Desenvolvimento de estratégias visando determinação e análise de especiação de antimônio em amostras ambientais

Abstract

This paper discusses analytical strategies for the determination and speciation analysis of antimony in environmental samples. Within this proposal, it was developed three methodologies. The first proposes a method for determining Sb full in fish muscle tissue using atomic absorption spectrometry with hydride generation (HG AAS). The optimization method was performed using full factorial design and Box-Behnken matrix. The process of digestion of the samples was established using microwave assisted radiation using concentrated nitric acid. The optimized conditions allowed the determination of total Sb using the external calibration technique, with limits of detection and quantification of 0.8 and 2.6 ng g-1, respectively, to a sample mass of 0.20 g and accurately expressed as the relative standard deviation 4.32% for a solution with Sb concentration of 5 ug L-1. The accuracy was confirmed by oyster tissue CRM analysis (NIST 1566b). The method was applied in seven samples of fish muscle tissue (Arraia - Rajiformes lasmobranquiomorpha) acquired in two regions of Baía de Todos os Santos, Bahia, Brazil. The Sb content found ranged 62-370 ng g-1. The second method proposes an extraction procedure for the speciation analysis of inorganic Sb sediment samples using sampling and HG AAS suspension. The optimization step was carried out using full factorial design and Box-Behnken matrix where the studied factors were: extraction temperature, ultrasound radiation time, and concentration of hydrochloric acid. With the optimized conditions, Sb species were extracted in a closed system using 6.0 M hydrochloric acid at a temperature of 70 ° C and an ultrasonic radiation time of 20 min. The determination of Sb was carried out by external calibration technique, with limits of detection and quantification of 0.70 and 2.34 ng g-1, respectively, and the precision expressed as relative standard deviation of 5.6% to one solution with Sb concentration of 6.0 ug L- 1. The accuracy of the method was confirmed by analysis of two sediment CRM for a mass 0.20 g. The method was applied to the analysis of six samples collected sediment in estuary São Paulo (Bahia, Brazil) and concentrations ranged from 45.3 to 89.1 ng g-1 for total Sb and 17.7 to 31, 4 ng g-1 for Sb (III). The third method proposes the use of an injection analysis system with flow multisyringe (MSFIA) for speciation analysis and determination of total inorganic and organic Sb in soil samples using (HG AFS). The optimization step was carried out using full factorial design and Doehlert matrix involving the following factors: the concentration of hydrochloric acid and concentration of sodium borohydride and sample flow. The optimized experimental conditions allowed the determination of Sb, using the external calibration technique limits of detection and quantification of 0.9 and 3.1 ng g-1, respectively, and precision expressed as relative standard deviation of 3, for a 2% Sb solution of 5.0 mg L-1. The accuracy of the method was confirmed by soil CRM analysis and addition / recovery tests. The proposed method was applied in soil samples collected from different locations of the Balearic Islands, Spain. Thirteen samples were analyzed and the results ranged 19-46 ng g-1 for organic antimony and 113-215 ng g-1 for total inorganic antimony.