This study describes the preparation of a novel ion-imprinted polymer (IIP) to apply pre-concentration of cadmium ions in water samples of the Pontal Bay in Ilhéus, Brazil. First, cadmium ion was complexed with 2-(2-thiazolylazo)-p-cresol (TAC). Subsequently, there was the polymerization using ethylene glycol dimethacrylate and methacrylic acid monomers along with the radical azobisisobutyronitrile initiator. The mold ions were removed using 2:1 (v v-1) nitric acid. The thermal stability of the polymer was evaluated by thermogravimetry and the characterization was performed by Fourier transform infrared spectroscopy. The maximum adsorption capacity for IIP (qmax = 84.75 mg g-1) could be described by the Langmuir isotherm. The variables: sample flow rate, pH and eluent (nitric acid) were optimized using Box-Behnken design with determination by flame atomic absorption spectrometry (FAAS). The enrichment factor, as well as the limits of detection and quantification (LOQ), were found to be 44, 0.14 and 0.46 µg L-1, respectively. Selectivity was evaluated by using solutions containing CdII, CuII, NiII, PbII, CoII, SO42-, and Cl- ions. The concentration of cadmium ions in the samples varied between < LOQ to 1.25 µg L-1.

In the present paper, a preconcentration procedure based in the coprecipitation of copper by silver dichromate (Ag2CrO4) and consecutive determination by flame atomic absorption spectrometry (FAAS) was proposed. The experimental factors were optimized from application of the Doehlert matrix and the conditions set: chromate concentration 5.8 × 10-4 mol L-1, silver concentration 1.1 × 10-3 mol L-1, pH 7.3 and disperser concentration HNO3 0.38 mol L-1. Under these conditions, analytical parameters of the procedure were obtained, with the quantification limits of 0.76 µg L-1, precision (based in the relative standard deviation, RSD %) with values lower than 2.7%, and preconcentration factor of 28. The accuracy of the procedure was given by addition/recovery test in water samples groundwater and mineral, and by comparison with results obtained by ICP-MS. The procedure developed presented be simple, sensitive and low cost, thus can be applied in the preconcentration and determination of copper in several water samples.

In this work, it was developed an alternative analytical strategy for the preparation of vegetal samples extracted with diluted acids and assisted by ultrasound and microwave radiation for the determination of nutrients elements by fast sequential flame atomic absorption spectrometer. The conditions optimized using univariate and multivariate methodologies for the procedure were as follows: 200 mg of sample; extraction solution comprising a mixture of 6.3 mL HNO3, 2.1 mL HCl, and 1.7 mL CH3COOH; extractor with a final concentration of 2.5 mol L-1; a sonication time of 30 min; and a microwave radiation time of 6 s. The accuracy of the procedure was confirmed by analyzing the certified reference material NIST 1515 (apple leaves) and by comparison with the results obtained through microwave-assisted total digestion method. The procedure was applied to determine Ca, Mg, Cu, Mn, Fe, and Zn in several cassava peel samples used in animal nutrition, and proved to be simple, reliable, fast, easy to implement, and inexpensive.

This study proposes an optimized procedure for the determination of inorganic antimony species in natural waters using hydride generation atomic fluorescence spectrometry (HG AFS) and continuous flow system. The variables of the hydride generation system, such as pre-reduction time, hydrochloric acid concentration and sodium tetrahydroborate concentration, were evaluated using full factorial design at two levels and Doehlert design. After optimized experimental conditions, the method allowed the determination of antimony with limits of detection and quantification of 9 and 30 ng L-1, respectively. The precision (RSD) of the method was < 5% and the accuracy was confirmed by the analysis of certified reference material (SLRS-4, River water for trace metals). The method was successfully applied for inorganic antimony speciation in water samples collected in Salvador City, Bahia State, Brazil. In mineral water, total Sb concentrations ranged from 0.26 to 0.30 µg L-1, whereas the concentrations of SbIII were below 0.03 µg L-1. On the other hand, in natural surface waters, the quantifiable concentration of total Sb and SbIII ranged from 0.41 to 1.23 µg L-1 and 0.23 to 1.04 µg L-1, respectively. The highest average concentrations of Sb were obtained in regions with the largest urban influence, ratifying the anthropogenic impact in water bodies.