Biomedical subjects

A R Fernández-Alba

Publications and source records attributed to A R Fernández-Alba.

At least 19 recordsLinked to original sources

PubMed2006

LC-MS analysis and environmental risk of lipid regulators.

This article presents a review of liquid chromatography-mass spectrometric (LC-MS) methods applied to the determination of lipid-regulating agents, "fibrate" and "statin" classes, and some of their metabolites (clofibric acid and fenofibric acid) in environmental samples. Concentration levels of this therapeutical group have been reported in the ppt to ppb range for different compartments (wastewater, surface water and sediments) in several monitoring studies. Part of this article is dedicated to hazard assessment of lipid-regulating agents according to the approaches of the European Union (EU) and Environmental Protection Agency (EPA) for identifying persistent, bioaccumulable and toxic (PBT) substances. The pharmacodynamic and pharmacokinetic activities of these pharmaceuticals are well known and, based on this information, the derivation of the potential long-term effects, which may be induced on eco-organisms at low concentration levels, is discussed. Studies of environmental risk assessment (ERA) for lipid regulators carried out through the framework of the European Agency for the Evaluation of Medicinal Products (EMEA) and Food and Drug Administration (FDA) are presented.

Animals↗

PubMed2006

Pilot survey monitoring pharmaceuticals and related compounds in a sewage treatment plant located on the Mediterranean coast.

A one-year monitoring study was performed to evaluate the occurrence, persistence and fate of a group of 14 organic compounds in a sewage treatment plant (STP) located in the south of Spain. These results are part of a more extensive study, financed by the Spanish Ministry of Research with the aim to evaluate the traceability of new pollutants on the Mediterranean coast and to determine the removal efficiency of sewage treatment plants (STP) for these pollutants. The compounds which have been analyzed include pharmaceuticals of various therapeutic categories (ibuprofen, acetaminophen, dipyrone, diclofenac, carbamazepine and codeine), pesticides (chlorfenvinfos and permethrin), caffeine, triclosan, bisphenol A and three of their more relevant metabolites (1,7-dimethylxanthine, carbamazepine 10,11-epoxide and 2,7/2,8-dichlorodibenzo-p-dioxin). An SPE/GC-MS multi-residue analytical method was developed and validated to facilitate simultaneous determination of these compounds in both influent and effluent wastewater. The method provided mean recoveries higher than 75%, with the exception of 2,7/2,8-dichlorodibenzo-p-dioxin, dipyrone and permethrin which exhibited recoveries lower than 22%. The overall variability of the method was below 14%. The method detection limit (LOD) was between 1 and 100 ng l(-1) and precision, which was calculated as relative standard deviation (RSD), ranged from 1.8% to 11.2%. The application of the proposed method has allowed the identification of all the target compounds at mean concentrations which ranged from 0.12 to 134 microg l(-1) in the influent and from 0.09 to 18.0 microg l(-1) in the effluent. The removal efficiencies of the STP for these compounds varied from 20% (carbamazepine) to 99% (acetaminophen), but in all cases resulted insufficient in order to avoid their presence in treated water and subsequently in the environment.

Environmental Monitoring↗

PubMed2006

Application of gas chromatography-hybrid chemical ionization mass spectrometry to the analysis of diclofenac in wastewater samples.

