Luminescent hybrid thin films in the fibroin-siloxane-lanthanides system
| Full text | |
| Author(s): |
Daniele Minholo Santos
[1]
;
Ana Rita Araujo Nogueira
[2]
;
Eduardo Fausto Almeida Neves
[3]
;
Éder Tadeu Gomes Cavalheiro
[4]
;
Joaquim Araújo Nóbrega
[5]
Total Authors: 5
|
| Affiliation: | [1] UFSCar. Departamento de Química - Brasil
[2] EMBRAPA. Embrapa Pecuária Sudeste - Brasil
[3] UFSCar. Departamento de Química - Brasil
[4] UFSCar. Departamento de Química - Brasil
[5] UFSCar. Departamento de Química - Brasil
Total Affiliations: 5
|
| Document type: | Journal article |
| Source: | Eclética Química; v. 27, p. 61-76, 2002-00-00. |
| Abstract | |
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. (AU) | |
| FAPESP's process: | 98/10814-3 - Preparation of agronomic samples and multi-elementary determination by induced plasma atomic emission spectrometry |
| Grantee: | Joaquim de Araújo Nóbrega |
| Support Opportunities: | Research Projects - Thematic Grants |