Meritxell Gros - Profile on Academia.edu (original) (raw)

Papers by Meritxell Gros

Journal of Veterinary Pharmacology and Therapeutics, 2010

Multi-residue analysis of pharmaceuticals in wastewater by ultra-performance liquid chromatography–quadrupole–time-of-flight mass spectrometry

In this work, a new multi-residue method using ultra-performance liquid chromatography (UPLC) qua... more In this work, a new multi-residue method using ultra-performance liquid chromatography (UPLC) quadrupole-time-of-flight mass spectrometry (Q-TOF-MS) was developed for screening and confirmation of 29 pharmaceutical compounds belonging to different therapeutical classes: analgesics and antiinflammatories, lipid regulating agents cholesterol lowering statin agents, psychiatric drugs, anti ulcer agents, histamine H2 receptor antagonist, antibiotics and beta-blockers. UPLC uses columns packed with 1.7 microm particles and enables elution of sample components in much narrower, more concentrated bands, resulting in better chromatographic resolution and increased peak height. The typical peak width was 5-10s at base, permitting very good separation of all compounds in 10 min, which represented an approximate three-fold reduction in the analysis time in comparison to conventional high-performance liquid chromatography (HPLC). Unequivocal identification of target pharmaceutical compounds was based on accurate mass measurement of the molecular ions in the TOF mode and by performing collision induced dissociation (CID) in the Q-TOF mode in order to generate accurate mass measurement of the product ions. Using lock mass correction the accurate masses calculated for the product ions deviated from the theoretical masses by 0.2 to 1.3 mDa (root mean square (RMS) value=0.67) and 0.7-6.4 ppm (RMS=3.53), respectively. Quantitation was carried out working in the TOF mode using the narrow window extracted ion chromatograms (nwXICs) of each compound (extracted using a 20 mDa window) yielding relative standard deviation (RSD) from 0.5 to 5.3% (run-to-run) and from 2.1 to 9.1% (day-to-day) and instrumental detection limits (IDLs) from 1 to 200 pg. Analysis of wastewater treatment plant (WWTP) samples gave method detection limits (MDLs) ranging from 10 to 500 ng/L. The UPLC-Q-TOF method was successfully applied to analyze pharmaceutical residues in WWTP samples.

Sample preservation for the analysis of antibiotics in water

This paper describes a stability study performed for 56 antibiotics belonging to 9 different grou... more This paper describes a stability study performed for 56 antibiotics belonging to 9 different groups--macrolides, tetracyclines, fluoroquinolones, quinolones, penicillins, cephalosporines, lincosamides, sulfonamides and nitroimidazole antibiotics--in purified water samples fortified with the selected compounds at 10 ng/ml. For this purpose, three different sample preservation modes were tested with the aim of avoiding biotic and abiotic degradation: (i) storage at -20°C, (ii) storage at -20°C with 0.1% of EDTA and (iii) pre-concentration in a solid phase extraction cartridge (SPE), which was afterwards stored at -20°C. Concentrations of antibiotics in the samples preserved using the different protocols were monitored after 0, 1, 2 and 12 weeks. The results showed that, for the accurate determination of all compounds they should be analyzed right after sampling. However, if this is not possible, most of the antibiotics can be analyzed within the 1st week after sampling and preservation at -20°C (with or without EDTA) or in a SPE cartridges at -20°C. Nonetheless, some antibiotics found extensively in the environment, such as sulfamethoxazole, ciprofloxacin, ofloxacin, erythromycin, azithromycin and clarithromycin exhibited low stability after 1 week preservation and, therefore, they should be analyzed within this time.

Occurrence of antibiotics and antibiotic resistance genes in hospital and urban wastewaters and their impact on the receiving river

Water research, 2015

Antibiotic resistance has become a major health concern; thus, there is a growing interest in exp... more Antibiotic resistance has become a major health concern; thus, there is a growing interest in exploring the occurrence of antibiotic resistance genes (ARGs) in the environment as well as the factors that contribute to their emergence. Aquatic ecosystems provide an ideal setting for the acquisition and spread of ARGs due to the continuous pollution by antimicrobial compounds derived from anthropogenic activities. We investigated, therefore, the pollution level of a broad range of antibiotics and ARGs released from hospital and urban wastewaters, their removal through a wastewater treatment plant (WWTP) and their presence in the receiving river. Several antimicrobial compounds were detected in all water samples collected. Among antibiotic families, fluoroquinolones were detected at the highest concentration, especially in hospital effluent samples. Although good removal efficiency by treatment processes was observed for several antimicrobial compounds, most antibiotics were still pres...

