[show abstract][hide abstract] ABSTRACT: The consequences of global change on rivers include altered flow regime, and entrance of compounds that may be toxic to biota. When water is scarce, a reduced dilution capacity may amplify the effects of chemical pollution. Therefore, studying the response of natural communities to compromised water flow and to toxicants is critical for assessing how global change may affect river ecosystems. This work aims to investigate how an episode of drought might influence the response of river biofilms to pulses of triclosan (TCS). The objectives were to assess the separate and combined effects of simulated drought (achieved through drastic flow alteration) and of TCS exposure on biofilms growing in artificial channels. Thus, three-week-old biofilms were studied under four conditions: Control (normal water flow); Simulated Drought (1 week reduced flow + 2 days interrupted flow); TCS only (normal water flow plus a 48-h pulse of TCS); and Simulated Drought + TCS. All channels were then left for 2 weeks under steady flow conditions, and their responses and recovery were studied. Several descriptors of biofilms were analyzed before and after each step. Flow reduction and subsequent interruption were found to provoke an increase in extracellular phosphatase activity, bacterial mortality and green algae biomass. The TCS pulses severely affected biofilms: they drastically reduced photosynthetic efficiency, the viability of bacteria and diatoms, and phosphate uptake. Latent consequences evidenced significant combined effects caused by the two stressors. The biofilms exposed only to TCS recovered far better than those subjected
to both altered flow and subsequent TCS exposure: the latter suffered more persistent consequences, indicating that simulated drought amplified the toxicity of this compound. This finding has implications for river ecosystems, as it suggests that the toxicity of pollutants to biofilms may be exacerbated following a drought.
[show abstract][hide abstract] ABSTRACT: Triclosan is a commonly used bactericide that survives several degradation steps in WWTP (wastewater treatment plants) and potentially reaches fluvial ecosystems. In Mediterranean areas, where water scarcity results in low dilution capacity, the potential environmental risk of triclosan is high. A set of experimental channels was used to examine the short-term effects of triclosan (from 0.05 to 500μgL⁻¹) on biofilm algae and bacteria. Environmentally relevant concentrations of triclosan caused an increase of bacterial mortality with a no effect concentration (NEC) of 0.21μgL⁻¹. Dead bacteria accounted for up to 85% of the total bacterial population at the highest concentration tested. The toxicity of triclosan was higher for bacteria than algae. Photosynthetic efficiency was inhibited with increasing triclosan concentrations (NEC=0.42μgL⁻¹), and non-photochemical quenching mechanisms decreased. Diatom cell viability was also affected with increasing concentrations of triclosan. Algal toxicity may be a result of indirect effects on the biofilm toxicity, but the clear and progressive reduction observed in all the algal-related endpoints suggest the existence of direct effects of the bactericide. The toxicity detected on the co-occurring non-target components of the biofilm community, the capacity of triclosan to survive through WWTP processes and the low dilution capacity that characterizes Mediterranean systems extend the relevance of triclosan toxicity beyond bacteria in aquatic habitats.
[show abstract][hide abstract] ABSTRACT: This study deals with a simple strategy to pinpoint potential unknown compounds in full scan mass spectrometry (MS) experiments. Forty samples of apples and pears intended for human consumption were analyzed by ultra-high performance liquid chromatography quadrupole-time-of-flight (UPLC-QqTOF-MS), after extraction of the possible contaminants by rinsing the peel of the fruit with ethyl acetate. The peaks were visually recognized in the total ion chromatogram (TIC). Two major types of postharvest treatments were detected in this set of samples: imazalil (IMZ)/ethoxyquin (EQ) and thiabendazole (TBZ)/diphenylamine (DPA). The present work also describes the metabolites formed by degradation of EQ (to our knowledge not previously reported) and DPA (there was mass spectral evidence of some of them but full identification was not pursued). Hydroxy-DPA, n-phenyl-4-quinoneimine, methoxy-DPA, demethyl-EQ, demethyldehydro-EQ, EQ-dimer, methyl-EQ, EQ-N-oxyl and 2',2,4,-trimethyl-6-quinolone were unequivocally identified and confirmed. Some relationships between the applied postharvest treatment and the metabolites formed were established. Remarkably, they may constitute a useful fingerprint in further investigations of postharvest treatments. Among other significant results, the study also reveals for the first time the presence of some EQ metabolites in fruits, which are different from those previously reported in animal tissues. There is not information on the occurrence of EQ metabolites in fruits and the DPA ones have not been studied extensively in pears and apples. The levels of the metabolites found exceeded several times those of the parent compounds.
[show abstract][hide abstract] ABSTRACT: Due to their unique properties, carbon-based nanomaterials (CNMs) have attracted considerable interest in many fields of research, including materials sciences, microelectronics and biomedicine. The potential, the growing use and the mass production of fullerenes and carbon nanotubes have stimulated research on their potential impact on the environment and human health. To gather proper information about hazards of CNMs, it is important to have reliable analytical data on them, to find out how they behave in the environment and to evaluate ecotoxicological information about them.This review presents the latest research carried out to assess the risks of engineered CNMs in the aquatic environment, including analytical methods and ecotoxicity assessment. We pay special attention to the surface properties of CNMs, which are vitally important for their aggregation behavior, their mobility in aquatic systems, their interactions with aquatic organisms, and their possible entry into the food chain. We also consider interactions with natural organic matter and other interactions that can alter aggregation behavior in water.
