Direct determination of Al and Pb in waste printed circuit boards (PCB) by laser-induced breakdown spectroscopy (LIBS): Evaluation of calibration strategies and economic - environmental questions

Matrix-matching calibration (MMC), two-point calibration transfer (TP CT), one-point and multi-line calibration (OP MLC), single-sample calibration (SSC) and calibration free (CF) were evaluated in order to overcome matrix effects in laser-induced breakdown spectroscopy (LIBS). These calibration strategies were evaluated for direct determination of Al and Pb in waste printed circuit boards (PCB) using direct solids analysis by LIBS. Each strategy has limitations and advantages of its implementation, for the correction of matrix effects, so that it allows elementary determination with adequate accuracy. The MMC and CF proved to be excellent calibration strategies for the determination of strategic (Al) and toxic (Pb) elements by LIBS, with good recoveries (ranging from 80–120%) and low relative standard deviation (RSD%) values. A detailed discussion of the advantages and limitations of each of these five calibration strategies evaluated for LIBS is presented in this study. Lead concentrations in waste PCB samples are 5–12 times higher than established by Directive 2011/65/EU, and the samples analyzed contain between 3 and 55 g kg-1 Al, being an interesting economic and recycling source for this metal

Employment of factorial design for optimization of pirolisys and atomization temperatures for Al, Cd, Mo and Pb determination by ETAAS

This work describes a factorial design for the optimization of pyrolysis and atomization temperatures in ETAAS. As examples, Cd and Pb were determined using lower pyrolysis and atomization temperatures and Al and Mo with higher pyrolysis and atomization temperatures. Good results were obtained for Cd employing Rh (m o = 1.4 pg) as a permanent modifier with pyrolysis and atomization temperatures of 640 and 1500 °C, respectively. For Zr, W or Zr+W, the Cd pyrolysis and atomization temperatures were 500 and 1500 °C, respectively, with m o = 1.4 pg using Zr or W and 1.5 pg using Zr+W. The best results for Pb were those using Rh, Zr, W and Zr+Rh, obtaining characteristic masses of 42, 37, 34 and 36 pg, respectively. Pyrolysis and atomization temperatures of 910 and 1850 °C, respectively, were achieved for this metal. For Al, the best results were obtained when Zr or Zr+W were used. Mo was also tested as a possible permanent modifier for Al, but the results were not satisfactory. The results obtained for Mo without modifier were similar to those with conventional modifiers (Mg or Pd+Mg) and the results obtained using permanent chemical modifiers were not satisfactory. In all situations, the experiments were performed faster than those using the univariate procedure.246253Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Analysis of waste electrical and electronic equipment (WEEE) using laser induced breakdown spectroscopy (LIBS) and multivariate analysis

This study shows the application of laser induced breakdown spectroscopy (LIBS) for waste electrical and electronic equipment (WEEE) investigation. Several emission spectra were obtained for 7 different mobiles from 4 different manufacturers. Using the emission spectra of the black components it was possible to see some differences among the manufacturers and some emission lines from organic elements and molecules (N, O, CN and C2) led to the highest contribution for this differentiation. Some polymeric internal parts in contact with the inner pieces of the mobiles and covered with a special paint presented a strong emission signal for Cr. The white pieces presented mainly Al, Ba and Ti in their composition. Finally, this study developed a procedure for LIBS emission spectra using chemometric strategies and suitable information can be obtained for identification of manufacturer and counterfeit products. In addition, the results obtained can improve the classification for establishing recycling strategies of e-waste.The authors are grateful to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES- DGU, Grant 243/11), to the Spanish Government (Projects CTQ2008-06730-C02-01, CTQ2011-23968 and PHB2010-0018-PC), to Conselho Nacional de Desenvolvimento Científico e Tecnológico, CNPq (grants 304772/2012-7 and 474357/2012-0), and to Grant 2012/01769-3, São Paulo Research Foundation (FAPESP) for the financial support

Removal of copper(II) from sugar-cane spirits employing chitosan

A method employing chitosan as complexant agent in the removal of copper(II) ions generally present in the Brazilian cachaça samples is herein proposed. The efficiency of this method is attributed to its high capacity of metal cations adsorption, mainly due to presence of hydroxyl and amine groups that can serve as chelating sites. The removal of copper(II) ions from this alcoholic beverage was efficient employing either in column and batch system. The analysis were carried out employing the flame atomic absorption spectrometry and the remaining copper(II) concentrations in the treated cachaça were lower than LOD of FAAS technique

Evaluation of ICP OES with axial or radial views for determination of iodine in table salt

The performance of inductively-coupled plasma optical emission spectrometers with axial and radial views for determination of iodine in table salt was evaluated. Interference and memory effects in nitric acid and water-soluble tertiary amines (CFA-C) media were studied. Based on a factorial experiment, one optimum instrument operational condition for axial configuration, and two optima conditions for radial configuration was established. The ICP OES with axial view was 5-fold more sensitive than the radial view. Both matrix matching and standard addition methods were used for iodine quantification and for most samples, both strategies of calibration led to similar results. Recoveries ranged from 104 to 114%

