Los procesos químicos como factores de alteración de materiales pétreos empleados en construcción

Desde hace ya unos años, existe un interés creciente por los procesos de deterioro que están sufriendo una gran parte de los monumentos, y fundamentalmente aquellos construidos en piedra. Ha de aclararse, en primer lugar, que el proceso de deterioro es algo inherente a las características intrínsecas de los materiales empleados. En el caso de la piedra, desde que es extraída de la cantera comienza a sufrir una serie de procesos físicos, químicos y fisicoquímicos a fin de alcanzar unas nuevas condiciones de equilibrio con el nuevo medio circundante. Los procesos que tengan lugar en la piedra dependerán, en condiciones normales del microclima del entorno más inmediato así como de los esfuerzos a los que se vea sometida como parte del conjunto arquitectónico; de esta forma, un mismo material puede tener, a lo largo del tiempo, un comportamiento muy diferente dependiendo de su ubicación definitiva, tanto geográfica como de uso. No obstante, la velocidad con que actúan estos procesos degradativos normales es generalmente muy baja, al menos en sus etapas iniciales, por lo que cabría esperar una mayor durabilidad en muchos materiales pétreos que actualmente se encuentran en un muy avanzado estado de alteración. lementos ornamentales realizados en piedra ha puesto de manifiesto que hasta principios de este siglo, el deterioro producido era ciertamente el que cabía esperar de acuerdo con las características de los materiales, condiciones ambientales, esfuerzos y tiempo desde su puesta en obra; sin embargo, es a partir de este momento cuando se comienza a apreciar una aceleración creciente en los procesos degradativos, mucho más acusada ya en nuestros días, que no puede explicarse en base al incremento paulatino que se produce en la velocidad de todo proceso de alteración. Ciertamente, el entorno más inmediato a los monumentos ha ido sufriendo, en general, serias transformaciones en lo que respecta a urbanismo, por ejemplo en el incremento de altura en las edificaciones y, lo que es más importante, en el aumento en las concentraciones de ciertos contaminantes atmosféricos con posibles efectos, tanto primarios como secundarios, sobre la integridad de los materiales pétreos y que son el origen de diversos procesos químicos de alteración denominados genéricamente procesos de corrosión. Conviene señalar, asimismo, que la alteración en un monumento particular depende de un cúmulo de factores tanto intrínsecos como extrínsecos al material o materiales empleados, por lo que aunque se pueden aplicar ciertas generalizaciones, para poder explicar la diversidad y grado de alteración de un monumento se debe realizar un estudio exhaustivo en el que se considere toda la problemática particular del edificio en cuestión, así como todos los ensayos necesarios para establecer el tipo o tipos y grado de alteración presentes

Determination of phosphorous oxoanions in pharmaceuticals using non- suppressed ion chromatography

The separation and quantitation of phosphorous oxoanions have been investigated by non-suppressed ion chromatogra- phy (IC) with conductometric detection using a modified gluconate-borate buffer as eluent. Hypophosphite being coeluted with the injection peak, its previous oxidation into phosphate is necessary. The method was applied to the determination of hypophos- phite and phosphate in several pharmaceutical

Quick Analysis of Organic Amendments via Portable X-ray Fluorescence Spectrometry

The determination of heavy metals in soils and organic amendments, such as compost, manure, biofertilizer, and sludge, generally involves the digestion of samples with aqua regia, and the determination of those in the solution using various techniques. Portable X-ray fluorescence (PXRF) has many advantages in relation to traditional analytical techniques. However, PXRF determines the total elemental content and, until now, its use for the analysis of organic amendments has been limited. The objective of this work is the calibration of a PXRF instrument to determine the aqua regia-soluble elemental contents directly in solid samples of organic amendments. Our proposal will avoid the digestion step and the use of other laboratory techniques. Using a training set of samples, calibration functions were obtained that allow the determination of the aqua regia-soluble contents from the PXRF readings of total contents. The calibration functions (obtained by multiple linear regression) allowed the quantitative determination of the aqua regia-soluble contents of Fe, K, P, S, Zn, Cu, Pb, Sr, Cr, and Mn, as well as the organic matter content and a semi-quantitative assessment of Al, Ca, V, Ba, Ni, and As contents. The readings of Si, Fe, Al, Ca, K, or S were used as correction factors, indicating that the calibrations functions found are truly based on the chemical composition of the sample matrix. This study will allow a fast, cheap, and reliable field analysis of organic amendments and of other biomass-based materials.Spanish Ministry of Science, Innovation and Universities, and the European Regional Development Fund, European Union, (AEI/FEDER, UE), grant number CGL2016-78937-R

Alteration mechanisms on the stones of the Cathedral of Granada (Spain)

Español: Se analizan los diversos mecanismos de alteración que actúan sobre los materiales pétreos usados en la Catedral de Granada. Se estudia con detalle la acción del agua, influencia antropogénica, oscilaciones térmicas, factores de incompatibilidad, movimientos sísmicos y factores de tipo biológico. Inglés: Alteration mechanisms on the stones of the Catedral of Granada, Spai