Talanta, Jan 15, 2006

This paper describes development, optimization and validation of a method for the simultaneous de... more This paper describes development, optimization and validation of a method for the simultaneous determination of 29 multi-class pharmaceuticals using off line solid phase extraction (SPE) followed by liquid chromatography-triple quadrupole mass spectrometry (LC-MS-MS). Target compounds include analgesics and non-steroidal anti-inflammatories (NSAIDs), lipid regulators, psychiatric drugs, anti-histaminics, anti-ulcer agent, antibiotics and beta-blockers. Recoveries obtained were generally higher than 60% for both surface and wastewaters, with exception of several compounds that yielded lower, but still acceptable recoveries: ranitidine (50%), sotalol (50%), famotidine (50%) and mevastatin (34%). The overall variability of the method was below 15%, for all compounds and all tested matrices. Method detection limits (MDL) varied between 1 and 30ng/L and from 3 to 160ng/L for surface and wastewaters, respectively. The precision of the method, calculated as relative standard deviation (R.S...

Emerging Contaminants from Industrial and Municipal Waste, 2008

This book on "Emerging Contaminants from Industrial and Municipal Waste" is based on the scientif... more This book on "Emerging Contaminants from Industrial and Municipal Waste" is based on the scientific developments and results achieved within the European Union (EU)-funded project EMCO (reduction of environmental risks posed by emerging contaminants, through advanced treatment of municipal and industrial wastes). One of the key elements of the EMCO project was to provide support to the various Western Balkans countries involved in the project as regards the implementation of the Water Framework Directive (WFD) (2000/60/EC). A regional network, as proposed by the EMCO project, aiming to ensure the comparability (and reliability) of measurement data obtained by screening methodologies for water quality management, would support the EU Water Initiative, which aims to promote co-operation between countries in order to better manage their water resources.

Rapid analysis of multiclass antibiotic residues and some of their metabolites in hospital, urban wastewater and river water by ultra-high-performance liquid chromatography coupled to quadrupole-linear ion trap tandem mass spectrometry

Journal of Chromatography A, 2013

The present work describes the development of a fast and robust analytical method for the determi... more The present work describes the development of a fast and robust analytical method for the determination of 53 antibiotic residues, covering various chemical groups and some of their metabolites, in environmental matrices that are considered important sources of antibiotic pollution, namely hospital and urban wastewaters, as well as in river waters. The method is based on automated off-line solid phase extraction (SPE) followed by ultra-high-performance liquid chromatography coupled to quadrupole linear ion trap tandem mass spectrometry (UHPLC-QqLIT). For unequivocal identification and confirmation, and in order to fulfill EU guidelines, two selected reaction monitoring (SRM) transitions per compound are monitored (the most intense one is used for quantification and the second one for confirmation). Quantification of target antibiotics is performed by the internal standard approach, using one isotopically labeled compound for each chemical group, in order to correct matrix effects. The main advantages of the method are automation and speed-up of sample preparation, by the reduction of extraction volumes for all matrices, the fast separation of a wide spectrum of antibiotics by using ultra-high-performance liquid chromatography, its sensitivity (limits of detection in the low ng/L range) and selectivity (due to the use of tandem mass spectrometry) The inclusion of β-lactam antibiotics (penicillins and cephalosporins), which are compounds difficult to analyze in multi-residue methods due to their instability in water matrices, and some antibiotics metabolites are other important benefits of the method developed. As part of the validation procedure, the method developed was applied to the analysis of antibiotics residues in hospital, urban influent and effluent wastewaters as well as in river water samples.

