Eduardo Paredes

• PhD
• PostDoc Position at University of Barcelona

The Early-Middle Pleistocene Transition (EMPT), a global climate event that occurred between 700-1250 thousand years (kyr) ago, was characterized by a drastic change in the deep thermohaline circulation, resulting in more intense and longer-lasting interglacial periods. High-resolution records documenting environmental changes on the ocean seafloor...

The Antarctic Circumpolar Current plays a pivotal role in global climate through its strong influence on the global overturning circulation, ocean heat and CO2 uptake. However, when and how the Antarctic Circumpolar Current reached its modern-like characteristics remains disputed. Here we present neodymium isotope and sortable silt records from sed...

Eastern Mediterranean deep-intermediate convection was highly sensitive to varying inputs of fresh water fluxes associated with increased rainfall during the African Humid period (15-6 kyr Before Present). Here we investigate changes in the water-outflow from the Eastern Mediterranean Sea since the last deglaciation using neodymium isotope ratios....

Uranium exposure can lead to neurobehavioral alterations in particular of the monoaminergic system, even at non-cytotoxic concentrations. However, the mechanisms of uranium neurotoxicity after non-cytotoxic exposure are still poorly understood. In particular, imaging uranium in neurons at low intracellular concentration is still very challenging. W...

Actinide elements, all radioactive, are present on Earth for a period several orders of magnitude longer than the life cycle of a human being. Their toxicology is therefore a societal issue, even in the absence of accidental nuclear events. Since the first studies conducted during World War II, actinide toxicologists have studied their retention an...

Uranium exposure can lead to neurobehavioral alterations in particular of the monoaminergic system, even at non-cytotoxic concentrations. However, the mechanisms of uranium neurotoxicity after non-cytotoxic exposure are still poorly understood. In particular, imaging uranium in neurons at low intracellular concentration is still very challenging. W...

Seawater rare earth element (REE) concentrations and Nd isotopic composition (εNd) are increasingly applied as valuable tracers of oceanographic processes such as water mass mixing and lithogenic inputs to seawater. However, their measurements are basically lacking in the Mediterranean Sea water column. This study analyzes 9 seawater stations aroun...

The study of isotopic variations of endogenous and toxic metals in fluids and tissues is a recent research topic with an outstanding potential in biomedical and toxicological investigations. Most of the analyses have been performed so far in bulk samples, which can make the interpretation of results entangled, since different sources of stress or t...

Uranium (U) is the heaviest naturally occurring element ubiquitously present in the Earth’s crust. Human exposure to low levels of U is, therefore, unavoidable. Recently, several studies have clearly pointed out that the brain is a sensitive target for U, but the mechanisms leading to the observed neurological alterations are not fully known. To de...

Abstract The impact of natural uranium (U) on differentiated human neuron-like cells exposed to 1, 10, 125, and 250 µM of U for seven days was assessed. In particular, the effect of the U uptake on the homeostatic modulation of several endogenous elements (Mg, P, Mn, Fe, Zn, and Cu), the U isotopic fractionation upon its incorporation by the cells...

Natural uranium is an ubiquitous element present in the environment and human exposure to low levels of uranium is unavoidable. Although the main target of acute uranium toxicity is the kidney, some concerns have been recently raised about neurological effects of chronic exposure to low levels of uranium. Only very few studies have addressed the mo...

The monitoring of isotopic fractionations in in vitro cultured human cell samples is a very promising and under-exploited tool to help identify the metabolic processes leading to disease-induced isotopic fractionations or decipher metabolic pathways of toxic metals in these samples. One of the limitations is that the analytes are often present at s...

Significance In vivo isotopic fractionation studies of metals in living organisms have recently revealed an outstanding potential for biomedical and toxicological studies. In vitro studies in cellular models are underexploited, although they have the potential to provide invaluable information to understand the processes at the origin of such isoto...

Data most commonly used at present to calibrate measurements of mercury vapor concentrations in air come from a relationship known as the “Dumarey equation”. It uses a fitting relationship to experimental results obtained nearly 30 years ago. The way these results relate to the international system of units (SI) is not known. This has caused diffic...

It is shown how ratios of element mass fractions could possibly be used as markers for origin determination of biodiesel materials of the 1st generation. This is a feasibility study on three samples of soya beans, three samples of canola/rape seeds and the six corresponding final biodiesel products. It is underpinned by a careful validation of the...

Preliminary investigations have shown that performing Sr isotope ratio measurements at 15 μL min−1 (continuous flow, for 300 μL large samples) by multi-collector Inductively Coupled Plasma Mass Spectrometry using a heated torch integrated spray chamber (TISIS) was possible at the same level of uncertainty as for measurements at 200 μL min−1 (using...

The need for performing isotope ratio measurements by MC-ICPMS on samples only available in small sizes and not allowing any dilution requires the development of sample introduction systems that can run below 10 μL min−1 sample flow rate (continuous mode). With a torch integrated sample introduction system (TISIS), optimisation of the running condi...

