SciELO - Scientific Electronic Library Online

 
vol.27 número especialCorrosion study of the SnO2-ZnO crucibles, in the melting of glasses contends heavy metalsExploratory analysis of inorganic constitution contents in grape juices and soft drinks índice de autoresíndice de materiabúsqueda de artículos
Home Pagelista alfabética de revistas  

Servicios Personalizados

Articulo

Indicadores

Links relacionados

  • No hay articulos similaresSimilares en SciELO

Compartir


Eclética Química

versión impresa ISSN 0100-4670

Resumen

SANTOS, Daniele Minholo et al. Analysis of inorganic constituents in milk and simulation of CFA-C reagent. Eclet. Quím. [online]. 2002, vol.27, n.spe, pp. 61-76. ISSN 0100-4670.  http://dx.doi.org/10.1590/S0100-46702002000200006.

Milk analysis can be successfully performed by dilution of samples with CFA-C, a commercial mixture of water-soluble tertiary amines, and measurements by inductively coupled plasma atomic emission spectrometry (ICP-OES). However, due to the costs of this reagent and contamination, the work here described investigated an alternative reagent that could be used instead of CFA-C. Qualitative analysis showed that the commercial mixture does not contain boric acid or EDTA. A potentiometric titration of a CFA-C 10% v/v aqueous solution using HCl as titrant showed two peaks and it was inferred that 90% of the acid was consumed for neutralization of free amines and the remaining 10% was consumed for protonation of an anion of a weak acid employed to generate a buffer R3N/R3NH+ with the molar ratio 10:1. For simulating the CFA-C reagent, it was prepared a solution containing 6.06 mol L-1 monoethanolamine (MEA) plus 0.20 mol L-1 citric acid, triprotic, to form a buffer 10:1. The citrate anion is a good chelating ligand for Ca(II). An other citrate buffer was prepared (1.52 mol L-1) using trishydroxymethylaminomethane (TRIS), which is an amine less soluble in water. These mixtures were characterized by potentiometric and thermal analysis. Both amine/citrate buffers presented a performance comparable to the commercial reagent.

Palabras llave : Milk; CFA-C; tertiary amines; ICP-OES.

        · resumen en Portugués     · texto en Portugués