were found in the wastewater samples in concentrations ranging from 39 to 276 ng L−1 Mean flows of anti-infectives were estimated from effluent concentrations and it was found that large amounts (4118 g day−1 up to 830 g day−1 are discharged in the receiving waters of the St Lawrence River.