In this work, a new extraction method termed aerosol phase extraction has been developed for the first time. The new method was based on the nebulisation of the sample onto the extracting solution to maximize the contact surface. The influential parameters are: agitation time, chelating agent concentration and inorganic acid concentration. The meth...

In the present work, an evaporative light scattering detector was used as a high-temperature liquid chromatography detector for the determination of carbohydrates. The compounds studied were glucose, fructose, galactose, sucrose, maltose, and lactose. The effect of column temperature on the retention times and detectability of these compounds was i...

We propose a method for the authentication of the origin of vegetables grown under similar weather conditions, in sites less than 10 km distance from the sea and distributed over a rather small scale area (58651 km2). We studied how the strontium (Sr) isotopic signature and selected elemental concentrations ([Mn], [Cu], [Zn], [Rb], [Sr] and [Cd]) i...

The capabilities of inductively coupled plasma atomic emission spectrometry (ICP-AES) for the determination of water-soluble vitamins after high-performance liquid chromatography (HPLC) separation have been evaluated for the first time in the present work. Thanks to the multielemental capability of ICP-AES, it has been possible to develop a method...

This study characterises for the first time isotope ratio measurements by multi-collector ICPMS when performed at liquid flow rates as low as 10–15 µL min−1. An evolution of the torch integrated sample introduction system (TISIS) was employed, which combined an OpalMist nebulizer and a heated single pass spray chamber, allowing the transport of alm...

In the present work, an inductively coupled plasma atomic emission spectrometry (ICP-AES) system was used as a high temperature liquid chromatography (HTLC) detector for the determination of alcohols and metals in beverages. For the sake of comparison, a refractive index (RI) detector was also employed for the first time to detect alcohols with HTL...

The characteristics of the aerosols generated by pneumatic concentric nebulizers as well as sensitivities were studied in ICP-MS with a total of 26 nebulizers: 17 of the A-type, 6 of the C-type, and 3 of the K-type. Although of the same design, discrepancies in sensitivity were observed among the A1-30 type nebulizers. Free delivery rate, relation...

The coupling of a High-Temperature Liquid Chromatography system (HTLC) with an Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) is reported for the first time. This hyphenation combines the separation efficiency of HTLC with the detection power of a simultaneous ICP-AES system and allows the combined determination of organic compou...

Synopsis A simple method for the simultaneous determination of a cationic surfactant (cetrimonium chloride) and four non‐ionic surfactants (1‐tetradecanol, 1‐hexadecanol, 1‐octadecanol and 1‐eicosanol) has been developed. Direct extraction of the analytes from the sample with methanol and a subsequent separation using reversed‐phase high‐performanc...

A systematic study about the effect of the heating of a modified version of the so-called Torch Integrated Sample Introduction System (TISIS) has been performed. The results showed that when working at liquid flow rates of 20–40 µl min−1, it was possible to raise the chamber wall temperature up to 100 °C without degradation of plasma thermal charac...

A HPLC-inductively coupled plasma atomic emission spectrometer (ICP-AES) hyphenation technique was used to determine the concentration of some organic (i.e., carbohydrates, carboxylic acids) as well as inorganic (metals and anions) compounds in tomato samples. A high efficiency nebulizer (HEN) coupled to a low inner volume cyclonic spray chamber (C...

Interfering effects caused by inorganic matrices (inorganic acids as well as easily ionized elements) in inductively coupled plasma-atomic emission spectroscopy have been modeled by regression analysis of experimental data obtained using the “stirred tank method”. The main components of the experimental set-up were a magnetically-stirred container...

A new calibration method for high-performance liquid chromatography was validated. The method was called single-injection calibration approach (SICA) because it allowed to obtain a complete calibration curve by means of a single injection of a standard solution containing several non-volatile and semi-volatile organic compounds at different concent...

The applicability of the HPLC-ICP-AES coupling for the simultaneous determination of carbohydrates, carboxylic acids, alcohols, and metals in a single chromatographic run has been demonstrated in the present work. Five saccharides, glucose, fructose, sucrose, sorbitol, and lactose; five carboxylic acids, citric, tartaric, malic, lactic, and acetic;...

A stirred tank was used for the first time to elucidate the mechanism responsible for inductively coupled plasma atomic emission spectroscopy (ICP-AES) matrix effects caused by inorganic, acids and easily ionized elements (EIEs), as well as organic, ethanol and acetic acid, compounds. In order to gradually increase the matrix concentration, a matri...

A new calibration method was developed and applied to inductively coupled plasma atomic emission spectrometry. External calibration was performed as follows. A container was filled with a given volume of deionized (V p) water. Then a concentrated standard was introduced at a controlled rate (Q e) into the tank by means of a peristaltic pump. The re...

Póster presentado en European Winter Conference on Plasma Spectrochemistry 2007, 18-23 February 2007, Taormina, Italy The determination of carbohydrates, carboxylic acids and metals is a subject of great interest in the field of food science because their presence and concentration can influence on food quality. Besides the study of the profiles of...

Comunicación presentada en la VI Reunión Científica de la Sociedad Española de Cromatografía y Técnicas Afines, Vigo, 8-10 noviembre 2006