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ABSTRACT: Benzodiazepines are widely consumed psychiatric pharmaceuticals which are frequently detected in the environment. The environmental persistence and fate of these pharmaceuticals as well as their degradation products is of high relevance and it is, yet, scarcely elucidated. In this study, the relevance of photodegradation processes on the environmental persistence of four benzodiazepines (oxazepam, diazepam, lorazepam and alprazolam) was investigated. Benzodiazepines were irradiated under simulated solar irradiation and direct and indirect (together with three different fractions of humic substances) photodegradation kinetics were determined. Lorazepam was shown to be quickly photodegradated by direct solar radiation, with a half-life time lower than one summer sunny day. On the contrary, oxazepam, diazepam and alprazolam showed to be highly resistant to photodegradation with half-life times of 4, 7 and 228 summer sunny days, respectively. Apparent indirect and direct photodegradation rates are of the same order of magnitude. However, humic acids were consistently responsible for a decrease in the photodegradation rates while fulvic acids and XAD4 fraction caused an enhancement of the photodegradation. Overall, the results highlight that photodegradation might not be an efficient pathway to prevent the aquatic environmental accumulation of oxazepam, diazepam and alprazolam. Also, nineteen direct photodegradation products were identified by electrospray mass spectrometry, the majority of which are newly identified photoproducts. This identification is crucial to a more complete understanding of the environmental impact of benzodiazepines in aquatic systems.
Water Research 09/2011; 45(18):6097-106. · 4.86 Impact Factor
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ABSTRACT: In this study, a simple and rapid procedure for monitoring adsorption of 17α-ethynylestradiol (EE2) onto soil samples was developed. The used method is based on a multiwavelength fluorescence spectral deconvolution (FSD) where the emission fluorescence spectrum of a sample is considered as a linear combination of emission spectra, named reference spectra. The combination of the reference spectra allows the restitution of the shape of the emission spectrum of any unknown sample. This approach was applied to follow EE2 adsorption onto four soil samples and is an easy and low cost alternative. Adsorption experimental data showed a good fit with the Hill equation, mathematically equivalent to the Langmuir-Freundlich model assuming that the adsorption is a cooperative process influenced by adsorbate-adsorbate interactions. Molecular modelling studies clearly support the "co-operative adsorption" model, showing that after the adsorption of the first layer of EE2 molecules onto the soil, at least one more layer of EE2 is adsorbed, due to interactions established with the first adsorbed layer. Notwithstanding, packing a third row would imply interactions between two EE2 molecules that differ from the ones verified in the lowest energy structure, which also explains the plateau achieved in the adsorption curve.
Chemosphere 05/2011; 84(8):1072-8. · 3.21 Impact Factor
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ABSTRACT: Carbamazepine is a psychiatric pharmaceutical widely detected in aquatic environments. Due to its generalized occurrence and environmental persistence it might be considered as an anthropogenic pollution indicator. In this research, a previously developed enzyme-linked immunosorbent assay (ELISA), based on a commercial monoclonal antibody, was applied to the quantification of carbamazepine in ground, surface and wastewaters and results were validated by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The performance of the applied ELISA methodology was tested in the presence of high concentrations of sodium chloride and dissolved organic matter. The method was not significantly affected by matrix effects, being adequate for the quantification of carbamazepine in environmental samples, even without sample pre-treatment. This method allows the quantification of carbamazepine in the range of 0.03-10 μg L(-1), with a relative error lower than 30%. Due to a pH dependent cross-reactivity with cetirizine, an antihistaminic drug, the assay also enabled the quantification of cetirizine in the samples. The application of the developed method to the quantification of carbamazepine was performed by using environmental samples with very different matrices, collected in the geographical area of Ria de Aveiro, an estuarine system located in the North of Portugal. Carbamazepine was detected in all analyzed wastewater samples and in one surface water with concentrations between 0.1 and 0.7 μg L(-1). Validation with LC-MS/MS revealed that results obtained by ELISA are 2-28% overestimated, which was considered highly satisfactory due to the absence of sample pre-treatments.
