Dolores Bellido-Milla

• Ph D
• Research Director at Universidad de Cádiz

In the present work, a novel and economical pH sensor has been improved through the application of the conducting polymers poly(3,4-ethylendioxythiphene) and poly(sodium 4-styrene sulphonate). Sinusoidal voltages were applied to electrodeposit the different polymers studied for different periods (10, 15, and 20 min) on the electrode surface. The pr...

A natural Moroccan illite-smectite clay was investigated as adsorbent of nickel in water. Before its use, it was processed without additives as honeycomb monoliths, an advantageous design in many methods developed to control environmental pollution. The performance of the resulting monoliths was studied in dynamic conditions by flow recirculation t...

In this work, a screening of Sonogel-Carbon (SNGC) electrodes modified with nanomaterials (carbon nanotubes and gold nanoparticles) and the study of their effect on the electrochemical performance of sinusoidal voltage (SV) and current (SC)-based biosensors are reported. Surface modification was achieved by drop-casting and electrodeposition method...

Natural illite–smectite and stevensite Moroccan clays were used for the simultaneous removal of lead and cadmium from aqueous medium. The clays were employed in raw state and extruded as honeycomb monoliths form without any additives, which confirms the novelty of this approach in water treatment. The experiments were done in batch conditions with...

A fast, precise and inexpensive alternative for evaluating the antioxidant activity (AA) in walnut kernel extracts is proposed. Traditional ABTS assay and an electrochemical index approach have been applied to evaluate the AA in walnuts. A fast and efficient defatting of the walnuts by ultrasound assisted extraction (UAE) was carried out. Later, fo...

In this work, template-free nanostructured conducting polymers (nCPs)-embedded gold nanoparticles (AuNPs) from aniline, thiophene and 3,4-ethylenedioxythiophene have been prepared via a one-pot sonochemical method. The synthesis of the nanocomposite (nCPs-AuNPs) was achieved in a short period of time (5–10 min), by applying high-energy ultrasound t...

This work is focused on the investigation of a composite material based on silver nanoparticles (AgNPs) and poly(3,4-ethylenedioxythiophene) (PEDOT) as sensing element of an electrochemical sensor for the determination of caffeic acid (CA). The novelties of the present work lie on the in-situ electrodeposition of AgNPs upon PEDOT layer using a sinu...

From the beginning of the Industrial Revolution in Great Britain back on the eighteenth century, and mainly from the enormous technological development in several fields (electronics, computing, and robotics) occurred on the second half of the twentieth century that affected deeply industrial processing and manufacturing, most part of society, and...

A very simple, sensible and advanced new methodology for the determination of copper species in seawater has been developed. The method consisted of two steps: first a separation/preconcentration of copper species by using liquid phase microextraction-based solvent bars followed by the direct analysis of these solid polymeric micro-samplers in an a...

In this work, a method for the determination of phosphorus in walnuts has been developed due to the fact that there is no specific method for this purpose. A closed-vessel microwave-assisted digestion of the samples was optimized and a modified molybdenum blue spectrophotometric method was carried out with excellent precision and selectivity. To di...

The synthesis of a new bulk material based on silicon oxide and poly-(3,4-ethylenedioxythiophene) (PEDOT), the Sonogel-Carbon-PEDOT material, is carried out. The main purpose is to obtain a bare conducting material, aided by statistical experimental design, able to be used as transducer for electrochemical devices. This new material tries also to s...

The application of a novel Poly(3,4-ethylenedioxythiophene)-Tyrosinase/Sonogel-Carbon electrode (PEDOT-Tyr/SNGC) biosensor to beers and wines analysis is proposed. This biosensor implies a new Sinusoidal Current (SC) electrodeposition method to immobilize the enzyme generating a nanostructure surface. The biosensors were characterized electrochemic...

Different natural Moroccan clays were used as adsorbents for the removal of lead from aqueous solution. The study was performed not only employing the starting clays in the form of powder but also after their extrusion as honeycomb monoliths, this representing the major novelty of this work respect to the current state-of-art. The experiments were...

Resumen Diferentes arcillas naturales del norte de Marruecos se utilizaron como adsorbentes para eliminar plomo de disoluciones acuosas. Este estudio se realizó no sólo empleando las arcillas de partida en forma de polvo sino también tras su extrusión para obtener monolitos en forma de panal de abeja. En el primer caso, los experimentos se realizar...

The direct analysis of solvent bars used for silver micro-extraction from seawater samples by high resolution continuum source solid sampling graphite furnace atomic absorption spectroscopy (HR-CS-SS-GF-AAS) has been achieved. Three successive pyrolysis steps at 290 ºC, 700 ºC and 1000 ºC were applied to ensure the elimination of the fumes released...

The direct analysis of solvent bars used for silver micro-extraction from seawater samples by high resolution continuum source solid sampling graphite furnace atomic absorption spectroscopy (HR-CS-SS-GF-AAS) has been achieved. Three successive pyrolysis steps at 290 ºC, 700 ºC and 1000 ºC were applied to ensure the elimination of the fumes released...

The direct analysis of solvent bars used for silver micro-extraction from seawater samples by high resolution continuum source solid sampling graphite furnace atomic absorption spectroscopy (HR-CS-SS-GF-AAS) has been achieved. Three successive pyrolysis steps at 290 �C, 700 �C and 1000 �C were applied to ensure the elimination of the fumes released...

In this work, biosensors based on Sonogel-Carbon electrodes modified with poly(3,4-ethylenedioxythiophene) – tyrosinase biocomposite materials have been developed using sinusoidal voltages and currents methods The sinusoidal voltages method uses a sinusoidal voltage signal of a 50 mHz fixed frequency and high amplitude superimposed on a direct curr...