Journal of Chromatography A, 2008

This paper describes the development of an analytical methodology to determine eight ␤-blockers i... more This paper describes the development of an analytical methodology to determine eight ␤-blockers in waste waters using molecularly imprinted polymers (MIPs) as extraction and pre-concentration material, followed by liquid chromatography-quadrupole-linear ion trap mass spectrometry (LC-QqLIT MS). The advantages offered by MIPs, in terms of selectivity and specificity, were compared with the most commonly polymeric materials used (the lipophilic-hydrophilic balanced Oasis ® HLB cartridges). Even though recoveries achieved with both sorbents were similar, ranging from 50 to 110% for sewage treatment plant (STP) effluent and 40-110 for STP influent, respectively, MIPs provided lower method detection limits than Oasis ® HLB, due to their specificity for target analytes and closely related analogues. Method detection limits (MDL) achieved using MIPs ranged from 0.2 to 6.4 ng/L for STP effluent and from 0.4 to 6.5 ng/L for STP influent. To highlight the advantages of MIPs against conventional polymeric cartridges, a detailed matrix effects study as well as cross reactivity tests were performed. For the latter purpose, the extraction efficiency of some pharmaceuticals and pesticides belonging to different therapeutic classes was assessed. LC-QqLIT MS, used for quantification and confirmation, proved to be a powerful analytical tool, as instrumental detection limits (IDL) achieved ranged from 0.2 to 2.7 pg injected (in multiple reaction monitoring mode (MRM)). In addition the inclusion of high sensitive MS/MS scans for each compound when working in Information Dependent Acquisition mode (IDA) provided extra confirmation for unequivocal identification of target compounds in complex environmental matrices.

Journal of Chromatography A, 2004

We describe in this paper simple and robust analytical protocols to determine the 16 polycyclic a... more We describe in this paper simple and robust analytical protocols to determine the 16 polycyclic aromatic hydrocarbons (PAHs) of the US Environmental Protection Agency priority list in water, sediment and mussels. For water samples, eight different solid-phase extraction (SPE) sorbents have been compared and among them, C 18 provided highest recoveries and limits of detection of 0.3-15 ng/L. For lyophilized sediments, Soxhlet and ultrasonic extraction were compared, and the last one permitted to recover all analytes with highest repetitivity and was validated by analysing a certified reference material. Finally, the analysis of mussels was undertaken using Soxhlet, ultrasonic and pressurized liquid extraction (PLE) and the performance of several clean-up steps are compared. Whereas for the former two, incomplete recovery or losses of some analytes were evidenced, PLE permitted a more efficient extraction and although alkaline digestion was necessary to remove coextracted compounds, the method gave acceptable recoveries and limits of detection of 0.5-7.7 g/kg dry mass, as for sediments. In all cases, analysis was performed by gas chromatography coupled to mass spectrometry and internal standard quantification was performed using five deuterated PAHs. Each method performance is discussed for the three matrices analysed and the paper reports advantages and disadvantages of each for their routine application in monitoring programs.

Occurrence and fate of emerging wastewater contaminants in Western Balkan Region

The Science of the total environment, Jan 25, 2008

This paper reports on a comprehensive reconnaissance of over seventy individual wastewater contam... more This paper reports on a comprehensive reconnaissance of over seventy individual wastewater contaminants in the region of Western Balkan (WB; Bosnia and Herzegovina, Croatia and Serbia), including some prominent classes of emerging contaminants such as pharmaceuticals and personal care products, surfactants and their degradation products, plasticizers, pesticides, insect repellents, and flame retardants. All determinations were carried out using a multiresidue analytical approach, based on the application of gas chromatographic and liquid chromatographic techniques coupled to mass spectrometric detection. The results confirmed a widespread occurrence of the emerging contaminants in municipal wastewaters of the region. The most prominent contaminant classes, determined in municipal wastewaters, were those derived from aromatic surfactants, including linear alkylbenzene sulphonates (LAS) and alkylphenol polyethoxylates (APEO), with the concentrations in raw wastewater reaching into the...