Chemosphere 05/2011; 84(11):1708-15. · 3.21 Impact Factor
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ABSTRACT: Carbamazepine, a widely consumed psychotropic pharmaceutical, is one of the most commonly detected drugs in the environment. To better assess the environmental persistence of carbamazepine in aqueous matrices, the effect of pH and dissolved oxygen on the direct photodegradation rate of this pharmaceutical was evaluated in this study, using simulated solar irradiation. In order to follow the degradation and the emergence of photoproducts, a micellar electrokinetic chromatography based method was developed, consisting on the use of a dynamically coated capillary column. The developed methodology showed good repeatability and efficiency in the separation of carbamazepine and photoirradiation products. Also, seven photodegradation products were identified by electrospray mass spectrometry (ESI-MS), including the known carcinogenic acridine that was produced under all the pH and oxygenation levels studied and one newly identified photoproduct. This paper gives new insights into the role of dissolved oxygen on the photodegradation rate of carbamazepine. The results indicate that acidic pH, combined with the absence of dissolved oxygen in the aqueous matrix, results in very high direct photodegradation rates. At basic pH, dissolved oxygen does not interfere with the process and very low rates were observed. At environmentally relevant conditions, carbamazepine was shown to persist in the environment from 4.5 to 25 days.
Water Research 01/2011; 45(3):1095-104. · 4.86 Impact Factor
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ABSTRACT: Three novel large polyazamacrocycles containing two 1,10-phenanthroline units connected by different polyamine spacers have been synthesised and their protonated forms used as receptors for several aromatic carboxylate anions. The receptors bind to the anions in a 1:1 stoichiometry and exhibit remarkable binding selectivity (see figure). Analysis shows that molecular recognition is governed by pi-pi stacking interactions and multiple N--HO==C hydrogen bonds.Three novel large polyazamacrocycles containing two 1,10-phenanthroline (phen) units connected by two polyamine spacers of different length, [32]phen(2)N(4), [30]phen(2)N(6) and Me(2)[34]phen(2)N(6), have been synthesised and their protonated forms used as receptors for binding studies with several aromatic carboxylate anions (benzoate (bzc(-)), 1-naphthalate (naphc(-)), 9-anthracenate (anthc(-)), pyrene-1-carboxylate (pyrc(-)), phthalate, (ph(2-)), isophthalate (iph(2-)), terephthalate (tph(2-)), 2,5-dihydroxy-1,4-benzenediacetate (dihyac(2-)) and, 1,3,5-benzenetricarboxylate (btc(3-))) and three herbicides (4-amino-3,5,6-trichloropyridine-2-carboxylate (ATCP(-)), dichlorophenoxyacetate (2,4-D(-)) and glyphosate (PMG(2-))) in water solution. The [30]phen(2)N(6) receptor was found to be the most suitable for binding the anions considered in a 1:1 stoichiometry. The three receptors exhibit a remarkable binding selectivity towards the extended aromatic anion pyrc(-) at low pH values. Their binding affinities for the monocarboxylate anions decrease with the extension of the aromatic system in the order pyrc(-)>anthc(-)>naphc(-)>bzc(-), which indicates the presence of pi-pi stacking interactions in the molecular recognition of these anions. Molecular dynamics simulations carried out for the binding of {H(4)[30]phen(2)N(6)}(4+) and {H(6)Me(2)[34]phen(2)N(6)}(6+) with pyrc(-), anthc(-), naphc(-), iph(2-) and btc(3-) in water showed that these receptors adopt a folded conformation with the anion inserted between the two phen heads and that the molecular recognition is governed by pi-pi stacking interactions and multiple N--HO==C hydrogen bonds. The binding free energies estimated theoretically are very similar to those found by potentiometric methods, which supports the proposed binding arrangement.
Chemistry 02/2009; 15(13):3277-89. · 5.93 Impact Factor
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ABSTRACT: Psychiatric pharmaceuticals, such as anxiolytics, sedatives, hypnotics, and antidepressants, are among the most prescribed active substances throughout the world. The occurrence of these widely used compounds in environmental matrices (wastewaters, surface, ground and drinking waters, soils, sediments, bio-solids and tissue), as well as the first studies indicating their high persistence and toxicity to non-target organisms, justify the growing concern about these emerging environmental pollutants. Despite this increasing interest, there is a considerable lack of knowledge about the environmental fate of a large number of psychiatric pharmaceuticals and further research about this topic is needed. This paper aims to review the literature data related to the occurrence, persistence, environmental fate and toxicity for non-target organisms of this group of pharmaceuticals. The analytical methods developed for the determination of psychiatric medicines in environmental matrices are also highlighted.
Chemosphere.
