Mercury pollution assessment in soils affected by industrial emissions using miniaturized ultrasonic probe extraction and ICP-MS

A combination of probe ultrasonic extraction, optimized by surface response methodology, and Inductively coupled plasma mass spectrometry (ICP-MS) detection is described in this work as an effective methodology  for mercury monitoring in soils affected by industrial emissions. Minute amounts of samples (typically
20 mg) can be extracted in 3 min by 1 mL of HCl-based extracting solution, without risk of mercury losses, and sub sequentially assayed by ICP-MS. The method was successfully tested on soil standard reference materials and then applied to mercury monitoring in a large set of real soil samples collected during a long-term monitoring survey (2007–2011) around the industrial area of Puchuncaví, Chile. The method proved to be useful for investigation of spatial and temporal mercury variability in the area, showing an intermediate to high mercury contamination with potential impact on the surrounding ecosystem. Published in the International Journal of Environmental Science and Technology.  Read more

Wearable electrochemical sensors: innovative tools for the emerging mobile health ecosystem

Wearable electrochemical sensors: innovative tools for the emerging mobile health ecosystem, Journal of Applied Bioanalysis 1(3) (2015) 68-71. With an estimated present global market of US$ 86.3 billion and expected annual increase around 7.9 % from now to 2020, sensors are nowadays one of the most active areas of research and technological developments [1] and a basic pillar of the emerging mobile health strategy that is expected to be revolutionizing healthcare in the near future. The biosensor and chemical sensor category is one of the most growing segment of this market, mainly due to increased use for medical purposes. Wearable electrochemical sensors conform a particularly flourishing category that benefits from the improvements in micro and nano fabrication of electrodes and instrumental components based on a range of new electrode materials (e.g. graphene). They are also expanding thanks to the widespread availability of advanced signal processing and management technologies on smartphones, tablets and similar portable devices. The aim of this contribution is to highlight the most outstanding recent progresses in the field of wearable electrochemical sensors for decentralized bioanalysis and show some examples of research trends that will shape the sector and expand applicability fields in the near future.

Long-term assessment of ecological risk from deposition of elemental pollutants in the vicinity of the industrial area of Puchuncavi-Ventanas, central Chile

Long-term assessment of ecological risk from deposition of elemental pollutants in the vicinity of the industrial area of Puchuncavi-Ventanas, central Chile: Science of The Total Environment, Volume(s) 527-528, 14-May-2015, Pages 335-343. The present work investigates soil pollution by elemental contaminants and compares ecological risk indexes related to industrial activities for the case study of Puchuncaví-Ventanas: a relevant industrial zone located in central Chile. Selected elements (As, Pb, Cd, Ni, Hg, V, Mn, Zn, Sr, Sb, Cr, Co, Cu, K, and Ba) were analyzed during a long-term period (yearly sampling campaigns during 2007–2011), at 5 sampling stations representing different degrees of impact. PCA and cluster analysis allowed identifying a copper smelter and a coal-fired power plant complex asmajor pollution sources. Geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (Cf), contamination degree (Cdeg), and integrated pollution index (IPI) are critically discussed for quantitative ecological risk assessment. Igeo, EF and Cf indexes are producing comparable environmental information, showing moderate to high pollution risks in the area that demands further monitoring and adoption of prevention and remediation measures.

Quality assurance in aerosol analysis

The journal Accreditation and Quality Assurancew has recently published our paper "Method validation and quality assurance of an ICP-MS protocol for the evaluation of trace and major elements in ambient aerosol samples and application to an air quality surveillance network". This study presents the results of a quality assurance evaluation program applied to the method routinely used for the evaluation of a large elemental profile in aerosol samples from the air quality surveillance network of Extremadura, Spain, where low pollution levels are usually encountered. A critical evaluation of the most relevant analytical steps is presented, including long-term blank values evaluation, limits of detection, certified reference material recoveries, method uncertainty and results of comparison studies for gravimetric and trace element analysis. Results obtained at the air quality network of Extremadura for the gravimetric and multielemental analysis are presented for the 2008 campaign. Read more.

Determination of Zn(II) in undisturbed samples using the bismuth electrode

The journal Analytical Methods has just published our paper about the use of the bismuth bulk rotating disk electrode (BiB-RDE) as a new and advantageous alternative to determine heavy metal ions in undisturbed environmental and biological samples (pH 7.5) by anodic stripping voltammetry, with demonstrated applicability to the determination of Zn(II) in rainwater, tap water and urine. The proposed method benefits from the insensitiveness of the bismuth bulk electrode to the Bi(III) hydrolysis that affects the common “in situ” Bi film approach preventing its use at intermediate to alkaline pH. See the whole paper at http://dx.doi.org/10.1039/C4AY01626B

Filtrating-bulk passive sampling for elemental fractionation in atmospheric deposition

We have recently published the paper entitled "Fractionation of trace elements in total atmospheric deposition by filtrating-bulk passive sampling" in the journal Talanta. We have developed and validated a new simple and effective methodology for fractionation of soluble and insoluble forms of trace elements in total atmospheric deposition. The proposed methodology is based on the modification of a standard total deposition passive sampler by integrating a quartz fiber filter that retains the insoluble material, allowing the soluble fraction to pass through and flow to a receiving bottle. The quartz filter containing the insoluble fraction and the liquid containing the soluble fraction are then separately assayed by standardized ICP–MS protocols. The proposed atmospheric elemental fractionation sampler (AEFS) was validated by analyzing a Coal Fly Ash reference material with proper recoveries, and tested for field fractionation of a set of 10 key trace elements in total atmospheric deposition at the industrial area of Puchuncaví–Ventanas, Chile. The AEFS was proven useful for pollution assessment and also to identify variability of thes oluble and insoluble fractions of the selected elements within the study area, improving the analytical information attainable by standard passive samplers for total deposition without the need of using sophisticated and high cost wet-only/dry-only collectors.

New publication about screen printed electrode characterization

Our research group has just published a paper entitled "Characterisation of screen-printed gold and gold nanoparticle-modified carbon sensors by electrochemical impedance spectroscopy", in the Journal of Electroanalytical Chemistry. Gold-based screen-printed electrodes have been characterised by electrochemical impedance spectroscopy (EIS) to better understand their behaviour in electroanalytical applications, particularly in the anodic stripping voltammetry of Hg(II). After a first exploration by cyclic voltammetry, impedance spectra of gold-based screen-printed sensors were recorded in 0.1 M HCl electrolyte solution, in the presence of dissolved oxygen and with no electrochemical pre-treatment of the surface. The spectra demonstrated the differences in the interfacial characteristics of each kind of sensor. Structural changes in the surface of SPGEs caused by amalgam formation in the presence of Hg(II) were investigated by EIS. The results obtained were used to elucidate the implications for using the sensor in the stripping voltammetric determination of Hg(II) in environmental samples.