Total Mercury Determination in Muscle and Liver Tissue Samples from Brazilian Amazon Fish Using Slurry Sampling

This paper presents a slurry sampling method for total mercury determination by graphite furnace atomic absorption spectrometry (GFAAS) in tissue of fish from the Amazon. The tissue samples were lyophilized and macerated, and then the slurry samples were prepared by putting 20 mg of tissue, added to a solution containing Triton X-100, Suprapur HNO3, and zirconium nitrate directly in sampling vials of a spectrometer. Mercury standard solutions were prepared under the same conditions as the slurry samples. The slurry samples and the mercury standard solutions were sonicated for 20 s. Twenty microliters of slurry samples were injected into the graphite tube, which contained an internal wall lined with tungsten carbide. Under these conditions, it was possible to thermally stabilize the mercury up to an atomization temperature of 1700 °C. The method was validated by mercury determination in reference materials DORM-4 and DOLT-4. The LOD and LOQ were 0.014 and 0.045 mg kg−1, respectively, and recovery percentages in relation to the concentration values were certified in the order of 98%

Desenvolvimento de metodologias analíticas para determinação de selênio, cobre e manganês por GFAAS em amostras de vegetais de cultura orgânica e convencional utilizando extração por ultra-som

No presente trabalho é proposto um método para determinação de cobre, manganês e selênio em amostras de vegetais de cultura orgânica e convencional utilizando ultra-som no processo de extração dos analitos e posterior quantificação por espectrometria de absorção atômica em forno de grafite (GFAAS). Utilizando como solução extratora HCl 0,10 mol L-1, as condições ótimas de extração estabelecidas foram: massa de amostra de 100 mg; granulometria da amostra < 60 m; tempo de sonificação de cinco ciclos de 40 s e potência de sonificação de 136 W. As determinações dos analitos por GFAAS foram feitas utilizando-se temperaturas de secagem de 90-250 oC, temperatura de pirólise de 1300 oC, temperatura de atomização de 2300 oC e temperatura de limpeza de 2800 oC. Foi utilizado como modificador químico nitrato de paládio co-injetado junto com as amostras e tungstênio como modificador permanente. A exatidão e precisão do método de extração proposto foram avaliadas utilizando-se padrão certificado Corn Bran, RM 8433 – National Institute of Standards and Technology. Os resultados obtidos pelo método de extração por ultra-som mostraram-se equivalentes aos obtidos pelo método utilizando-se mineralização ácida das amostras em forno de microondas. No entanto, a metodologia proposta diminui consideravelmente o tempo de análise, o que favorece a velocidade analítica. Além disso, a quantidade de resíduos gerados para o ambiente também é bastante minimizad

Total Mercury Determination in Muscle and Liver Tissue Samples from Brazilian Amazon Fish Using Slurry Sampling

This paper presents a slurry sampling method for total mercury determination by graphite furnace atomic absorption spectrometry (GFAAS) in tissue of fish from the Amazon. The tissue samples were lyophilized and macerated, and then the slurry samples were prepared by putting 20 mg of tissue, added to a solution containing Triton X-100, Suprapur HNO3, and zirconium nitrate directly in sampling vials of a spectrometer. Mercury standard solutions were prepared under the same conditions as the slurry samples. The slurry samples and the mercury standard solutions were sonicated for 20 s. Twenty microliters of slurry samples were injected into the graphite tube, which contained an internal wall lined with tungsten carbide. Under these conditions, it was possible to thermally stabilize the mercury up to an atomization temperature of 1700 °C. The method was validated by mercury determination in reference materials DORM-4 and DOLT-4. The LOD and LOQ were 0.014 and 0.045 mg kg−1, respectively, and recovery percentages in relation to the concentration values were certified in the order of 98%

Analytical procedure based on slurry sampling for determining selenium in organic vegetable samples by graphite furnace atomic absorption spectrometry

This paper presents a simple, fast and sensitive method to determine selenium in vegetable samples by graphite furnace atomic absorption spectrometry through the direct introduction of slurries of the samples into the spectrometer's graphite tube. The limits of detection and quantification calculated for 20 readings of the blank of the standard slurries (5 mg mL(-1) of microcrystalline cellulose) were 0.33 and 1.10 mu g L(-1). The proposed method was applied to determine selenium in samples of organically grown vegetables and its results proved compatible with those obtained from samples mineralized by acid digestion in a microwave oven.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Evaluation of Cu, Mn, and Se in Vegetables Using Ultrasonic Extraction and GFAAS Quantification

This paper proposes a method for the determination of copper, manganese, and selenium in vegetables of conventional and organic farming in the state of So Paulo/Brazil using ultrasonic extraction of analytes and subsequent quantification by graphite furnace atomic absorption spectrometry (GFAAS). Using 0.10 mol L(-1) of hydrochloric acid as the extracting solution, the following optimal extraction conditions were established: sample mass of 100 mg, sample grain size of < 60 mu m, sonication time of five cycles of 40 s, and sonication power of 136 W. The analytes were determined by GFAAS, applying drying temperatures of 90 A degrees C to 250 A degrees C, pyrolysis temperature of 1,300 A degrees C, atomization temperature of 2,300 A degrees C, and cleaning temperature of 2,800 A degrees C. Palladium nitrate was co-injected with the samples as a chemical modifier and tungsten as a permanent modifier. The accuracy and precision of the proposed extraction method were evaluated based on a certified standard, RM 8433 Corn Bran (NIST RM 8433). The results obtained by the ultrasonic extraction method were equivalent to those obtained by the method of acid mineralization of samples in a microwave oven. However, the proposed methodology reduces the analytical time considerably, favoring the analytical speed. Moreover, the quantity of residues generated and discharged into the environment is also considerably lower.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq