Sung Vo Duy

Analysis of zwitterionic, cationic, and anionic poly- and perfluoroalkyl surfactants in sediments by liquid chromatography polarity-switching electrospray ionization coupled to high resolution mass spectrometry

A new analytical method is proposed for the determination of a wide span of fluoroalkylated surfactants (PFASs) of various chain lengths and polarities in sediments, including newly-identified compounds such as zwitterionic and cationic PFASs. Extraction conditions were optimized so as to maintain a common preparation procedure for all analytes (recovery range: 60-110%). Instrumental analysis was performed with ultra-high performance liquid chromatography coupled to Orbitrap mass spectrometry through polarity-switching electrospray ionization. Calibration curves with excellent coefficients of determination (R(2)>0.994) were generally obtained over 0.002-10ngg(-1) dry weight (dw) and limits of detection were in the range 0.0006-0.46 ng g(-1) dw. Intra-day precision remained<9% and inter-day precision<23%. While perfluorooctane sulfonate (PFOS) generally prevailed over other perfluoroalkyl acids (PFAAs) in sediments from mainland France, fluorotelomer sulfonamide amines and fluorotelomer sulfonamide betaines were also ubiquitous in these samples, especially in the vicinity of airports wherein firefighting training activities may occur on a regular basis.

Generation of Perfluoroalkyl Acids from Aerobic Biotransformation of Quaternary Ammonium Polyfluoroalkyl Surfactants

The aerobic biotransformation over 180 days of two cationic quaternary ammonium compounds (QACs) with perfluoroalkyl chains was determined in soil microcosms, and biotransformation pathways were proposed. This is the first time that polyfluoroalkyl cationic surfactants used in aqueous film-forming foam (AFFF) formulations were studied for their environmental fate. The biotransformation of perfluorooctaneamido quaternary ammonium salt (PFOAAmS) was characterized by a DT50 value (time necessary to consume half of the initial mass) of 142 days and significant generation of perfluoroalkyl carboxylic acid (PFOA) at a yield of 30 mol % by day 180. The biotransformation of perfluorooctane sulfonamide quaternary ammonium salt (PFOSAmS) was very slow with unobservable change of the spiked mass; yet the generation of perfluorooctanesulfonate (PFOS) at a yield of 0.3 mol % confirmed the biotransformation of PFOSAmS. Three novel biotransformation intermediates were identified for PFOAAmS and three products including perfluorooctane sulfonamide (FOSA) for PFOSAmS through high-resolution mass spectrometry (MS) analysis and t-MS(2) fragmentation. The significantly slower PFOSAmS biotransformation is hypothesized to be due to its stronger sorption to soil owing to a longer perfluoroalkyl chain and a bulkier sulfonyl group, when compared to PFOAAmS. This study has demonstrated that despite overall high stability of QACs and their biocide nature, the ones with perfluoroalkyl chains can be substantially biotransformed into perfluoroalkyl acids in aerobic soil.

Environmental Occurrence of Perfluoroalkyl Acids and Novel Fluorotelomer Surfactants in the Freshwater Fish Catostomus commersonii and Sediments Following Firefighting Foam Deployment at the Lac-Mégantic Railway Accident

