Analysis of impurities in crude and highly-purified terephthalic acid by capillary electrophoresis

Autor(es)

Maria de Lourdes L. Moraes ^[1] ; Joel C. Rubim ^[2] ; Rene R. Realpozo ^[3] ; Marina F. M. Tavares ^[4]

Afiliação do(s) autor(es)

^[1] Universidade de São Paulo. Instituto de Química - Brasil

^[2] Universidade de São Paulo. Instituto de Química - Brasil

^[3] Tereftalatos Mexicanos S.A. - México

^[4] Universidade de São Paulo. Instituto de Química - Brasil

• Tipo de documento: Artigo Científico
• Fonte: Journal of the Brazilian Chemical Society; v. 15, n. 3, p. 400-406, 2004-06-00.

Resumo

In this work, a simple and fast capillary electrophoresis method for the simultaneous analysis of 4-carboxybenzaldehyde (4-CBA), p-toluic acid (pTOL) and benzoic acid (BZ) in industrial batches of crude (CTA) and highly-purified (PTA) terephthalic acid was developed. The electrophoretic conditions comprise: 20 mmol L-1 tetraborate buffer at pH 9, hydrodynamic injection (5 s/17 kPa), applied voltage of +30 kV and direct UV detection at 200 nm. The concentrations of 4-CBA and pTOL in five batches of CTA and four batches of PTA as determined by the proposed CE methodology were in agreement with the results from gas chromatography and polarography methods in current use in Tereftalatos Mexicanos S.A. (TEMEX). Levels of BZ were determined only by the CE methodology and ranged from 60 - 300 ppm in CTA and 5 - 7 ppm in PTA. Several impurities deriving from the incomplete oxidation of p-xylene were investigated. So far the positive identification of 4-hydroxymethylbenzoic acid was accomplished by comparison with pure standards. (AU)

• Processo FAPESP: 97/04595-4 - Avaliação comparativa das estratégias para aumento de sensibilidade em eletroforese capilar
• Beneficiário: Maria de Lourdes Leite de Moraes
• Modalidade de apoio: Bolsas no Brasil - Doutorado