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This work proposes an innovative non-destructive analytical strategy, based on Confocal Raman micro-spectroscopy, High Resolution Raman Imaging and micro-X-Ray Fluorescence imaging, as part of the quick non-destructive techniques that could be used to characterize the Martian samples from the Mars Sample Return mission when back on Earth. Until that moment, Martian Meteorites are the only Martian samples in our hands to develop such Analytical Strategies. To demonstrate its capabilities, this analytical strategy has been applied to characterize the Dar al Gani 735 Martian Meteorite with the aim to identify the terrestrial and non-terrestrial alterations suffered by the meteorite as a very valuable complementary methodology to the more traditional petrographic analyses and single point measurements. The combination of these techniques allows extracting at the same time elemental, molecular and structural information of the studied area of the sample. The most relevant results on the analyzed DaG 735 shergottite thick samples revealed the presence of several altered mineral phases originated from the temperature and pressure conditions during the shock on Mars (anhydride, calcite and ilmenite), as well as from terrestrial weathering processes that degraded the meteorite from its landing on Earth (calcite and hematite in fractures together with gypsum, mirabilite and thenardite). As most of the conclusive results come from Raman spectroscopy, this study shows the potential of Raman spectroscopy as a key technique in the upcoming new explorations of Mars materials by the Rosalind Franklin rover (Exomars2022 mission from ESA) and the Perseverance rover (Mars2020 mission from NASA), where Raman spectrometers are mounted for the first time in an extra-terrestrial research in the field., (Copyright © 2020. Published by Elsevier B.V.)

This work describes the development of an analytical procedure for the determination of short chain dicarboxylic acids (C2-C10) both in aqueous and solid matrices such as aerosols and mortars. The developed and validated methodology was based on the preconcentration of compounds by means of mixed-mode solid phase extraction and gas chromatography-mass spectrometry, regardless the analyzed samples. In the case of solid samples, a prior extraction of target compounds using ultrasonic probe-assisted solid-liquid extraction was required. In general terms, the developed procedure rendered good results in terms of accuracy (apparent recoveries in the range 90-130% and 86-98% for marine aerosol and mortar samples, respectively) and repeatability (%RSD < 25%) except for those compounds interacting more strongly with the solid matrix and being more reactive. The method was applied to detect dicarboxylic acids in marine aerosol water samples and in mortars of a 20th century historical building (Punta Begoña Galleries, Getxo) located in a coastal environment (Biscay Gulf, Basque Country, Northern Spain) with industrial activity. According to the results, harbor activities may have effect on the concentrations of dicarboxylic acids found in both matrices since the façade of the building exposed to the industrial harbor (southwest orientation) appears to be more contaminated than the one oriented to the northwest., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A new procedure based on ultrasound assisted dialysis (UAD) for the simultaneous and quantitative extraction of a wide number of persistent organic pollutants (POPs) such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) or some other organochlorinated pesticides (OCPs) contained in semi-permeable membrane devices (SPMDs) has been developed. This extraction technique combines the advantages of the organic solvent dialysis (OSD) and the speed of the ultrasound assisted extraction. The extraction was performed in an ultrasound bath for 32 min placing the SPMD in a glass flask covered with 80 mL of hexane. This set-up is able to extract simultaneously up to 8 samples. The proposed method entails good repeatabilities (RSD 2-13%) and recoveries (around 100% for almost every analyte). Limits of detection were at ng SPMD(-1) level and enough for the determination of the target analytes in a slightly polluted aquatic environment, as it was tested by successfully comparing the OSD to the proposed methodology. Therefore, the results obtained show that the UAD can be a good alternative for the extraction of POPs in SPMDs as it requires short extraction times and solvent volumes, and provides a cleaner extract for the subsequent clean-up step. Moreover, it fits better than the OSD to the general requirements of Green Chemistry., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The feasibility of partial least squares (PLS) regression modeling of X-ray fluorescence (XRF) spectra of estuarine sediments has been evaluated as a tool for rapid trace element content monitoring. Multivariate PLS calibration models were developed to predict the concentration of Al, As, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn, V and Zn in sediments collected from different locations across the estuary of the Nerbioi-Ibaizabal River (Metropolitan Bilbao, Bay of Biscay, Basque Country). The study was carried out on a set of 116 sediment samples, previously lyophilized and sieved with a particle size lower than 63 microm. Sample reference data were obtained by inductively coupled plasma mass spectrometry. 34 samples were selected for building PLS models through a hierarchical cluster analysis. The remaining 82 samples were used as a test set to validate the models. Results obtained in the present study involved relative root mean square errors of prediction varying from 21%, for the determination of Pb at hundreds microg g(-1) level, up to 87%, for Ni determination at little tens microg g(-1) level. An average prediction error of +/-37% for the 14 elements under study was obtained, being in all cases mean differences between predicted and reference results of the same order than the standard deviation of three replicates from a same sample. Residual predictive deviation values obtained ranged from 1.1 to 3.9., (Copyright (c) 2010 Elsevier B.V. All rights reserved.)