Hybrid chemical ionization (HCI), a new and useful alternative to conventional chemical ionization mass spectrometry, has been applied to the analysis of the pharmaceutical diclofenac in wastewater samples. This technique takes advantage of the high versatility of ion trap (IT) spectrometers combined with external ionization sources. In hybrid configuration, reagent ions are generated in the external source through electron ionisation (EI) of a reagent gas. These reagent ions are then drawn into the ion trap and only those selected are allowed to react with analytes eluting from the GC column. These ion-molecule reactions create analyte ions which are held in the ion trap. In this study ion-molecule reactions between C(3)F(5)(+) cations, generated from perfluorotributylamine (FC43), and diclofenac molecules have been investigated. The observed reaction products were [M+C(3)F(5)-H(2)O](+) adduct ions, which result from the initial electrophilic addition of C(3)F(5)(+) cations to the diclofenac molecule followed by the rapid loss of H(2)O. Further fragmentation of these ions by MS/MS yielded enough daughter ions for a reliable identification of diclofenac in complex matrices. The GC-HCI-MS/MS method applied to wastewater samples provided highly enhanced selectivity and sensibility, with a detection limit in real samples of 3.0 ng/L, for a solid-phase extraction (SPE) pre-concentration factor of 400. Other performance characteristics of the method, such as linearity and precision were also satisfactory. Finally, the method was successfully applied to the analysis of wastewater samples taken from the effluent of an urban sewage treatment plant (STP).

Chromatography, Gas↗

PubMed2006

Photolysis and photocatalysis of bisphenol A: identification of degradation products by liquid chromatography with electrospray ionization/time-of-flight/mass spectrometry (LC/ESI/ToF/MS).

Bisphenol A is a commonly known endocrine-disrupting compound detected in environmental water samples. The persistence of this compound has been studied by photolysis and photocatalysis studies. In this work, several experiments were performed in order to identify the degradation products under various conditions and in different types of matrices (deionized and waste water). These studies included the influence of sodium hypochlorite (NaClO), commonly present in drinking water, on the generation of chlorine by-products of bisphenol A. The effect of catalyses in solar degradation studies was evaluated as well. The identification of the degradation products was accomplished by liquid chromatography/time-of-flight/mass spectrometry (LC-ToF-MS), which provided highly selective information about elemental compositions. Accurate mass measurements for three main degradation products permitted the postulation of proposed empirical formula in this study. Some of the degradation products were formed in waste water matrices, thus suggesting their potential presence in environmental conditions and in drinking water.

Benzhydryl Compounds↗

PubMed2005

Application of time-of-flight mass spectrometry to the analysis of phototransformation products of diclofenac in water under natural sunlight.

Exact mass capabilities of time-of-flight (TOF) mass spectrometry along with other mass spectrometric techniques have been evaluated to elucidate a complete range of dichlofenac phototransformation products. Photolysis experiments with diclofenac in water under direct solar irradiation were performed to characterise the main phototransformation products generated and to determine their stability. Photolysis experiments were performed in both demineralised water and reconstructed standard freshwater. Samples were extracted before analysis by solid phase extraction (SPE) with Oasis HLB and MAX cartridges. Separation and identification of the transformation products were accomplished by the combined use of gas chromatography-mass spectrometry (GC/MS) and liquid chromatography coupled with time-of-flight mass spectrometry (LC/TOFMS). Both techniques provided complementary information that enabled the identification of 13 phototransformation products. Six of them were identified by GC/MS through the structural information provided by the full scan mass spectra obtained under electron impact (EI) ionisation and the confirmation of the molecular mass provided by positive chemical ionisation (PCI) analyses. Accurate mass measurements obtained by LC/TOFMS provided the elucidation of seven polar transformation products. The low mass error observed (<2 ppm) enabled the assignment of highly probable empirical formulas as well as identification of a process dimerisation route. The photoproducts identified demonstrated that photolysis of diclofenac occurs by two main routes. One is the consequence of the initial photocyclisation of diclofenac into carbazole derivatives. The other route goes through the initial decarboxilation of diclofenac and further oxidation of the alkyl-chain, which are typical photolytic process reactions. The main photoproduct identified was 8-chloro-9H-carbazole-1yl-acetic acid.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2004

Comparative study of analytical methods involving gas chromatography-mass spectrometry after derivatization and gas chromatography-tandem mass spectrometry for the determination of selected endocrine disrupting compounds in wastewaters.