The potential applicability of the continuum source solid sampling graphite furnace atomic absorption spectroscopy (CS SS-GF AAS) technique has been studied to carry out the direct analysis of microextraction solvent bars used for metal ultra-trace pre-concentration in natural waters. An optimisation of the temperature program was developed for thi...

In this paper, the sonocatalysis has been successfully used to synthesise silica nanoparticles. The Stöber method which implies silicon alkoxide, ammonia and aqueous alcohol solution with magnetic stirring followed by ultrasound bath was modified with the use of a high-power ultrasound probe. The factors considered to prepare silica nanoparticles w...

A critical review to the methods recommended by international bodies and widely used in the winery industry and research studies was performed. A Laccase biosensor was applied to the selective determination of polyphenols in wines. The biosensor response was characterised and it responds mainly to o-diphenols which are the principal polyphenols res...

Graphite powder-based electrodes have the electrochemical performance of quasi-noble metal electrodes with intrinsic advantages related to the possibility of modification to enhance selectivity and their easily renewable surface, with no need for hazardous acids or bases for their cleaning. In contrast with commercial electrodes, for example screen...

The traditional methods used to evaluate parameters related to beer ageing have been tested, revised and criticised. With this aim, a sampling of lager beers has been carried out. Sulphur dioxide, polyphenols and antioxidant capacity have been determined in fresh and aged beer. Only sulphur dioxide concentration showed relevant differences after th...

A third-generation biosensor based on HRP and a Sonogel–Carbon electrode has been fabricated with the aim of monitoring hydrogen peroxide in aqueous media via a direct electron transfer process. The redox activity of native HRP, typical of thin-layer electrochemistry, was observed. The charge coefficient transfer, α, and the heterogeneous electron...

Three phenoloxidases based biosensors were successfully developed using as electrochemical transducer a new type of electrode recently developed by our group: the "Sonogel-Carbon electrode". The employed enzymes were Trametes versicolor laccase (Lac), Mushroom tyrosinase (Tyr), and Horseradish peroxidase (HRP). Immobilization step was accomplished...

Beer contains certain components, which act as protective agents in relation to consumers ' health, such as antioxidants, which decrease over time. The shelf life of package beer is determined to a large extent by the appearance of haze or deterioration of the fl avor. A comprehensive understanding of the mechanisms involved in beer instability has...

The methodology most widely used to detect the antioxidant capacity (indirectly by ABTS+ discoloration) has been modified to be applied to beer samples due to signal instabilities. A new and direct method to follow beer ageing has been developed based on a simple organic solvent extraction follow by molecular absorption spectrophotometry UV–VIS (MA...

Many standard and official sample digestion procedures for trace metal determination are carried out in open vessels on hot plates. A new procedure for the determination of trace metals by flame atomic absorption spectrometry or inductively coupled plasmaatomic emission spectrometry in beer samples was developed to be performed in closed reactors a...

 A new sample treatment is proposed based on a partial wet digestion in closed reactors assisted by microwaves for wear metal determinations by flame atomic absorption spectrometry (FAAS). It is rapid, precise and sensitive and allows the use of inorganic standards. Problems concerning solubility have been overcome with mixed solvents. The repeatab...

Statistical multivariate techniques were applied to the metal content obtained from welder personal sampling at a shipyard. The data used were the concentration of Fe, Mn, Cu, Cr, Ni, Cd, Zn and the particle total content determined by AAS and by gravimetry. Predictive models for Fe and Mn concentrations have been obtained in function of the partic...

In this paper, a procedure for the simultaneous determination of three metallic ions in used marine lubricating oils by differential pulse anodic stripping voltammetry (DPASV) is proposed. Zn(II), Pb(II) and Cu(II) were the ions chosen as representative of specific marine engine wear. The DPASV was employed as an alternative to other analytical tec...

A new quartz crystal microbalance sensor is developed to determine formic acid at low concentrations. Four previously selected polymers with acid-base characteristics were tested as possible coatings. Polyoxyethylene bis [amine] presented the best results. The sensor is rapid, sensitive [0.67 Hz/(mg/m3)], and reversible at low concentrations. The d...

The characterization of beer samples has a lot of interest because their composition can affect the taste and stability of beer and consumer health. Flame atomic absorption spectrometry was used to determine Fe, Mn, Zn, Cu, Mg, Ca and Al. Sodium and K were determined by flame atomic emission spectrometry. A sample preparation method was developed,...

The determination of wear metals and metalloids in used lubricating oils allows the prediction of equipment failure. A number of procedures to determine wear metals in lubricating oils by atomic spectrometry has been published. Industry has lately shown a special interest in the determination of tin, since its appearance at certain levels in used o...

 The difficulties associated with the development of a microwave-assisted acid digestion of lubricating oils in determination of wear metals are presented. The interest of this sample treatment lies in its basis for determining the total metal contents with enough sensitivity by flame atomic absorption spectrometry (FAAS). It allows earlier diagnos...

The conditions in a shipyard that could affect the metal content in welding fumes were studied. Personal samples were collected on cellulose filters in compliance with standard methods. The total metallic particles content was determined by gravimetry. The filters were then dissolved by acid digestion and the metals (Fe, Mn, Zn, Cu, Cr, Ni and Cd)...

The metal contents of welding fumes produced at the shipyard Astilleros Españoles in Puerto Real, Spain, were investigated to assess the hygiene hazards in order to improve health conditions at the factory. Personal and environmental samples were collected on a cellulose or polyvinylchloride filter with the aid of a sampler in compliance with Natio...