On July 6th 2013, an unmanned train laden with almost 8 million liters of crude oil careened off the rails downtown Lac-Mégantic (Québec, Canada). In the aftermath of the derailment accident, the emergency response entailed the deployment of 33 000 L of aqueous film forming foam (AFFF) concentrate that contained proprietary fluorosurfactants. The present study examines the environmental occurrence of perfluoroalkyl acids (PFAAs) and newly identified per and polyfluoroalkyl substances (PFASs) in the benthic fish white sucker (Catostomus commersonii) and sediments from Lake Mégantic and Chaudière River. In sediments, PFAAs displayed relatively low concentrations (∑PFAAs = 0.06-0.5 ng g-1 dw) while the sum of fluorotelomer-based PFASs was in the range < LOD-6.2 ng g-1 dw. Notably, fluorotelomer sulfonamide betaines (8:2-FTAB and 10:2-FTAB), fluorotelomer betaines (9:3-FTB, 11:3-FTB and 9:1:2 FTB) and 6:2 fluorotelomer sulfonate (6:2-FTSA) were ubiquitously identified in the sediment samples surveyed. Levels of PFAAs remained moderate in fish muscle (e.g. , PFOS 0.28-2.1 ng g-1 wet-weight), with little or no differences when comparing 2013 or 2014 fish samples with 2011 archived samples. In contrast, n:2-FTSAs emerged in the immediate weeks or months that followed the accident, as did several betaine-based PFASs (8:2-FTAB, 10:2-FTAB, 9:3-FTB, 11:3-FTB, 7:1:2 FTB and 9:1:2 FTB), observed for the first time in situ. Fluorotelomer thioether amido sulfonate (10:2-FTSAS) and fluorotelomer sulfoxide amido sulfonate (10:2-FTSAS-sulfoxide) were also occasionally reported after the AFFF spill. With time, levels of betaine-based PFASs gradually decreased in fish, possibly indicating attenuation by biodegradation of the fluorine-free moiety, supported by the observation of likely metabolites such as n:3-fluorotelomer carboxylates and n:2-fluorotelomer sulfonamides.

Quantitative analysis of poly- and perfluoroalkyl compounds in water matrices using high resolution mass spectrometry: Optimization for a laser diode thermal desorption method

An alternative analysis technique for the quantitation of 15 poly- and perfluoroalkyl substances (PFASs) in water matrices is reported. Analysis time between each sample was reduced to less than 20s, all target molecules being analyzed in a single run with the use of laser diode thermal desorption atmospheric pressure chemical ionization (LDTD/APCI) coupled with high resolution accurate mass (HRMS) orbitrap mass spectrometry. LDTD optimal settings were investigated using either one-factor-at-a-time or experimental design methodologies, while orbitrap parameters were optimized simultaneously by means of a Box-Behnken design. Following selection of an adequate sample concentration and purification procedure based on solid-phase extraction and graphite clean-up, the method was validated in an influent wastewater matrix. Environmentally significant limits of detection were reported (0.3-4ngL(-1) in wastewater and 0.03-0.2ngL(-1) in surface water) and out of the 15 target analytes, 11 showed excellent accuracies (±20% of the target values) and recovery rates (75-125%). The method was successfully applied to a selection of environmental samples, including wastewater samples in 7 locations across Canada, as well as surface and tap water samples from the Montreal region, providing insights into the degree of PFAS contamination in this area.

On-line solid-phase extraction coupled to liquid chromatography tandem mass spectrometry for the analysis of cyanotoxins in algal blooms.

An analytical method based on on-line SPE-LC-HESI-MS/MS has been developed for the detection and quantification of eight selected cyanotoxins in algal bloom waters that include mycrocystins, anatoxin-a and cylindrospermopsin. The injection volume was 2 mL according to the expected concentration of cyanotoxins in matrix. The method provides an analysis time of 7 min per sample, acceptable recovery values (91-101%), good precision (RSD < 13%) and method limits of detection at the sub-microgram per liter levels (0.01-0.02 μg L(-1)). A detailed discussion on optimization parameters that have an impact on the overall performance of the method are presented. In particular, method optimization permitted the chromatographic separation of anatoxin-a and phenylalanine, an isobaric interference with a similar chromatographic characteristics. All optimization and validation experiments for the on-line SPE method and chromatographic separation were performed in environmentally relevant algal bloom water matrices. The applicability of the method was tested on several algal bloom water samples from monitored lakes across the province of Québec (Québec, Canada) known to produce cyanotoxins. All of the targeted cyanotoxins were detected with the exception of cylindrospermopsin. In addition, it was found that total microcystin concentrations in several surface water samples exceeded the proposed guidelines established by the province of Québec in Canada of 1.5 μg L(-1) as well as the World Health Organization of 1 μg L(-1) for both free and cell-bound microcystin-LR equivalent.

