18 research outputs found
Multivariate optimization and validation of an analytical method for the determination of cadmium in wines employing ET AAS
This work describes the optimization and validation of a direct method employing electrothermal atomic absorption spectrometry (ET AAS) for the determination of cadmium in wine. The optimization step was carried out using a two-level full factorial design, involving the followings factors: pyrolysis time (10 s) and temperature (600 ÂşC), atomization temperature (1300 ÂşC) and modifier mass (15 µg). Under the optimized conditions, a characteristic mass of 0.7 pg and limits of detection and quantification of 0.030 and 0.100 µg L-1, respectively, were obtained using a sample volume of 20 µL. The precision expressed as relative standard deviation (RSD %) was 0.30, 0.37 and 0.49% for wines with cadmium concentrations of 1.286, 0.266 and 0.356 µg L-1, respectively. The accuracy of the new direct determination methodology applying ET AAS was assessed by comparison with an acid digestion methodology, also with determination by ET AAS, using five wine samples. The proposed method was applied for the determination of cadmium in 30 Brazilian wine samples. The cadmium content varied from 0.146 to 1.563 µg L-1; all these values are lower than the permissible maximum level stipulated by the International Organization of Vine and Wine (OIV) and also by Brazilian legislation, which is 10 µg L-1.O presente trabalho descreve a otimização e validação de um mĂ©todo para determinação direta de cádmio em amostras de vinho por espectrometria de absorção atĂ´mica com atomização eletrotĂ©rmica (ET AAS). A otimização foi realizada empregando um planejamento fatorial completo de 2 nĂveis, incluindo os fatores: tempo (10 s) e temperatura de pirĂłlise (600 ÂşC), temperatura de atomização (1300 ÂşC) e massa de modificador (15 µg). Sob as condições otimizadas, foi encontrada uma massa caracterĂstica de 0,7 pg, limite de detecção e quantificação de 0,030 e 0,100 µg L-1, respectivamente, para um volume de amostra de 20 µL. A precisĂŁo foi de 0,30, 0,37 e 0,49% (RSD) para amostras de vinho com concentrações de 1,286, 0,266 e 0.356 µg L-1, respectivamente. A exatidĂŁo da metodologia de determinação direta empregando ET AAS foi avaliada por comparação usando um mĂ©todo de digestĂŁo ácida e determinação tambĂ©m por ET AAS para cinco amostras de vinho. O mĂ©todo foi aplicado para determinação de cádmio em 30 amostras de vinhos brasileiros. A concentração de cádmio variou de 0,146 a 1,563 µg L-1, cujos valores estĂŁo abaixo do nĂvel máximo permitido pela Organização Internacional de Vinha e Vinho (OIV) e pela legislação brasileira, 10 µg L-1.788794Conselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de NĂvel Superior (CAPES
Borboletas (Lepidoptera: Hesperioidea e Papilionoidea) do campus da Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul
Diversidade de borboletas (Lepidoptera, Papilionoidea e Hesperioidea) em fragmentos de Floresta Estacional Decidual em Santa Maria, Rio Grande do Sul, Brasil
Determination of triazines in hemodialysis saline solutions by adsorptive stripping voltammetry after extraction in acetonitrile
A method for the voltammetric determination of 2-methylthio-4,6-dialkylamino-1,3,5-triazine (triazines) herbicides in hemodialysis (HD) saline solutions was developed. The herbicides were detected in the saline solutions at the hanging mercury drop electrode (HMDE) with high sensitivities only after extraction of the analytes in acetonitrile (ACN). The salting out effect originated by the saline environment existing in the solutions enabled the extractions. The volume ratio between the saline and ACN phases was investigated in order to find the best sensitivity to detect the triazines. The speciation amongst them (ametryn, desmetryn, prometryn and terbutryn) was not possible. Recoveries between 88 and 107% were calculated in spiked samples, and detection limits of 0.03 mumol L-1 were calculated for the triazines in the saline samples using this methodology