Environmental Toxicology and Chemistry, 2007

The occurrence of 28 pharmaceuticals of major human consumption in Spain, including analgesics an... more The occurrence of 28 pharmaceuticals of major human consumption in Spain, including analgesics and anti-inflammatories, lipid regulators, psychiatric drugs, antibiotics, antihistamines, and ␤-blockers, was assessed along the Ebro river basin, one of the biggest irrigated lands in that country. Target compounds were simultaneously analyzed by off-line solid-phase extraction, followed by liquid chromatography-tandem mass spectrometry. The loads of detected pharmaceuticals and their removal rates were studied in seven wastewater treatment plants (WWTPs) located in the main cities along the basin. Total loads ranged from 2 to 5 and from 0.5 to 1.5 g/d/1,000 inhabitants in influent and effluent wastewaters, respectively. High removal rates (60-90%) were achieved mainly for analgesics and anti-inflammatories. The other groups showed lower rates, ranging from 20 to 60%, and in most cases, the antiepileptic carbamazepine, macrolide antibiotics, and trimethoprim were not eliminated at all. Finally, the contribution of WWTP effluents to the presence of pharmaceuticals in receiving river waters was surveyed. In receiving surface water, the most ubiquitous compounds were the analgesics and anti-inflammatories ibuprofen, diclofenac, and naproxen; the lipid regulators bezafibrate and gemfibrozil; the antibiotics erythromycin, azithromycin, sulfamethoxazole, trimethoprim, and less frequently, ofloxacin; the antiepileptic carbamazepine; the antihistamine ranitidine; and the ␤-blockers atenolol and sotalol. Although levels found in WWTP effluents ranged from low g/L to high ng/L, pharmaceuticals in river waters occurred at levels at least one order of magnitude lower (low ng/L range) because of dilution effect. From the results obtained, it was proved that WWTP are hot spots of aquatic contamination concerning pharmaceuticals of human consumption.

Environment International, 2010

In a long term study, which covered 4 sampling periods over three years, a total number of 84 sam... more In a long term study, which covered 4 sampling periods over three years, a total number of 84 samples, specifically 28 influent, effluent, from seven WWTP located in the main cities along the Ebro river Basin (North East of Spain), as well as receiving river waters, were analyzed to assess the occurrence of 73 pharmaceuticals covering several medicinal classes. Results indicated that pharmaceuticals are widespread pollutants in the aquatic environmental. Linking the calculation of removal rates with half-lives, assuming that compound degradation followed pseudo-first order kinetics, suggested that conventional wastewater treatments applied at the seven WWTP were unable to completely remove most of the pharmaceuticals under study. The evaluation of compound degradability, in terms of half-lives, is an important task to discuss integrated solutions for mitigation of pollutants entry into the water cycle. High half-lives observed for the majority of pharmaceuticals in WWTP suggest that, in order to enhance compound degradation, higher hydraulic retention times should be required. The wide spectrum of substances detected in receiving river waters indicates that WWTP outlets are major contributors of pharmaceuticals in the aquatic environment. However, municipal wastewater treatment represents an obligatory and final treatment step prior to their release into the aquatic media, since load of pharmaceuticals in outlets were considerably reduced after treatment. Finally, hazard posed by pharmaceuticals in both surface and effluent wastewaters was assessed toward different aquatic organisms, (algae, daphnids and fish). The overall relative order of susceptibility was estimated to be algae > daphnia > fish. Results indicate that no significant risks could be associated to the presence of pharmaceuticals in those matrices, indicating that reduction of compound concentration after wastewater treatment as well as dilution factor once pharmaceuticals are discharged in receiving river water efficiently mitigate possible environmental hazards.

Analysis of anthelmintics in surface water by ultra high performance liquid chromatography coupled to quadrupole linear ion trap tandem mass spectrometry