Chitosan tailor-made membranes as biopolymeric support for electromembrane extraction

El período de embargo ha expirado ya al ser del año 2019A chitosan membrane composed by 60% (w/w) chitosan and 40% (w/w) Aliquat®336 has been proposed as a new biopolymeric support for electromembrane extraction. The new support has been characterized by Scanning Electron Microscopy, resulting a 30–35 µm thickness. Amoxicillin, nicotinic acid, hippuric acid, salicylic acid, anthranilic acid, ketoprofen, naproxen and ibuprofen have been successfully extracted using the proposed support. Better enrichment factors were obtained for the acidic polar analytes than for the non-steroidal anti-inflammatory compounds (ranging from 118 for hippuric acid and 20 for ibuprofen). Electromembrane extraction was developed applying a DC voltage of 100 V, 1-octanol as supported liquid membrane and 20 min of extraction. The target analytes have also been satisfactorily extracted from human urine samples, providing high extraction efficiencies. The chitosan membrane is presented as a promising alternative for supporting liquid membrane compared to commonly used materials for this purpose.Ministerio de Educación y Ciencia (MEC). España CTM2015–67902-C-1-

Uptake Study in Juncus sp. and Salicornia Europaea of Six Pharmaceuticals by Liquid Chromatography Quadrupole Time-of-flight Mass Spectrometry

In this work, eight plants of Juncus sp. and ten of Salicornia europaea were used for an uptake assay of pharmaceuticals (flumequine, cirpofloxacin, enrofloxacin, carbamazepine, diclofenac and ibuprofen) by irrigation at three concentration levels: 10 ng mL−1 (low level); 700 ng mL−1 (medium level) and 10 μg mL−1 (high level). Two plants irrigated with pharmaceutical-free water were set up as controls. For each level, two plants were watered every day with 50 mL (Juncus sp.) and every two days with 20 mL (Salicornia europaea) of aqueous solutions containing all the analytes at the described concentrations. Plants irrigated at 10 μg mL−1 were significantly the most affected, whereas the rest of the plants remained, in general, largely displayed no apparent physiological effects throughout the 30 days (Juncus sp.) and 21 days (Salicornia europaea) assays. Leaves and stems were cut every seven days and roots were collected at the end of the assay. The samples were lyophilized, submitted to a microwave assisted extraction using 5 mL of acetonitrile:water mixture (1:1, v/v) and they were analyzed (in triplicate) in a liquid chromatography-quadrupole time of flight mass spectrometry instrument. Most of the analytes were quantified in many of the samples corresponding to the three exposure levels with the highest concentrations obtained at high exposure levels. Ibuprofen was not detected in any sample and enrofloxacin, ciprofloxacin and diclofenac were not detected in the samples from Salicornia europaea.Ministerio de Economía y Competitividad CTM2015-67902-C-1-PMinisterio de Ciencia e Innovación PGC2018-096608-B-C2

Morfología macroscópica de alteración de la piedra del conjunto catedralicio de Granada/España

Los principales factores de alteración que actúan en el conjunto catedralicio de Granada son, uno natural de origen térmico, dadas las bajas temperaturas que se alcanzan en invierno, y las grandes oscilaciones térmicas que se registran durante gran parte del año, y los de origen antropogénico, fundamentalmente los de mal uso de elementos de sujeción metálicos oxidables y los de contaminación atmosférica debida a productos de combustión. De esta forma, los mecanismos de alteración primordiales son los de heladicidad por la expansión producida por la congelación del agua retenida en los poros y microgrietas, sobre todo en los elementos arquitectónicos de mayor superficie de exposición y en su orientación umbría. Los indicadores a que ello conduce son las fisuras y fragmentaciones. Así, muchos elementos de piedra de Santa Pudia de la crestería de la Capilla Real se han perdido y los que quedan se encuentran muy degradados. La piedra de Sierra Elvira de las cornisas, más compacta, también se ve afectada por este mecanismo, iniciado por las microgrietas provocadas por dilataciones diferenciales debidas a oscilaciones térmicas, que facilitaron el acceso al agua. La expansión de hierros al oxidarse ha provocado la fracturación y fisuración de gran número de elementos ornamentales como bolas, pináculos, etc, que han obligado al desmontaje de muchos de ellos por el riesgo de caída, sobre todo en las terrazas superiores del monumento. Los mecanismos de disolución, ciclos de cristalización y acción química han conducido a la pérdida abundante de materia, tanto en forma de arenizaciones, sobre todo en las zonas de mayor humedad, como de formación de huecos (picados, alveolizaciones, estriados), en aquellas zonas más expuesta al viento. Esto afecta de forma generalizada a las zonas bajas en todo el perímetro del edificio, excepto en gran parte de la fachada principal, así como en todos los antepechos y en las superficies situadas debajo de las cornisas. Estas arenizaciones se ven favorecidas cuando existen placas biológicas o depósitos de inquemados, siendo estos últimos de mayor abundancia en las superficies más cercanas a la Gran Vía y en su orientación hacia ésta. Por último, y sobre todo por su repercusión estética, es necesario mencionar los abundantes depósitos de guano de palomino, cuya mayor presencia se da en la fachada principal.The main factors of deterioration that affect the Cathedral Whole of Granada are one of natural thermic origin due to the low temperatures during the winters and the higher thermic oscillations and those of anthropogenical origin: fundamentally the oxidation of metallic elements and atmospheric pollution due to burnt products. For this reason, the more important deterioration mechanisms arethe freezing ones due to the expansión produced in the v^ater retained inside the pores and microcracks, fundamentally in the architectonic elements with high expositional surface and in their shady orientation; the main indicators produced are fissuring and spalling. In this way, a lot of elements of Santa Pudia stone located in the Royal Chapel crenellations have disappeared and the rest are very deteriorated. The more compact Sierra Elvira stone used on the upper zone of the cornices has also been affected by the freezing mechanism, which starts with the microcracks produced by differential dilatations due to the thermic oscillations which made the water access easy. The iron corrosión and later expansión of the oxidation products has provoked the cracking and fissuring of many ornamental elements like balls, pinnacles, etc, and this situation has obliged their dismantling on the upper zones due to the danger to the public. The mechanisms of dissotution, crystallization cycles and Chemical action have led to abundant material loosening in the form of grain disgregation overcoats on the higher humidity zones, and formation of hollows (pitting, alveolar erosión, striations) in the zones more exposed to the winds. This situation is generalized in the lower zones of the monument, except on the main fagade, and in the parapets and lower zones of the cornices. The grain disgregations are more important when biological crusts or unburned deposits exist, the latter being of major abundance on the surfaces near the Gran Vía and in its orientation. It is necessary to mention the pigeon dung deposits, very important in the main fagade, with greater stetical repercussion