[show abstract][hide abstract] ABSTRACT: Endocrine disrupters (EDs) continue to be the focus of extensive research. Their effects and mode of action as well as their
occurrence and fate in the aquatic environment are still largely unknown and need investigation. Wastewater treatment plant
effluents are for most of them the main source of contamination in water bodies. A large number of EDs are relatively polar
compounds that pass easily wastewater treatments and reach the aquatic environment, where they can exert undesirable effects
on both wildlife and humans. Their removal during waste-water treatment, very often inefficient, is usually estimated from
the comparison of the concentrations detected at the influent and the effluent and the technique of choice for their analysis
is in many cases liquid chromatography—(tandem)mass spectrometry (LC—(tandem)MS).
Herein we review the analytical methods, including sample preparation and analysis, based on LC—(tandem)MS described in the
literature for the determination of different classes of EDs (pesticides, phthalates, bisphenol A, alkylphenolic compounds,
perfluorinated compounds, pharmaceuticals, and estrogens) in wastewater and their occurrence in this kind of matrix.
[show abstract][hide abstract] ABSTRACT: A method has been developed for identification and quantification of the acaricide amitraz and its transformation products, 2,4-dimethylaniline (DMA), 2,4-dimethylformamidine (DMF) and N-2,4-dimethylphenyl-N-methylformamidine (DMPF) in pears. The analytes were extracted using ethyl acetate and anhydrous sodium sulphate. Analysis was performed by liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS) in the positive ion mode using a triple quadrupole (QqQ) instrument. Two precursor-product ion transitions were monitored for each compound in the selected reaction monitoring (SRM) mode. The method was validated with pears taken from the orchard before the amitraz treatment and spiked at the limit of quantification (LOQ), 10 times the LOQ and the maximum residue limit (MRL). Recoveries were between 70 and 106% and relative standard deviations were below 19% (n=5 at each spiked level). Excellent sensitivity resulted in limits of detection (LODs) for all the compounds below 10 microg kg(-1). Quantification was carried out using matrix-matched standards calibration, response was a linear function of the concentration from the LOQs to, at least, three orders of magnitude. Recoveries and standard deviations were comparable to those obtained after hydrolysis of amitraz and its metabolites to DMA. Occurrence of amitraz and its metabolites in field-treated pears showed that, seven days after the treatment, DMPF and DMF are the main degradation products. This work reports for the first time the use of a conventional pesticide multiresidue method and LC-ESI-MS/MS for determining amitraz and its metabolites in pears.
Journal of chromatography. A 03/2009; 1216(15):3138-46. · 4.19 Impact Factor
[show abstract][hide abstract] ABSTRACT: Liquid chromatography under high pressure in combination with quadrupole time-of-flight mass spectrometry (QqTOF-MS and MS/MS) has been used to detect amitraz degradation products in pears, to characterize their structures, and to evaluate their occurrences in samples of different origins. Using the proposed approach, the parent pesticide and four degradation products were identified. To this end, pear samples were extracted with ethyl acetate and anhydrous sodium sulphate. Amitraz was found to be rapidly decomposed into four related compounds, of which N-(2,4-dimethylphenyl)formamidine (DMPF) was the most abundant and persistent. N,N'-bisdimethylphenylformamidine (BDMPF), 2,4-dimethylformamidine (DMF) and 2,4-dimethyl aniline (DMA) were also main metabolites of amitraz. To our knowledge this is the first report that confirms the presence of BDMPF in pears. The method was validated using MS and MS/MS for those standard available (analytical or not). In MS, recoveries ranged from 83 to 101% with relative standard deviation (RSD) from 9 to 19% at the limit of quantification (LOQ) (between 5 and 20 microg kg(-1)). Using MS/MS, recoveries, linearity and precision were similar but LOQs were higher because the intense fragmentation of the protonated molecules in the product mass spectrum. BDMPF, as an approximation, was quantified based on the DMF metabolite. The results demonstrated that high-pressure LC-QqTOF-MS and MS/MS techniques enhance further the capabilities of LC-MS in the identification of polar species in complex food samples.