Two GC-MS methods, based on the application of N,O-bis(trimethylsilyl)trifluoroacetamide-derivatization-GC-MS (selected-ion monitoring) and GC-MS-MS without derivatization, respectively, were optimised and applied to the determination of a group of five selected endocrine disrupting compounds (EDCs) in wastewaters. Both methods included solid-phase extraction with Oasis HLB cartridges allowing an enrichment factor for wastewater samples of 100-fold. The investigated EDCs were estrone, 17beta-estradiol, 17alpha-ethynylestradiol, 4-tert-octylphenol and bisphenol A. Results obtained from the validation studies yielded comparable results in both cases. Recoveries in spiked wastewaters at 50 ng/l were higher than 90% for all the compounds, except for 4-tert-octylphenol (75%). Repeatability and reproducibility were adequate, varying from 1.6 to 14%, except for estrone which reproducibility was 28% when the derivatization-GC-MS method was applied. Limits of detection calculated ranged from 2.5 to 27.5 ng/l with differences between both methods from 1.1 (estrone) to 10.4 (bisphenol A) times. Both methods were successfully applied to the analysis of the target compounds in sewage treatment plant influents and effluents. Traces of bisphenol A, 4-tert-octylphenol, estrone and 17beta-estradiol were detected at concentration levels ranging from 13.3 to 1105.2 ng/l.

Endocrine Glands↗

PubMed2004

Analysis by liquid chromatography-electrospray ionization tandem mass spectrometry and acute toxicity evaluation for beta-blockers and lipid-regulating agents in wastewater samples.

This paper describes a multiresidue method for the extraction and determination of two therapeutic groups of pharmaceuticals, lipid-regulating agents (clofibric acid, bezafibrate, gemfibrocil, fenofibrate) and beta-blockers (atenolol, sotalol, metoprolol, betaxolol) in waters by solid-phase extraction followed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS). Recoveries obtained from spiked HPLC water, as well as, from spiked real samples (sewage treatment plants influent and effluents, river and tap water) were all above 60%, with the exception of betaxolol with a 52% recovery. The quantitative MS analysis was performed using a multiple reaction monitoring. The LC-MS-MS method gave detection limits ranging from 0.017 to 1.25 microg/l in spiked effluent. Precision of the method, calculated as relative standard deviation, ranged from 3.7 to 18.5%. Individual and combined effects on Daphnia magna were evaluated for both therapeutic groups. Individual effects in culture medium showed these compounds as not harmful and not toxic, an exception is fenofibrate that was found to be harmful, but at high, in the environment unrealistic concentrations (EC50 of 50 mg/l). Combined effect in wastewater showed synergistic toxic effects at low concentration level (2 microg/l).

Adrenergic beta-Antagonists↗

PubMed2003

Photocatalytic treatment of diuron by solar photocatalysis: evaluation of main intermediates and toxicity.

The technical feasibility, mechanisms, and performance of degradation of aqueous diuron (22 mg/L) have been studied at pilot scale in two well-defined photocatalytic systems of special interest because natural UV light can be used: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. Equivalent pilot-scale (made up of Compound Parabolic Collectors (CPCs) specially designed for solar photocatalytic applications) and field conditions used for both allowed adequate comparison of the degree of mineralization and toxicity achieved as well as the transformation products generated en route to mineralization by both systems. Total disappearance of diuron is attained by both phototreatments in 45 min. 100% of chlorine was recovered as chloride, but total recovery of nitrogen as inorganic ions was not attained. 90% of mineralization was reached after 200 min of photocatalytic treatment, but toxicity measured by two different bioassays (Daphnia magna and a Microalga) was reduced to below the threshold (EC50%) in a shorter time. Transformation products evaluated by LC-IT-MS by direct injection of the samples were the same in both cases. The main differences between the two processes were in the amount of transformation products (DPs) generated, not in the DPs detected, which were always the same.

Animals↗

PubMed2003

Combined toxicity effects of MTBE and pesticides measured with Vibrio fischeri and Daphnia magna bioassays.

