Direct determination of lanthanides in environmental samples using ultrasonic nebulization and ICP OES

Baixas concentrações dos catorze elementos de ocorrência natural da série lantanídeos foram diretamente determinadas por espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES). Avaliaram-se interferências espectrais e linhas espectrais mais adequadas foram selecionadas. Os desempenhos da nebulização pneumática e ultra-sônica foram comparados com respeito aos limites de detecção, para ambas as posições de observação do plasma, radial e axial. A influência da potência de radiofrequência sobre a precisão e exatidão foi também investigada para os dois tipos de nebulizadores. O método foi aplicado à determinação dos lantanídeos em amostras ambientais (sedimentos, cinza de carvão e água fluvial). Este trabalho demonstrou que é possível a determinação direta de baixas concentrações (i.e. ng g-1 e ng L-1) dos lantanídeos de ocorrência natural por ICP OES.Low concentrations of the fourteen naturally occurring lanthanides were directly determined by inductively coupled plasma optical emission spectrometry (ICP OES). Spectral interferences were evaluated and the most appropriate spectral lines selected. Pneumatic and ultrasonic nebulization performances were compared with respect to limits of detection for both radial and axial viewed plasma. The influence of plasma applied power on precision and accuracy was studied for both nebulizers. The developed method was applied to lanthanides determination in environmental samples (sediments, coal fly ash and river water). This work demonstrates that the use of ultrasonic nebulization combined with axially viewed plasma allowed direct determination of low concentrations (at ng g-1 and ng L-1 levels) of all naturally occurring lanthanides by ICP OES

Procedimento para a extração de mercúrio de sedimento marinho

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Estudo comparativo de métodos de preparo de amostras de tinta para a determinação de metais e metalóides por técnicas de espectrometria atômica

This work deals with paint decomposition methods for major, minor and trace elements determination. Three methods were investigated: (1) decomposition in closed quartz vessel and heating in microwave oven; (2) decomposition in open vessel using HNO3 and ashing, following the ASTM D 3335-85a method; and (3) decomposition in open vessel using HNO3 + HF and ashing. Paints of different types and colours were analyzed, in which several elements were determined using inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP OES). It was observed that method (1) is appropriate for trace, minor and major elements determination, while method (3) is appropriate for Ti

Mercury speciation in urban landfill leachate by cold vapor generation atomic absorption spectrometry using ion exchange and amalgamation

This work deals with on line speciation of organic Hg (Hg org) and inorganic Hg (Hg inorg) in urban landfill leachate. Chlorocomplexes of Hg inorg are produced in HCl medium and retained on an anion exchange column. The retained Hg is eluted with NaBH4 in presence of HCl. Hg0 is produced and then measured by cold vapor atomic absorption spectrometry (CV AAS). Hg org does not interact with the resin and is mixed with NaBH4 at the exit of the column producing volatile species of Hg that are then amalgamated by a gauze of Au/Pt. Mercury is removed from the gauze by heating to 600 °C and subsequently measured by CV AAS. For Hg inorg and Hg org speciation in urban landfill leachate, the samples are centrifuged, filtered and treated with HCl. The detection limits (3 s) of Hg inorg and Hg org are 9 and 12 ng L-1 of Hg, respectively. The analysis frequency is 22 h-1

Uso da valorização eletrotérmica para a introdução de amostras no ICP-MS /

Tese (Doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas

The use of cloud point extraction and hydride generation for improving the SB and Se limits of detection in ICP OES

O presente estudo trata da aplicação da extração no ponto nuvem (CPE) e geração de hidretos (HG) para a determinação de Sb e Se por espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES). O complexante utilizado foi o dietilditiofosfato de amônio (DDTP), enquanto que Triton X-114 foi usado como surfactante para a formação das micelas. As condições para a pré-concentração de Sb(III) e Se(IV), redução de Se(VI) e Sb(V), geração dos respectivos hidretos e interferências foram avaliadas e discutidas. O desempenho da HG foi comparado com o da nebulização pneumática (PN) para introduzir a fase rica em surfactante no plasma. Mediante aplicação da HG, os limites de detecção obtidos para Se(IV) e Sb(III) foram 0,05 e 0,08 µg L-1, respectivamente. No caso da aplicação da PN, os limites de detecção do Se(IV) e Sb(III) foram 0,90 e 2,90 µg L-1, respectivamente. Foram analisadas amostras de nozes e castanha do Pará, água e vinho branco. O Se(IV) foi quantificado na castanha do Pará, enquanto que o Sb(III) foi quantificado em água de estuário, água de mar e água mineral embalada em garrafa feita de politereftalato de etileno (PET).This study deals with the application of cloud point extraction (CPE) and hydride generation (HG) for determination of Sb and Se using inductively coupled plasma optical emission spectrometry (ICP OES). The complexing agent was ammonium diethylditiophosphate (DDTP), whereas Triton X-114 was used as surfactant for the formation of micelles. Conditions for Sb(III) and Se(IV) preconcentration, reduction of Se(VI) and Sb(V), hydrides generation and interferences were discussed. The performance of HG was compared with pneumatic nebulization (PN) for introducing the surfactant-rich phase into the plasma. Upon application of HG, the limits of detection (LODs) for Se(IV) and Sb(III) were 0.05 and 0.08 mg L-1, respectively. Limits of detection using PN were 0.90 and 2.90 ug L-1 for Se(IV) and Sb(III), respectively. Samples of nuts, water and white wine were analyzed. Selenium(IV) was quantified in Brazil nut whereas Sb(III) was in estuarine water, seawater and mineral water stored in polyethylene terephthalate (PET) bottle