A comprehensive study of a new versatile microchip device based liquid phase microextraction for stopped-flow and double-flow conditions

A new geometry for a versatile microfluidic-chip device based liquid phase microextraction was developed in order to enhance the preconcentration in microfluidic chips and also to enable double-flow and stopped-flow working modes. The microchip device was combined with a HPLC procedure for the simultaneous determination of two different families as model analytes, which were parabens and non-steroidal anti-inflammatories (NSAIDs): Ethyl 4-hydroxybenzoate (Et-P), Propyl 4-hydroxybenzoate (Pr-P), Butyl 4-hydroxybenzoate (Bu-P), IsoButyl 4-hydroxybenzoate (iBu-P), salycilic acid (SAC), ketoprofen (KET), naproxen (NAX), diclofenac (DIC) and ibuprofen (IBU) in urine samples. The new miniaturized microchip proposed in this work allows not only the possibility of working in double-flow conditions, but also under stagnant conditions (stopped-flow) (SF-μLPME). The sample (pH 1.5) was delivered to the SF-μLPME at 20 μL min−1 while keeping the acceptor phase (pH 11.75) under stagnant conditions during 20 min. The highest enrichment factors (between 16 and 47) were obtained under stopped-flow conditions at 20 μL min−1 (sample flow rate) after 20 min extraction; whereas the extraction efficiencies were within the range of 27–81% for all compounds. The procedure provided very low detection limits between 0.7 and 8.5 μg L−1 with a sample volume consumption of 400 μL. Parabens and NSAIDs have successfully been extracted from urine samples with excellent clean up and recoveries over 90% for all compounds. In parallel, the new device was also tested under double flow conditions, obtaining good but lower enrichment factors (between 9 and 20) and higher extraction efficiencies (between 45 and 95) after 7 min extraction, consuming a volume sample of 140 μL. The versatile device offered very high extraction efficiencies and good enrichment factor for double flow and stopped-flow conditions, respectively. In addition, this new miniaturized SF-μLPME device significantly reduced costs compared to the existing analytical techniques for sample preparation since this microchip require few microliters of sample and reagents and it is reusabl

Use of Polymer Inclusion Membranes (PIMs) as Support for Electromembrane Extraction of Non-steroidal Anti-inflammatory Drugs and Highly Polar Acidic Drugs

The use of polymer inclusion membranes (PIMs) as support of 1-octanol liquid membrane in electromembrane extraction (EME) procedure is proposed. Synthesis of PIMs were optimized to a composition of 29% (w/w) of cellulose triacetate as base polymer and 71% (w/w) of Aliquat®336 as cationic carrier. Flat PIMs of 25 µm thickness and 6 mm diameter were used. EME protocol was implemented for the simultaneous extraction of four non-steroidal anti-inflammatory drugs (NSAIDs) (salicylic acid, ketoprofen, naproxen and ibuprofen) and four highly polar acidic drugs (anthranilic acid, nicotinic acid, amoxicillin and hippuric acid). Posterior HPLC separation of the extracted analytes was developed with diode array detection. Recoveries in the 81–34% range were obtained. EME procedure was applied to human urine samples.Ministerio de Educación y Ciencia TM2015-67902-C-1-PPremio Mensual Publicación Científica Destacada de la US. Facultad de Químic