Methyl-tert-butyl ether (MTBE), a fuel oxygenate that is added to gasoline, commonly contaminates aquatic systems, many of which are already contaminated with pesticides. The toxic effects (EC(50) value) of several pure pesticides (Diuron, Linuron, Dichlofluanid, Sea nine, Irgarol and tributyltin (TBT)) were measured and compared with the EC(50) value of the pesticide mixed with MTBE, using the Vibrio fischeri and Daphnia magna acute toxicity assays. The interaction between chemicals was evaluated in terms of the effects of mixing on the EC(50) value (i.e. the concentration (mg/L) of a compound or mixture that is required to produce a 50% change in a toxic response parameter) and the time required to generate the toxic response. Presence of MTBE enhanced the EC(50) value of several pesticides (Diuron, Dichlofluanid, TBT and Linuron) and/or the toxic response manifested more rapidly than with pure pesticides. Toxicity enhancements were quite substantial in many cases. For example, the presence of MTBE increased the toxicity of Diuron by more than 50% when tested with the V. fischeri assay (5, 15 and 30 min exposure). Also, the toxic response manifested itself within 5 min whereas without the MTBE the same response arose in 30 min. Presence of MTBE increased the toxicity of Dichlofluanid by 30% when measured with the D. magna assay. Toxicities of only two pesticides (Sea nine and Irgarol) were not raised by the presence of MTBE.

Animals↗

PubMed2003

Photo-Fenton treatment of water containing natural phenolic pollutants.

Phenolic compounds are known to be present in high concentrations in various types of agro-industrial wastes. As they are highly biorecalcitrant, the possibility of treatment by advanced oxidation processes should be investigated. In this work, six model phenolic compounds (vanillin, protocatechuic acid, syringic acid, p-coumaric acid, gallic acid and L-tyrosine) were chosen for a demonstration of degradation by photo-Fenton reaction, under artificial light in laboratory experiments in Vienna and under sunlight in pilot-plant experiments at the Plataforma Solar de Almería in Spain. All compounds were completely mineralised. No non-degradable intermediates were produced, either in experiments with single substances or in a more complex matrix of a mixture of phenolic compounds. The expected selectivity of the photo-Fenton reaction for aromatic compounds was proven by comparison of the decrease in total organic carbon with the removal of total phenolic content.

Hydrogen Peroxide↗

PubMed2002

Toxicity of single and mixed contaminants in seawater measured with acute toxicity bioassays.

Different types of organic pollutants commonly detected in seawater have been evaluated by acute toxicity bioassays. Vibrio fischeri, Daphnia magna, and Selenastrum capricornotum were selected to test toxic effects of individual compounds and mixtures of these compounds, obtaining EC50 values in the range of 0.001 to 28.9 mg/l. In the case of mixtures, synergistic toxic responses were seen for a clear majority of the cases (>60%). Mixtures containing methyl-tertiary-butyl ether (MTBE) exhibit accelerated processes that result in a change in concentration required to produce a toxic effect; for example, in the case of mixtures containing MTBE and Diuron and Dichlofluanid.

Animals↗

PubMed2002

Toxicity assays: a way for evaluating AOPs efficiency.

The technical feasibility and performance of photocatalytic degradation of aqueous methomyl (50 mg/L) have been studied at pilot scale in two well-defined systems of special interest because natural-solar UV light can be used: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. The pilot plant is made up of compound parabolic collectors specially designed for solar photocatalytic applications. Experimental conditions allowed pesticide disappearance, degree of mineralisation and toxicity achieved in the two photocatalytic systems to be compared. Total disappearance of methomyl is attained by photo-Fenton in 60 min and by TiO2 in 100 min. Hundred percent of nitrogen and sulphur are recovered as ammonium and sulphate. By contrast, complete mineralisation of total organic carbon (TOC) is not achieved even after quite a long time (more than 300 min). Three different bioassays (Vibrio fischeri, Daphnia magna and a Microalga) have been used for testing the progress of toxicity during treatment. All remained toxic down to very low-pesticide concentrations and in some bioassays were still toxic after total disappearance of the pesticide. Only if treatment is maintained throughout enough mineralisation (i.e. TOC disappearance), the toxicity is reduced to below the threshold (EC50%).