Novel Fluoroalkylated Surfactants in Soils Following Firefighting Foam Deployment During the Lac-Mégantic Railway Accident

The derailment of an unmanned train carrying crude oil and subsequent fire in the town of Lac-Mégantic, Quebec, led to the use of 33 000 L of aqueous film forming foam (AFFF) concentrate. While it is known that per- and polyfluoroalkyl substances (PFASs) contained in AFFFs pose a potential environmental and health risk, critical knowledge gaps remain as regards to their environmental fate after release. The accident in Lac-Mégantic provided valuable information regarding the identity and concentration of PFASs present in the soil after the AFFF deployment, as well as their possible transformation over time. The current study analyzed four sets of samples from Lac-Mégantic: soil collected days after the accident from a heavily impacted area, soil sampled two years later from the treatment biopiles, soil collected two years after the accident from downtown Lac-Mégantic, and nonimpacted soil from a nearby area. A total of 33 PFASs were quantified in the soils. The highest observed concentrations correspond to those of 6:2 fluorotelomer sulfonamidoalkyl betaine, 6:2 and 8:2 fluorotelomer sulfonates, and short chain perfluorocarboxylic acids. The soils collected in Lac-Mégantic two years after the accident show a total PFAS concentration that is ∼50 times lower than soils collected in 2013, while the proportion of perfluoroalkyl acids in those samples shows an increase. Qualitative analysis revealed the presence in soil of 55 additional PFASs that had been previously identified in AFFF formulations. The present study highlights the need to perform detailed analysis of AFFF impacted sites, instead of focusing solely on perfluoroalkyl acids.

Adsorption characteristics of multiple microcystins and cylindrospermopsin on sediment: Implications for toxin monitoring and drinking water treatment.

Adsorption of mixtures of cyanotoxins onto sediment as a dominant mechanism in the elimination of cyanotoxins from the aqueous phase has not been extensively investigated. The aim of this study was to investigate adsorption and desorption behavior of six microcystins including microcystin (MC)-LR, RR, YR, LY, LW and LF and cylindrospermopsin (CYN) on natural sediment. Freundlich and Langmuir isotherms could be fitted for MC-LR, RR, YR and CYN. Sorption kinetics showed immediate rapid adsorption for all cyanotoxins: CYN, MCLW and MCLF were adsorbed 72.6%, 56.7% and 55.3% respectively within 2 h. Results of desorption experiments demonstrated that less than 9% of cyanotoxins desorbed from sediment within 96 h. Adsorption of cyanotoxins onto three fractionated sediments particles, clay-silt (<75 μm), find sand (75-315 μm) and coarse sand (315-2000 μm) demonstrated that adsorption capacity of coarse sand fraction for all the tested cyanotoxins was less than 4% of the clay-silt fraction. Results of this study revealed that there is a potential for cyanotoxins to accumulate in the sediments of lakes, as well as in drinking water treatment plants. Monitoring programs must consider cyanotoxins in the particulate phase to avoid largely underestimating toxin concentrations following their release from blooms.

Fluoxetine and its active metabolite norfluoxetine disrupt estrogen synthesis in a co-culture model of the feto-placental unit

The effects of fluoxetine, one of the most prescribed selective serotonin-reuptake inhibitors (SSRIs) during pregnancy, and its active metabolite norfluoxetine were studied on placental aromatase (CYP19) and feto-placental steroidogenesis. Fluoxetine did not alter estrogen secretion in co-culture of fetal-like adrenocortical (H295R) and trophoblast-like (BeWo) cells used as a model of the feto-placental unit, although it induced CYP19 activity, apparently mediated by the serotonin (5-HT)2A receptor/PKC signaling pathway. Norfluoxetine decreased estrogen secretion in the feto-placental co-culture and competitively inhibited catalytic CYP19 activity in BeWo cells. Decreased serotonin transporter (SERT) activity in the co-culture was comparable to 17β-estradiol treatment of BeWo cells. This work shows that the complex interaction of fluoxetine and norfluoxetine with placental estrogen production, involves 5-HT-dependent and -independent mechanisms. Considering the crucial role of estrogens during pregnancy, our results raise concern about the impact of SSRI treatment on placental function and fetal health.