The 3051 USEPA method (or alternatively, the 3051A) can be considered nowadays as a reference method to extract metals from sediments. However, after microwave heating, the sample must be allowed to cool down, which results in a considerable lengthening of the whole analytical process. Microwave ovens and their maintenance are, in addition, expensive, and its use is relatively dangerous. The use of ultrasound focused energy to assist the extraction of chemicals from solid samples is a safe and relatively cheap technique. In this work we propose a new method to extract simultaneously several elements from sediments using ultrasound energy focused in a glass probe to accelerate the process, and check its possibilities to become an alternative to the EPA3051(A) approach. The optimised procedure allows extracting 13 elements in only 6 min, with similar recoveries and, in general, better repetitivities than the EPA3051. In addition, the suspension is only slightly heated during the leaching process.

Thermodynamic and Raman spectroscopic speciation was used to define the operating conditions for an innovative cleaning treatment of the decayed carbonate-based stones using ion exchange technology. The conditioning process of the Lewatit OC1071 anion exchanger with EDTA (Y) was monitored by ionic chromatography. Characterisation of the initial (R-Cl) and the final (R2-H2Y) forms of the ion exchanger was carried out by dispersive Raman microprobe spectroscopy. The subtraction spectrum obtained between the chloride and the EDTA forms of the ion exchanger shows Raman bands at 1403, 1324, 1223, 1122, 932, 908, 591, 431 and 350 cm(-1), which agree with bands showed in the spectrum of the standard solution of the H2Y(2-) species. Therefore, this seems to be the EDTA species which takes part in the cleaning treatment performed by using resin poultices on black crusted limestone samples from an historical building.

The thermodynamic model of inorganic arsenic was validated by comparing the predicted As(III) concentration with the experimentally determined one in several river waters samples of the Basque Country (Spain) collected in two sampling campaigns: spring and autumn 2000. This model takes into account the acid-base equilibria of As(III) and As(V) together with the redox equilibria between the H(3)AsO(3) and H(3)AsO(4) species. A correct prediction of As(III) concentration requires the knowledge of the total concentration of arsenic, pH, redox potential (referred to hydrogen electrode), and ionic strength values of the solution. The estimation of the activity coefficients of the arsenic species was performed by means of the Modified Bromley's Methodology (MBM). In order to perform the experimental As(III) determination, an analytical method was implemented by using an ion exchange separation of As(III)/As(V) on a continuous FIA-IE-HG-AAS system. The total arsenic concentration was determined together with total concentration of the main alkaline or alkaline-earth metals and anions in the natural waters. Temperature compensated measurements of the pH and redox potentials were made in-situ at the sampling sites. For both seasonal campaigns, the agreement between predicted and experimental As(III) is really high for those samples belonging to non polluted river waters.