Animals↗

PubMed2001

Determination of traces of five antifouling agents in water by gas chromatography with positive/negative chemical ionisation and tandem mass spectrometric detection.

A highly selective and sensitive gas chromatography-mass spectrometry methodology has been developed for the determination of five antifouling compounds, currently licensed for use in marine antifouling paints. The procedure uses an ion trap mass spectrometer provided with an external ion source that allows the combined use, in the same analysis, of positive (PCI) and negative (NCI) chemical ionisation and tandem mass spectrometric fragmentation (MS-MS). Ionisation and fragmentation processes were optimised individually for each compound, thus, permitting maximum sensitivity and selectivity to be obtained. A complete validation study, including those aspects that affect both correct quantification and unequivocal confirmation, demonstrated the good performance of the proposed method. Detection limits obtained were lower than 0.005 microg l(-1), except for Irgarol 1051 (0.050 microg l(-1)). The method was applied to real seawater samples from different

Fungicides, Industrial↗

PubMed2001

Degradation of imidacloprid in water by photo-Fenton and TiO2 photocatalysis at a solar pilot plant: a comparative study.

The technical feasibility, mechanisms, and performance of degradation of aqueous imidacloprid have been studied at pilot scale in two well-defined photocatalytic systems of special interest because natural UV light can be used: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. Equivalent pilot-scale and field conditions used for both allowed adequate comparison of the degree of mineralization and toxicity achieved as well as the transformation products generated in route to mineralization by both systems. Ninety-five percent of mineralization (<2.0 mg/L) was reached after 250 min of photocatalytic treatment with Fenton and 450 min with TiO2, meaning that TOC disappears 2.4 times faster with photo-Fenton photocatalytic treatment than with TiO2. The Daphnia Magna test for final residual TOC does not reveal anytoxic behavior. Transformation products evaluated by GC-MS/AED after two SPE procedures and LC-IC were the same in both cases. The main differences between the two processes are in the amount of transformation products (TPs) generated, not in the TPs detected which were always the same. At the end of both processes low concentration (<0.1 mg/L) of 2 pyrrolidinone (transformation product) remains in the dissolution and around 1 mg/L of formate in the case of photo-Fenton.

Ferric Compounds↗

PubMed2001

Gas chromatographic determination of pesticides in vegetable samples by sequential positive and negative chemical ionization and tandem mass spectrometric fragmentation using an ion trap analyser.

A selective and sensitive chromatographic method is described for the determination of nine organochlorine and organophosphorus pesticides in vegetable samples by gas chromatography-mass spectrometry. The proposed method combines the use of positive and negative chemical ionisation and tandem mass spectrometric fragmentation, resulting in a significant increase in selectivity and allowing the simultaneous confirmation and quantification of trace levels of pesticides in complex vegetable matrices. Parameters relative to ionisation and fragmentation processes were optimised to obtain maximum sensitivity. Repeatability and reproducibility studies yielded relative standard deviations lower than 25% in all cases. Identification criteria, such as retention time and relative abundance of characteristic product ions, were also evaluated in order to guarantee the correct identification of the target compounds. The method was applied to real vegetable samples to demonstrate its use in routine analysis.

Gas Chromatography-Mass Spectrometry↗

PubMed2001

Occurrence of antifouling biocides in the Spanish Mediterranean marine environment.

