Investigações envolvendo titulação termometrico catalitica

AUTOR(ES)
DATA DE PUBLICAÇÃO

1989

RESUMO

The influence of the composition of titrand and titrant on the shape of titration graph involved in the alkalimetric titration of acids in water-dimethylsulfoxide-acrylonitrile medium by catalytic thermometric titrimetry has been investigated. In this study it was possible to suggest the reaction responsible for the rise in temperature for different compositions of titrant and titrand and to make the choice of the more suitable combination of titrand and titrant for these titrations. Next, this technique was employed for the determination of acidic groups of the amino acids hystidine and arginine and of the proteins trypsin and myoglobin. It was observed that besides amino groups the groups imidazol and guanidine are titrated in the amino acids hystidine and arginine, respectively. In the case of proteins the influence of solvent system on the solubility and on the shape of tritation graph was investigated. Finnaly the use of thermochromic substances, such as solid solution of Cu2[HgI4] and Ag2[HgI4] and cholesteric liquid crystals, as end point indicator in catalytic thermometric titrimetry was studied. Solid solution of Cu2[HgI4] and Ag2[HgI4] wa employed as visual end point indicator in the alkalimetric titration of benzoic acid and acetylsalicilic acid both pure and in pharmaceutical preparations. Cholesteric liquids crystals were used as end point indicator in the alkalimetric titration of acetyl-salicilic acid, both pure and in pharmaceutical. preparations, and acidimetric titration of caffeine in pharmaceutical preparations and in soft drinks.

ASSUNTO(S)

termometro e termometria catalise quimica

ACESSO AO ARTIGO

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