Journal of Chromatography 08/2008; 1203(1):36-46. · 4.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: Ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QqTOF-MS) is an emerging technique offering more rapid and efficient separation, as well as the possibility to obtain accurate mass measurement and tandem mass spectrometry (MS/MS). This paper deals with the use of UPLC-QqTOF-MS to identify the pesticide residues present in complex pear extracts. Carbendazim, imazalil, and ethoxyquin were successfully identified because of the accurate mass determination of their protonated molecule and their major fragments in the product ion mass spectra. A few plastic and latex additives were also found, most of them probably coming from the packaging transfer to the fruits. The potential of the UPLC-QqTOF-MS and UPLC-QqTOF-MS/MS techniques as a quantification tool is also discussed taking imazalil as example. For quantification, calibration curves were linear over a dynamic range of 2 orders of magnitude, whereas higher calibration ranges are better adjusted to polynomial curves of second and third order. Quantification using different mass windows was also assessed. Accurate quantification required mass windows as wide as 20 mDa, narrower mass windows of 5 mDa provided erroneous quantification, probably because the low ion abundance. The mean recoveries and percentage relative standard deviation (RSD) of 35 determinations for imazalil were 76% (13% RSD) by MS and 77% (14% RSD) by MS/MS. The theoretical limit of detection was 0.4 microg kg(-1), with a validated limit of quantification of 2 microg kg(-1). The quantitative data obtained using UPLC-QqTOF-MS were compared with those obtained using conventional liquid chromatography (LC)-MS/MS with a triple quadrupole (QqQ). It was concluded that UPLC-QqTOF-MS might become a powerful analytical tool for both, unknown's identification and quantification of target pesticides.
Journal of Chromatography 01/2008; 1176(1-2):123-34. · 4.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: There has been a great effort to study the fate, the occurrence and the ecotoxicology of emerging pollutants in the aquatic environment. Recently, several articles have focused on degradation products of emerging pollutants and the study of their toxicological effects.We review the fate and the ecotoxicology of emerging pollutants, especially focusing on their metabolites and transformation products (TPs) in the aquatic environment, including pharmaceuticals, hormones, perfluorinated compounds, by-products of drinking-water disinfection, sunscreens or UV filters, benzotriazoles and naphthalenic acids.We describe analytical methodologies for the quantitative analysis of emerging pollutants, their metabolites, and their TPs in sewage and surface waters, and we give the results of monitoring surveys obtained from the application of these analytical methodologies.
[show abstract][hide abstract] ABSTRACT: In the present work a combined analytical method involving toxicity and liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) was developed for the determination of pharmaceutical compounds in water samples. The drugs investigated were the analgesics: ibuprofen, ketoprofen, naproxen, and diclofenac, the decomposition product of the acetyl salicylic acid: salicylic acid and one lipid lowering agent, gemfibrozil. The selected compounds are acidic substances, very polar and all of them are analgesic compounds that can be purchased without medical prescription. The developed protocol consisted, first of all, on the use Microtox and ToxAlert 100 toxicity tests with Vibriofischeri for the different pharmaceutical drugs. The 50% effective concentration (EC50) values and the toxicity units (TU) were determined for every compound using both systems. Sample enrichment of water samples was achieved by solid-phase extraction procedure (SPE), using the Merck LiChrolut EN cartridges followed by LC-ESI-MS. Average recoveries loading 11 of samples with pH=2 varied from 69 to 91% and the detection limits in the range of 15-56 ng/l. The developed method was applied to real samples from wastewater and surface-river waters of Catalonia (north-east of Spain). One batch of samples was analyzed in parallel also by High Resolution Gas Chromatography coupled with Mass Spectrometry (HRGC-MS) and the results have been compared with the LC-ESI-MS method developed in this work.
Journal of Chromatography 01/2002; 938(1-2):187-97. · 4.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: The contribution of polycyclic aromatic hydrocarbons (PAH) present in sewage sludge samples to toxicity was investigated. Chemical analysis using gas chromatography–mass spectrometry (GC–MS) and the ToxAlert® 100 bioassay, based on the inhibition to Vibrio fischeri, were applied to sludge extracts after purification by column chromatography. The levels of the 16 US EPA PAH analyzed in the sewage sludge samples varied from 17 to . In all samples examined phenanthrene was the most prominent compound. The toxicity data obtained by ToxAlert® 100 can be explained by the levels and composition of the different PAH in sewage sludge samples. The present approach can contribute to evaluate the toxicity of sewage sludge.
[show abstract][hide abstract] ABSTRACT: The toxic response of commonly used non-ionic surfactants with different bioluminescence inhibition assays (ToxAlert®100 and Microtox®) were established. The 50% effective concentration (EC50) values were determined for every standard substance using each assay, together with toxicity units (TU). A sigmoidal curve was fitted and the (EC50) was calculated.Chemical analysis and bioassays were used in conjunction to provide a determination of aquatic toxicity in wastewaters. This methodology was applied to real samples of influent and effluent wastewater treatment works in Spain and Portugal and also for untreated textile wastewater effluents.The protocol used in this paper involved different steps. First, the aquatic toxicity evaluation for every effluent was carried out using ToxAlert®100. For every one, a sigmoidal curve was fitted, the (EC50) and the toxicity impact index (TII50) were calculated. Second, the identification and quantification of polar organic cytotoxic substances and their contribution to the total toxicity was obtained, using sequential solid-phase extraction (SSPE) followed by liquid chromatography-mass spectrometry (LC-MS).The use of toxicity results (in terms of bioluminescence inhibition) like a screening parameter, is proposed. This procedure excludes the chromatographic analysis if the sample has less than the 20% inhibition. Overall, this procedure presented here helps to reduce the large number of samples and sub-samples that need to be processed in wastewater monitoring.