Monday 27 April 2015

Cleavage of carbofuran and carbofuran-derivatives in micellar aggregates

Progress in Reaction Kinetics and Mechanism, 40 (2015) 105-118

In recent years, the stability of carbamate pesticides have been studied by our research group in a wide range of biomimetic microheterogeneous media such as micelles or reverse micelles. These microheterogeneous media included different surfactant species and, hence, different self-assembled structures. In particular, basic hydrolysis of carbofuran and its derivatives have been analysed in the presence of anionic, cationic, non-ionic and reverse micelles. The results obtained from these physicochemical and kinetic studies, as well as a consistent comparison of them, are now summarised.

Monday 13 April 2015

Evaluation of the effect of fenhexamid and mepanipyrim in the volatile composition of Tempranillo and Graciano wines

Food Research International
Volume 71, May 2015, Pages 108–117

Grapes from Vitis vinifera var. Tempranillo and Graciano of La Rioja (North Central Spain) were vinified after addition of two fungicides (mepanipyrim and fenhexamid) at concentrations corresponding to their MRLs. These fungicides are commonly used in the vine growing to control botrytis disease. The fungicide effect throughout winemaking on the volatile composition and aroma profile of the final wines was evaluated, together with the level of fungicide residues in the final wines that were found to be safe for consumers. Concentrations of C13-norisoprenoids in Graciano wines obtained after the addition of both active substances showed the greatest variations with respect to control wine; whereas the concentration of volatile compounds in Tempranillo wines were seemingly unaffected by the presence of fungicide residues. On the other hand, the aroma profile of monovarietal red wines was evaluated by using odorant series which included volatile compounds with similar odour descriptors. In this sense, supplementation with the antifungals seemed to increase the OAV for the ripe fruit series with respect to the control wines in Graciano wines.

Saturday 11 April 2015

Perspectives on the use of by-products to treat soil and water pollution

Microporous and Mesoporous Materials
Volume 210, 1 July 2015, Pages 199–201

The use of modified by-products in pollution removal is conceptually very interesting, as shown in a paper by Peng et al. (2015) recently published in Microporous and Mesoporous Materials. However, we would like to stimulate a debate on the convenience of simultaneously continuing to research on the purging potential of raw by-products and waste materials.

Friday 10 April 2015

Kinetics of tetracycline, oxytetracycline, and chlortetracycline adsorption and desorption on two acid soils

Environmental Science and Pollution Research
January 2015, Volume 22, Issue 1, pp 425-433

The purpose of this work was to quantify retention/release of tetracycline, oxytetracycline, and chlortetracycline on two soils, paying attention to sorption kinetics and to implications of the adsorption/desorption processes on transfer of these pollutants to the various environmental compartments. We used the stirred flow chamber (SFC) procedure to achieve this goal. All three antibiotics showed high affinity for both soils, with greater adsorption intensity for soil 1, the one with the highest organic matter and Al and Fe oxides contents. Desorption was always <15 %, exhibiting strong hysteresis in the adsorption/desorption processes. Adsorption was adequately modeled using a pseudo first-order equation with just one type of adsorption sites, whereas desorption was better adjusted considering both fast and slow sorption sites. The adsorption maximum (q max ) followed the sequence tetracycline > oxytetracycline > chlortetracycline in soil 1, with similar values for the three antibiotics and the sequence tetracycline > chlortetracycline > oxytetracycline in soil 2. The desorption sequences were oxytetracycline > tetracycline > chlortetracycline in soil 1 and oxytetracycline > chlortetracycline > tetracycline in soil 2. In conclusion, the SFC technique has yielded new kinetic data regarding tetracycline, oxytetracycline, and chlortetracycline adsorption/desorption on soils, indicating that it can be used to shed further light on the retention and transport processes affecting antibiotics on soils and other media, thus increasing knowledge on the behavior and evolution of these pharmaceutical residues in the environment.

Tuesday 7 April 2015

Effect of crushed mussel shell addition on bacterial growth in acid polluted soils

Applied Soil Ecology
Volume 85, January 2015, Pages 65–68

We applied three different doses of crushed mussel shell (CMS) on two Cu-polluted acid soils to study the effect of these amendments on the growth of the bacterial community during 730 days. Soil pH increased in the short and medium term due to CMS addition. In a first stage, bacterial growth was lower in the CMS-amended than in the un-amended samples. Thereafter, bacterial growth increased slowly. The soil having the highest initial pH value (4.5) showed the first significant increase in bacterial growth 95 days after the CMS amendment. However, in the soil with the lowest initial pH value (3.8) bacterial growth increased significantly only after 730 days from the CMS addition. The highest dose of CMS caused that, at the end of the incubation period, pH value have increased 2 units, whereas bacterial growth was 4–10 times higher. In view of these results, CMS amendment could be considered as an agronomic sound practice for strongly acid soils (pH <4.5).

Saturday 4 April 2015

Adsorption, desorption and fractionation of As (V) on untreated and mussel shell-treated granitic material

Solid Earth, 6 (1) 337-346 (2015)

As(V) adsorption and desorption were studied on granitic material, coarse and fine mussel shell and granitic material amended with 12 and 24 t ha−1 fine shell, investigating the effect of different As(V) concentrations and different pH as well as the fractions where the adsorbed As(V) was retained. As(V) adsorption was higher on fine than on coarse shell. Mussel shell amendment increased As(V) adsorption on granitic material. Adsorption data corresponding to the unamended and shell-amended granitic material were satisfactory fitted to the Langmuir and Freundlich models. Desorption was always <19% when the highest As(V) concentration (100 mg L−1) was added. Regarding the effect of pH, the granitic material showed its highest adsorption (66%) at pH <6, and it was lower as pH increased. Fine shell presented notable adsorption in the whole pH range between 6 and 12, with a maximum of 83%. The shell-amended granitic material showed high As(V) adsorption, with a maximum (99%) at pH near 8, but decreased as pH increased. Desorption varying pH was always <26%. In the granitic material, desorption increased progressively when pH increased from 4 to 6, contrary to what happened to mussel shell. Regarding the fractionation of the adsorbed As(V), most of it was in the soluble fraction (weakly bound). The granitic material did not show high As(V) retention capacity, which could facilitate As(V) transfer to water courses and to the food chain in case of As(V) compounds being applied on this material; however, the mussel shell amendment increased As(V) retention, making this practice recommendable.

Wednesday 1 April 2015

Liquid chromatography–mass spectrometry method development for monitoring stress-related corticosteroids levels in pig saliva

Journal of Chromatography B
Volume 990, 15 May 2015, Pages 158–163

Biochemical response stressors results in an increase of adrenocortical activity. Before knowing the corticosteroid levels in saliva in a stressful situation, baselines salivary levels should be established. A method for simultaneous determination of five corticosteroids was developed, validated and applied to pig saliva at farms. The method employs solid-phase extraction (SPE) coupled with clean-up extraction step using silica cartridge in the same step followed by liquid chromatography/tandem mass spectrometry (LC–MS/MS), using electrospray ionization (ESI) in positive mode. The overall method quantification limits range from 0.050 to 0.30 μg/L for the enrichment of 1.0 mL saliva samples and analyte recoveries are between 60 and 90% (RSD < 11%). Some factors studied were: pig sex, breeds, and time at farm. The analytical method clearly shows that CRL and CRS levels of, respectively, 3.0 and 4.0 μg/L in saliva can be indicative of maxima non-stress levels in different pig breeds at farm.