Biodegradation of multiple microcystins and cylindrospermopsin in clarifier sludge and a drinking water source: Effects of particulate attached bacteria and phycocyanin.

The effects of particulate attached bacteria (PAB) and phycocyanin on the simultaneous biodegradation of a mixture of microcystin-LR, YR, LY, LW, LF and cylindrospermopsin (CYN) was assessed in clarifier sludge of a drinking water treatment plant (DWTP) and in a drinking water source. The biomass from lake water and clarifier sludge was able to degrade all microcystins (MCs) at initial concentrations of 10µgL(-1) with pseudo-first order reaction half-lives ranging from 2.3 to 8.8 days. CYN was degraded only in the sludge with a biodegradation rate of 1.0×10(-1)d(-1) and a half-life of 6.0 days. This is the first study reporting multiple MCs and CYN biodegradation in the coagulation-flocculation sludge of a DWTP. The removal of PAB from the lake water and the sludge prolonged the lag time substantially, such that no biodegradation of MCLY, LW and LF was observed within 24 days. Biodegradation rates were shown to increase in the presence of C-phycocyanin as a supplementary carbon source for indigenous bacteria, a cyanobacterial product that accompanies cyanotoxins during cyanobacteria blooms. MCs in mixtures degraded more slowly (or not at all) than if they were degraded individually, an important outcome as MCs in the environment are often present in mixtures. The results from this study showed that the majority of the bacterial biomass responsible for the biodegradation of cyanotoxins is associated with particles or biological flocs and there is a potential for extreme accumulation of cyanotoxins within the DWTP during a transient bloom.

Analysis of nine N-nitrosamines using liquid chromatography-accurate mass high resolution-mass spectrometry on a Q-Exactive instrument

A selective and robust methodology for the analysis of nine N-nitrosamines (NAs), N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMor), N-nitrosomethylethylamine (NMEA), N-nitrosopyrrolidine (NPyr), N-nitrosodiethylamine (NDEA), N-nitrosopiperidine (NPip), N-nitroso-n-dipropylamine (NDPA), N-nitrosodi-n-butylamine (NDBA) and N-nitrosodi-n-phenylamine (NDPhA), was developed and validated. This method is based on ultra-high-performance liquid chromatography (UHPLC) coupled to mass spectrometry using heated electrospray ionization (HESI) in positive ionization mode with a Q-Exactive mass spectrometer. After the selection of a suitable column for NA separation, the mobile phase and the injection volume as chromatography parameters were optimized. Mass spectrometry operating parameters, including sheath gas, auxiliary gas, spray voltage, S-Lens RF Level, resolution, automatic gain control (AGC) target and maximum injection time, were also optimized in order to maximize the instrument analytical signal response. The method was optimized and validated in HPLC grade water, drinking water and wastewater matrices with satisfactory results. For accurate quantification, NDMA-d6 and NDPA-d14 were used as internal standards. The extraction recoveries in real matrices ranged from 68–83% for eight of the nine target nitrosamines, except for NDPhA with values of 22–31%. The detection limits ranged from 0.4 to 12 ng L−1. Analytical results revealed a trace concentration of NDPhA (1.2 ng L−1) in one of the analyzed water matrices. This work demonstrates that nitrosamines can be analyzed using LC-MS, on a Q-Exactive instrument, offering a faster alternative to the traditional GC-MS methods. The use of high resolution accurate mass spectrometry helps to obtain good selectivity for the detection of both GC-detectable and GC-undetectable compounds.