Filho H.R.S.,University Estadual do Sudoeste hia |
Oliveira D.M.,University Estadual do Sudoeste hia |
Lemos V.A.,University Estadual do Sudoeste hia |
Bezerra M.A.,University Estadual do Sudoeste hia
Journal of the Brazilian Chemical Society | Year: 2015
This work proposes the use of multivariate optimization as a procedure for cadmium determination in leachate samples via flame atomic absorption spectrometry after solid phase extraction using a minicolumn packed with Amberlite XAD-4 modified with 3,4-dihydroxybenzoic acid. The variables related with the preconcentration (pH, sampling flow rate and buffer concentration) were optimized using Doehlert design. Two statistical modeling tools (least squares regression and artificial neural networks) have been applied to the data and their performances were compared. Digestion procedures of the leachate by heating in acid medium and ultraviolet radiation were evaluated being the latter more appropriate to prevent loss of Cd by volatilization. The developed procedure has promoted an enrichment factor of 9, with detection and quantification limits (3sb) of 0.72 and 2.4 μg L-1, respectively, and precision - expressed as relative standard deviation percentage - of 4.0 and 6.4% (RSD%, n = 4 for 5.0 and 20.0 μg L-1, respectively). Addition/recovery tests for Cd were carried out and values between 97 and 112% were obtained. The procedure was applied for cadmium determination in leachate samples collected at the sanitary landfill of Jaguaquara-BA, Brazil. ©2015 Sociedade Brasileira de Química.
Santos A.S.D.,Federal University of Triângulo Mineiro |
Tribess S.,Federal University of Triângulo Mineiro |
Pinto L.L.T.,Federal University of Triângulo Mineiro |
Ribeiro M.D.C.L.,Federal University of Triângulo Mineiro |
And 2 more authors.
Motricidade | Year: 2014
The aim of this study was to analyze the walking speed as a discriminator of functional disability. This was an epidemiological cross-sectional study with a random sample of 622 individuals, in the age group 60-96 years, mean 71.6 years (SD= 7.39) for men and 70.78 years (SD= 7.96) for women. Receiver operating characteristic (ROC) curves were designed and the criterion discriminator of 2.44 meters walking speed (in seconds) were determined in order to predict the absence of functional disability in basic activities of daily living (BADL) and instrumental activities of daily living (IADL). The areas under the ROC curve for the analyzes were higher 0.60 suggesting that the walk test has the potential to discriminate functional impairment, in BADL and IADL in both sexes. Walking time to discriminate functional disability was higher than 3.53 seconds for BADL and 2.47 seconds in IADL for men. For women, it was higher than 3.41 seconds for BADL and 3.19 seconds in IADL. The time of walking speed can be monitored in surveys and interventions population as indicator of functional disability in the elderly. © Edições Desafio Singular.
Santos L.D.,University Estadual do Sudoeste hia |
Santos Q.O.D.,University Estadual do Sudoeste hia |
Moreno I.,University Estadual do Sudoeste hia |
Novaes C.G.,University Estadual do Sudoeste hia |
And 2 more authors.
Journal of the Brazilian Chemical Society | Year: 2016
A simultaneous preconcentration method for cadmium, copper and nickel in samples of sediments and determination by inductively coupled plasma optical emission spectrometry was developed. The method is based on the extraction of the metals as complexes formed with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (5-Br-PADAP) at cloud point of the nonionic surfactant polyethylene glycol tert-octylphenyl ether (triton X-114). Optimization was performed using a Doehlert design and constrained mixture design. Desirability function was used to provide a simultaneous optimization of the evaluated responses. The developed method presented limits of quantification of 0.066, 0.149 and 0.191 μg g-1 and an enrichment factor of 18.4, 16.8 and 18.2 fold for cadmium, copper and nickel, respectively. The proposed method was applied in sediment samples collected in the urban stretch of the Contas River (Jequié, BA, Brazil). Adequate accuracy was found by analysis of two certified reference materials (NIST 1646a estuarine sediments and NIST 2702 marine sediment). ©2016 Sociedade Brasileira de Química.