Protonation constants of arsenic acid were determined at different ionic strengths in NaClO(4) (0.1, 0.5, 1.0, 3.0 mol dm(-3)), NaCl (0.5 and 1.0 mol dm(-3)) and KCl (0.5, 1.0 and 3.0 mol dm(-3)) ionic media by means of a potentiometric study. The distribution of arsenate species was defined depending on two important variables in natural environments: pH and composition. All the experimentation was performed at 25 degrees C. The differences found in the protonation constants for different medium compositions, were explained by the different behaviour of the interaction parameters of the species considered in the different media and ionic strengths. These parameters were reported for all hydrolitic As(V) species and were calculated using the Modified Bromley's Methodology (MBM). The corresponding thermodynamic stepwise formation constants were also determined (log degrees K(1)=11.58+/-0.01, log degrees K(2)=7.06+/-0.01, log degrees K(3)=2.25+/-0.01). All the results obtained showed not only the importance of the ionic strength but also of the composition of the ionic medium on the distribution of the acid-base species of As(V) as a function of pH in natural waters.

Optimisation of microwave-assisted extraction (MAE) for the extraction of polychlorinated biphenyls (PCBs) from soil samples has been accomplished using an experimental design approach. Variables studied have been: percentage of acetone (v/v) in an acetone:n-hexane mixture, solvent volume, extraction time, microwave power and pressure inside the extraction vessel. Five samples of a certified soil (CRM 481) have been extracted under the optimum conditions of the developed method and the results have been compared to those obtained by Soxhlet extraction. Good recoveries (>95%) have been obtained for all the PCBs studied. All extracts have been analysed by gas chromatography/mass spectrometry (GC/MS) and an optimum determination method for the electron impact mass spectrometric (EIMS) has also been developed.

A recently developed methodology for the determination of ion exchange equilibrium constants has been applied to ion exchange systems of 1:2 stoichiometry. Potentiometric titrations with variable ionic strength were carried out. Ionic medium titrations were performed for the estimation of the liquid junction potential. The modified Bromley's methodology and the Wilson model were used for the estimation of the activity coefficients of the species in the aqueous and resin phase, respectively. A modification of the Henderson equation is used for the estimation of liquid junction potentials in the mixtures including 1:2 electrolytes. Equilibrium constants for the H(+)/M(2+) (M=Mg, Ca, Sr and Ba) exchange systems in the strongly acidic resins Dowex CM-15 and Dowex C650 were studied.

The protolytic behavior of d-gluconic-delta-lactone acid has been studied by means of automated potentiometric titrations at different ionic strengths in the range 0.1

A new method for the determination of ion exchange equilibrium constants is developed. A technique based in the application of potentiometric titrations is used in the study of non selective strong acidic resins. Potentiometric titrations are carried out without constant ionic strength, so a mathematical treatment is developed in order to take into account the estimation of the activity coefficients and the liquid junction potentials. The ion exchange thermodynamic equilibrium constants for two resins, Dowex CM-15 and Dowex C650, between the proton form and the alkaline metals at 25 degrees C are given.

The protonation equilibrium of the Tris(Hydroxymethyl)aminomethane (TRIS) has been studied using an automated potentiometric system. The temperature was kept constant at 25 degrees C and the ionic strength was 0.1, 0.5, 1.0, 2.0 and 3.0 mol dm(-3) in NaClO(4). The experimental constants, obtained at different ionic strengths, were correlated by means of the modified Bromley methodology (MBM) and the thermodynamic protonation constant found to be log (0)beta = 8.07 +/- 0.01 . Those values together with some others for NaCl medium were used to construct a thermodynamic model on both molal and molar scales for the protonation equilibrium of TRIS.

A computer program called SPECA and written in compiled BASIC (Microsoft QuickBasic Ver. 4.5) has been written for the calculation of thermodynamic constants in solution equilibria studies from spectrophotometric measurements. In order to calculate the thermodynamic constants it is necessary to introduce different theories to estimate the activity coefficients of the system involved under investigation. In this version of the program the equations proposed in the models of Debye-Hückel. Specific Interaction Theory (SIT) or the Modified's Bromley Theory can be chosen. To achieve its purpose, the program uses absorbance and activity or free concentration data of one of the components, normally H(+), and it is not limited with respect to the number of components that can be studied. Minimization of the error square sum in the absorbance, which can be absolute or relative, is carried out using the Levenberg-Marquardt-Nash algorithm at three different levels: equilibrium constants in the first level, molar absorptivities in the second and interaction coefficients in the third for those systems using the SIT or the Modified Bromley's Theories.