Sofia Capelo

Application of Chemometrics in Separation Science

Abstract Chemometrics aims at extracting maximum information through the application of statistics and mathematics to problems of a chemical nature. Over the years, chemometrics has become an important chemical discipline with a significant impact in analytical chemistry, including the incorporation of significant improvements in design and selection of optimal experimental procedures, calibration of analytical instrumentation, and advanced methods for analysis of chemical data. The application of chemometrics methods to separation science, mainly chromatography and capillary electrophoresis, has followed the same increasing trend as in any other field of analytical chemistry. However, reviews on the application of chemometrics in separation science have been very scarce. Therefore, in this paper, the development of chemometrics in chromatography and capillary electrophoresis will be presented with a view of the current state of the‐art and with the prospects for the future.

Dating Archaeological Copper/Bronze Artifacts by Using the Voltammetry of Microparticles

A method for dating copper/bronze archaeological objects aged in atmospheric environments is proposed based on the specific signals for cuprite and tenorite corrosion products measured through the voltammtry of microparticles method. The tenorite/cuprite ratio increased with the corrosion time and fitted to a potential law that yielded a calibration curve usable for dating purposes.

In situ continuous monitoring of chloride, nitrate and ammonium in a temporary stream Comparison with standard methods

A multi-parameter probe was used for in situ chloride, nitrate and ammonium measurements in a temporary stream (Ribeira da Pardiela, in the South of Portugal). Comparison with standard analytical methods was performed for all elements. For chloride, the results of the probe depicted the same behaviour as that obtained with the standard method, although it is clear that the matrix effects were present. For nitrate, the results obtained with the probe were in agreement with the other standard methods used, except for samples collected during drought, when the stream water became brownish and exhaled an offensive smell, due to the decomposition of organic matter. For ammonium, surprisingly the probe show to be the best option, the phenate method being affected by matrix effects. The results still suggest an interference of the bicarbonate ion on nitrate determination, but standard additions approach was shown to minimize most of the matrix effects. Recoveries were reasonable to good for all the three anions under scrutiny.

Kinetics of dissociation of copper(II)-proline complex by cyclic voltammetry with a Nafion®-coated electrode

Abstract The kinetics of dissociation of copper(II)-proline complexes were studied by cyclic voltammetry using two types of electrode: a hanging mercury drop and a Nafion®-coated thin mercury film. In the former case and depending on the free ligand concentration, quasi-labile behaviour and labile behaviour were observed for identical time scales of the technique used. This was attributed to the adsorption of the negatively charged free ligand on the mercury aqueous solution interface in the potential region where Cu(II) reduction occurs, subsequently inducing the adsorption of the metal ion. The use of the Nafion-modified electrode, i.e. the latter case, seemed to avoid interferences effectively due to adsorption of negatively charged compounds. Kinetic data obtained via cyclic voltammetry are in good agreement with the literature values obtained by spectroscopic techniques.

Effect of lead on the uptake of nutrients by unicellular algae

Abstract From batch growth experiments carried out with the alga Selenastrum capricornutum Printz the evolution of uptake of nitrogen and phosphorus with time in the absence and presence of lead 1 × 10−6 M and at pH 7 and 4 has been considered. The change of pigments (chlorophylls a, b and vegetal carotenoids) with time, as well as the labile and total lead in the medium and in the alga and the fluorescence compounds released by the alga, have also been analysed. Relationships between phosphorus in the alga and the pigments and lead in the cell, as well as between phosphorus and fluorescence compounds exudated by each unit of the unicellular alga, have been examined in order to try to understand the biochemical mechanism.

Why are Cultural Landscapes of Various Values? Thinking About Heritage Landscape Evaluation and Monitoring Tools

Why are Cultural Landscapes of Various Values? Thinking About Heritage Landscape Evaluation and Monitoring Tools The aim of this paper is to contribute towards the successful management of heritage landscapes. Many cultural landscapes represent high heritage value and should be classified as heritage landscapes; therefore, special tools should be considered to be used in managing them. These landscapes should be evaluated according to heritage science criteria and good practice guidelines should be established. Several useful heritage landscape evaluation criteria were identified and characterised, and their relative importance was analysed, enabling the establishment of a heritage value hierarchy by means of a weighted linear combination. This is significant in the context of land management measures for countryside valorization promoting rural development. However, this approach also requires awareness of the link between the present cultural landscape and the history of the people that have interacted with the area involved. This is also important for the establishment of a priority ranking system for monitoring criteria indicators. A method for doing this is also proposed by the authors.