Polymeric nanoparticles loaded with the 3,5,3'-triiodothyroacetic acid (Triac), a thyroid hormone: factorial design, characterization, and release kinetics

This present investigation deals with the development and optimization of polymeric nanoparticle systems loaded with 3,5,3′-triiodothyroacetic acid (Triac). A '2 POT. 11-6' fractional factorial design and another '2 POT. 2' factorial design were used to study the contrasts on particle size distribution, morphology, surface charge, drug content, entrapment efficiency, and in vitro drug release profiles. The independent variables were the concentration of Triac, type and quantity of both polymer and oil, quantity of Span™ 60 and Tween® 80, volume of solvent and water, and velocity of both magnetic stirring and the transfer of the organic phase into the aqueous solution. The results of optimized formulations showed a narrow size distribution with a polydispersity index lower than 0.200. The particle sizes were on average 159.6 nm and 285.6 nm for nanospheres and nanocapsules, respectively. The zeta potential was higher than 20 mV (in module) and the entrapment efficiency was nearly 100%. A high-performance liquid chromatography method was developed, validated, and efficiently applied to Triac quantification in colloidal suspension. The main independent variables were the type and quantity of the polymer and oil. In vitro drug release profile depicted several features to sustain Triac release. Different formulations showed various release rates indicating an interaction between Triac and other formulation compounds such as polymer and/or oil quantity. Two different models were identified (biexponential and monoexponential) that allowed the control of both the release rate and Triac concentration. Thus, the prepared nanoparticles described here may be of clinical importance in delivering Triac for thyroid treatment.CNPqFAPES

Investigation of hypovitaminosis D in patients infected with SARS-CoV-2 and its relationship with clinical worsening: a cross-sectional observational retrospective clinical study

Numerous studies have demonstrated the profile of infection and symptoms related to COVID-19 that occur with pulmonary manifestations (such as Acute Respiratory Syndrome), digestive symptoms, anosmia, and ageusia. Many comorbidities have been associated with deaths and severe cases of the disease, such as diabetes, hypertension, obesity, and heart disease. However, many questions remain unanswered, especially the association of disease severity with hypovitaminosis D. Vitamin D deficiency is widely found in patients in Intensive Care Units, and recent studies have shown that it has been suggested that patients with severe manifestations of COVID-19 have hypovitaminosis D. Therefore, the present study aims to associate the presence of hypovitaminosis D in patients with the acute respiratory syndrome, positive for SARS-COV-2, admitted to the José Alencar Regional Hospital in Uberaba/Brazil and the evolution of the disease (days of hospitalization, hospitalization in the ICU, discharge and death) through the analysis of vitamin D (25(OH)D) hospitalized patients clinical records. The incidence of hypovitaminosis D among the patients was also assessed. The results may contribute to the understanding of the disease, as well as the need for vitamin supplementation

Nanopartículas de poli-'épsilon'-caprolactona carregadas com hidrocortisona: preparação usando planejamento fatorial e sua avaliação

Polymeric-nanoparticle systems such as nanocapsules and nanospheres have a great potential in applications for nanoencapsulation of corticosteroids which show low solubility in water. The physicochemical characteristics of nanoparticle suspensions are important pre-requisites for the successful development of new dosage form. In this study, hydrocortisone-loaded poly-ε-caprolactone nanoparticles have been prepared by the interfacial deposition method. A 3-factor 2-level factorial design was used to study and optimize nanoparticles formulation. This factorial design was used to study the contrasts and effects of independent variables on particle size distribution, morphology, surface charge, drug content, entrapment efficiency and in vitro drug release profiles. The screened independent variables were: the concentration of hydrocortisone, poly-ε-caprolactone and isodecyl oleate. A High Performance Liquid Chromatography method was developed and validated for hydrocortisone quantification. Special attention was given to both absolute recovery and entrapment efficiency. The results of optimized formulations showed a narrow size distribution with a polydispersity index near to 0.200. The particle sizes were on average 109.2 and 236.5nm to nanospheres and nanocapsules, respectively. In the best formulations the zeta potential was higher than 30 mV (in module) and the absolute recovery and entrapment efficiency were higher 82% and nearly 60%, respectively. The main variables were the quantity of the polymer and of the oil. Nanoparticles observed by the Scanning Electron Microscope depicted extremely spherical shape. In vitro release studies were performed through dialysis with continuous stream. Nanocapsules and nanospheres showed a similar pure diffusion release mechanism according to Korsmeyer-Peppas’s model.CNPqCAPESFAPES

Sequential Determination of Cd, Cu and Pb in Tea Leaves by Slurry Introduction to Thermospray Flame Furnace Atomic Absorption Spectrometry

A simple procedure for the sequential determination of Cd, Cu and Pb in tea leaves by slurry introduction to thermospray flame furnace atomic absorption spectrometry was developed. Detection limits were 0.05 mg kg-1 for Cd, 2.1 mg kg-1 for Cu and 0.68 mg kg-1 for Pb using 0.67 % (m/v) slurries (100 mg/15 mL). © 2013 Springer Science+Business Media New York