A compilation of the results of a monitoring program of the recently used antifouling pesticides diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea), Irgarol 1051 (2-methylthio-4-tertiary-butylamino-6-cyclopropylamino-s-teiazine), seanine 211 (4,5-dichloro-2-n-octyl-4-isothazolin-3-one), chlorothalonil (2,4,5,6-tetrachloro-isophthalonitrile), dichlofluanid (N'-dimethyl-N-phenylsulphanamide), TCMTB ((2-thiocyanomethylthio) benzothiazole), and three degradation products demethyldiuron (3-(3,4-dichlorophenyl)-1-methylurea),3,4-dichlorophenylurea and 2-methylthio-4-tert-butylamino-s-triazine (Irgarol degradation product) that was carried out between April 1996 and February 2000 in enclosed seawaters from Catalonia and Almería (Spanish Mediterranean coast) is reported. Nine points were sampled along the Catalan coast: Barcelona Olympic port, Masnou, Blanes, Sant Carles de la Ràpita, Tarragona, Cambrils and Salou marinas as well as the Cambrils and Tarragona fishing harbors and in marinas and ports from Almeria: Aguadulce port, Almería port, Almerimar fishing harbour and Almerimar marina. The analytical methodologies were based on Solid Phase Extraction followed by liquid chromatography (LC) or gas chromatography (GC) coupled to a mass spectrometry (MS) or -Diode Array Detector. The main pollutants found in the sampled points were diuron and Irgarol 1051 that were detected at concentrations up to 2.19 micrograms l-1 and 0.33 microgram l-1, respectively. On the other hand, seanine 211 was found at the highest concentration (up to 3.7 micrograms l-1) during the summer of 1999. Low concentrations of dichlofluanid and the above mentioned degradation products were detected for the first time in the Spanish coasts. Chlorothalonil, TCMTB were not found at concentrations higher than 1 and 20 ng l-1 respectively which were the limit of determination (LOD) of the method for these compounds. In general the contamination at the different marinas is higher at the end of spring and in summer where the boating activity is also higher. This paper shows for the first time that the contamination by the new antifouling pesticides in Spanish coastline, basically marinas and fishing harbours, is permanent along the whole calendar year. So, preventive actions by the harbour authorities will be needed in the near future in order to monitor and control the levels and effects of the new antifouling biocides in the marine environment.

Chromatography, High Pressure Liquid↗

PubMed2000

Multiresidue method for the analysis of five antifouling agents in marine and coastal waters by gas chromatography-mass spectrometry with large-volume injection.

A simple multiresidue method has been developed for the determination of five pesticides, commonly used as active ingredients in antifouling paints, in seawater samples. The pesticides studied were: chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile), dichlofluanid (N-dimethyl-N-phenylsulphamide), Sea-Nine 211 (4,5-dichloro-2-n-octyl-4-isothazolin-3-one), Irgarol 1051 (2-methylthio-4-tert.-butylamino-6-cyclopropylamino-s-triazine) and TCMTB (2-thiocyanomethylthiobenzothiazole). The analytes were extracted from 200 ml water samples, using solid-phase extraction. A copolymer with hydrophilic-lipophilic balance was used as sorbent yielding good recoveries (82-95%) for most compounds except dichlofluanid and Sea-Nine 211 (<60%). Large volume injection (10 microl) gas chromatography and electron impact ionization MS (selected ion monitoring mode) detection enabled these compounds to be identified and quantified at the 1.2-3.0 ng/l level. Analysis of samples performed in three marinas in Almería (Spain) revealed the presence of Irgarol 1051 in all the cases, at concentration levels between 25 and 450 ng/l.

Aniline Compounds↗

PubMed2000

Solar photocatalytic mineralization of commercial pesticides: acrinathrin.

A comparative study of the degradation of commercial acrinathrin spiked in water using TiO2 photocatalysis and photolysis under sunlight was performed. Samples were analysed by liquid chromatography-diode array detector (HPLC-DAD) and gas chromatography-ion trap-mass spectrometric detector (GC-ITMS). Additional total organic carbon (TOC) analyses were carried out to evaluate the mineralisation rates. One photoproduct, 2-phenoxy benzaldehyde, was unequivocally identified and evaluated by GC-ITMS during the processes. Although acrinathrin is almost destroyed when exposed to irradiation for more than 400 h, photocatalysis with TiO2 noticeably reduced degradation to a few hours. In this case, with the additional presence of peroxydisulphate, in less than 2 h acrinathrin is completely destroyed. Mineralisation of acrinathrin, without catalyst, was only around 50% after 400 h of irradiation.

Catalysis↗