Chemosphere, 2014

A method based on ultra high performance liquid chromatography coupled to quadrupole linear ion t... more A method based on ultra high performance liquid chromatography coupled to quadrupole linear ion trap mass spectrometry (UHPLC-QqLIT-MS) has been developed to investigate occurrence of 10 anthelmintic drugs from different structural groups (moxidectin, flubendazole, fenbendazole, levamisol, mebendazole, oxibendazole, albendazole, triclabendazole, febantel and praziquantel) in surface water. Analytes were pre-concentrated by solid phase extraction (SPE) using hydrophilic-lipophilic polymeric based sorbent. Quantification of investigated analytes was done using deuterated compounds as internal standards in order to minimize matrix effect. Analyte recoveries from spiked samples at two concentration levels were above 75% for most of the analytes. The main advantages of developed method are fast separation using UHPLC and therefore short analysis time, combined with good sensitivity which is demonstrated by low ngL(-1) detection limits. The developed method was applied for analysis of anthelmintics in the Llobregat River (NE Spain) and its main tributaries (rivers Anoia and Cardener). Eight out of ten anthelmintics were detected in all analyzed samples with the concentrations in low ngL(-1) level. The method fills the gap on analytical methodologies for determination of anthelmintic drugs in the environment.

Tracing Pharmaceutical Residues of Different Therapeutic Classes in Environmental Waters by Using Liquid Chromatography/Quadrupole-Linear Ion Trap Mass Spectrometry and Automated Library Searching

Analytical Chemistry, 2009

This article describes the development, optimization, and validation of an analytical method for ... more This article describes the development, optimization, and validation of an analytical method for the simultaneous detection and identification of 73 pharmaceutical residues, covering various therapeutic groups, in both surface and wastewaters. The method is based on the simultaneous extraction of all target compounds by Solid Phase Extraction (SPE), using a hydrophilic-lipophilic balanced polymer followed by liquid chromatography tandem mass spectrometry, using a hybrid triple quadrupole-linear ion trap mass spectrometer (QqLIT). Quantitative analysis was performed using the 4000 Qtrap tandem mass spectrometer in Selected Reaction Monitoring (SRM) mode, monitoring two SRM transitions to fulfill EC guidelines, as well as to ensure an accurate identification of target compounds in the samples. Quantitation is performed by the internal standard approach, indispensable to correct matrix effects. Moreover, to obtain an extra tool for confirmation and identification of the studied pharmaceuticals, an Information Dependent Acquisition (IDA) experiment was performed, with SRM as the survey scan and an enhanced product ion (EPI) scan, at three different collision energies, as dependent scan. Compound identification was carried out by library search with a developed library, created by the infusion of standards, based on EPI spectra at the three collision energies. The main advantages of the developed method, besides high sensitivity (limits of detection ranging from 0.1-55 ng/L, depending on the matrix), selectivity, and reliability of results, are that all compounds are extracted in a single step, speeding up considerably sample preparation. Recoveries obtained were generally higher than 50% for both surface and wastewaters, with the exception of metronidazole (20-30%), salbutamol (33-43%), atorvastatin (40% in surface water), and nadolol (31% in surface water) that yielded lower but still acceptable recoveries. The overall variability of the method was below 15%, for all compounds and all matrixes tested. Finally, the method developed has been applied to the analysis of various influent and effluent wastewaters as well as river waters from Spain.

Biodegradation of the X-ray contrast agent iopromide and the fluoroquinolone antibiotic ofloxacin by the white rot fungus Trametes versicolor in hospital wastewaters and identification of degradation products

Water research, 2014

This paper describes the degradation of the X-ray contrast agent iopromide (IOP) and the antibiot... more This paper describes the degradation of the X-ray contrast agent iopromide (IOP) and the antibiotic ofloxacin (OFLOX) by the white-rot-fungus Trametes versicolor. Batch studies in synthetic medium revealed that between 60 and 80% of IOP and OFLOX were removed when spiked at approximately 12 mg L(-1) and 10 mg L(-1), respectively. A significant number of transformation products (TPs) were identified for both pharmaceuticals, confirming their degradation. IOP TPs were attributed to two principal reactions: (i) sequential deiodination of the aromatic ring and (ii) N-dealkylation of the amide at the hydroxylated side chain of the molecule. On the other hand, OFLOX transformation products were attributed mainly to the oxidation, hydroxylation and cleavage of the piperazine ring. Experiments in 10 L-bioreactor with fungal biomass fluidized by air pulses operated in batch achieved high percentage of degradation of IOP and OFLOX when load with sterile (87% IOP, 98.5% OFLOX) and unsterile (6...