Novo método espectrofotométrico para determinação de Hg (II) em amostras de peixe

Um novo método espectrofotométrico simples, sensível e com boa seletividade é apresentado para a determinação rápida de mercúrio (II) em nível de traços com 2-mercapto-5-metilbenzilimidazol (MMBI) como um novo reagente espectrofotométrico (lambda max = 320 nm), em um meio aquoso ligeiramente alcalino (tampão Britton-Robinson (BR) 0,04 M, pH 8,0). A reação é instantânea e a absorbância permanece estável por mais de 24 horas. O coeficiente de absorção molar encontrado foi de 2,71 x 10(4) L mol-1 cm-1. A composição estequiométrica do complexo é de 1:1 (Hg:MMBI). Considerável excesso dos íons cobre, zinco, chumbo e cádmio não interfere na determinação. O método desenvolvido permitiu a determinação de mercúrio na faixa de 2 x 10-6 a 4 x 10-5 mol.L-1 com boa precisão e exatidão, e o limite de detecção para Hg foi de 9,9 x 10-7 mol.L-1. O método foi aplicado com sucesso a amostras de peixe e os resultados foram avaliados com o clássico método de espectrometria de absorção atômica (EAA). Os desvios padrão relativos para as amostras analisadas foram de 7,2 e 33% (n = 5), enquanto os erros foram de 1,63 e 11,6. O método mostrou-se sensível, seletivo e foi aplicado para a determinação de mercúrio em amostras de peixe com resultados satisfatórios.

Ehrewyrdige, wyrdige, hög- och wällerdeherrar, praepositi och pastores, uthi detta lofl. stiffet Åbo, ährade bröder i Christo

Nimeke otsikosta. - Teksti alkaa: Ehr- och w:ter är nogsampt kunnigt aff det som bland annat ...

Ett bref, som then hög-ähre-wyrdige och höglärde biskoppen, h:r Johan Gezelius, skrifwit til thet wyrdige prästerskapet i det loflige Åbo stifft

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HG 186.9-187.0 D.E-1

Coarse grained sediment with a few fine grained matrices. Brown sediment with small to medium sized clasts. Clasts range from sub-angular to sub-rounded. Organic material present.

HG 186.9-187.0 D.E-2

Coarse grained sediment with small patches of a fine grained domain. The domain may contain organic material. Lineations and minor grain stack present throughout the section.

HG 186.9-187.0 D.E-3

Fractured and weathered grains throughout the section. Lineations and grain stacks throughout the section.

HG 186.9-187.0 D.E-4

Fine grained domain within a coarse grained domain. Lineations throughout the section. A few small patches of a clay domain seen towards the top left.

HG 186.15-186.25-1

Coarse grained section with two different fine grained domains. Towards the left hand side the domain is dark and has no inclusions of coarse grains. The right hand side has some coarser materials.

HG 186.15-186.25-2

Major grains crushing towards the top left with two fine grained domains in coarse grained sediment.

HG 186.15-186.25-3

Major grain crushing towards the centre of the section. A few lineations and grain stacks also present.

HG 186.55-186.75-1

Domain boundaries observed between the fine grained and coarse grained sediment. The coarse grained sediment contains lineations.

HG 186.55-186.75-2

Fine grained sediment, quite structure-less.

HG 186.15-186.25 Thin Section

Coarse grained sample with multiple fine grained domains. Clasts range from small to medium and sub-angular to sub-rounded. Mainly contains grain crushing (with grains crushed into one another) and short distance lineations. A few rotation structures are seen and fine grained sand domains can also be seen.

HG 186.80-186.85 Thin section

A coarse grained sample with clay rich domains. Grains range from small to medium and are sub-angular. Rotation structures can be seen around sub-rounded clasts. Lineations can be seen throughout the image, mainly short distance lineations. Small comet structures can also be seen throughout the images.

HG 186.9-187.0 D.E.

Coarse grained sediment with a few fine grained matrices. Brown sediment with small to medium sized clasts. Clasts range from sub-angular to sub-rounded. Organic material present. It contains rotation structures throughout as well as edge-to-edge grain crushing. Fine grained clay domains are present and lineations can also be seen. Minor amounts of grain stacking can also be seen.