Sagrario García Martín

A procedure based on magnetic solid-phase extraction followed by capillary electrophoresis (CE) has been developed for the determination of Zn, Cu, Mn and Cd in grape marc spirit samples. Two different sorbents, carboxylic group functionalized silica nanoparticles (Si-COOH-NPs) and multi-walled carbon nanotubes (MWCNTs), were compared. Separation and quantification of the metals by CE were performed after their complexation with phenanthroline. The optimization of variables affecting the extraction procedure was carried out to achieve the best extraction efficiency. Both sorbents yielded quantitative (recoveries in the ranges of 98–102 and 79–92% for Si-COOH-NPs and MWCNTs, respectively), precise (RSD < 7.5%), sensitive (LODs between 0.5–2.2 and 5–9 μg/L for Si-COOH-NPs and MWCNTs, respectively) results with linearity over one order of magnitude. The application of both sorbents for the extraction of metals from grape marc spirit samples with European protected geographical indication Orujo de Galicia showed that carboxylic functionalized silica particles provided the best results. However, MWCNTs remain an attractive alternative sorbent.

Honeybees interact strongly with vegetables, air, soil, and water in the vicinity of the hive and, as a consequence, pollutants from these sources are translated to the honeybees and to the hive products. Therefore, over the last decades of the past century, honeybees and honey have been proposed as possible bioindicators for the study of the environmental status of the area surrounding the hive. This work is a critical review on the use of the hive as a passive sampling device and on the use of honeybees and honey as environmental bioindicator substrates for metals and radionuclides. The design of sampling networks, sampling procedures, sample pretreatments, analytical techniques, data analysis, and other influencing factors in this area are also reviewed.

New materials have significant impact on development of new methods and instrumentation for chemical analysis. From the discovery of carbon nanotubes in 1991, single and multi-walled carbon nanotubes (SWCNTs and MWCNTs) -due to their high adsorption and desorption capacities- have been employed as sorption substrates in solid-phase extraction for the preconcentration of heavy metals from diverse matrices. In the present work, a new method for the Pb determination by electrothermal atomic absorption spectrometry (ETAAS) in urine at low levels has been developed. Lead was separated from the undesirable urine matrix by means of a solid phase extraction (SPE) procedure using oxidized multiwalled carbon nanotubes as a sorbent material.