Indigo Carmine degradation by hypochlorite in aqueous medium monitored by electrospray ionization mass spectrometry |
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| Authors: | Ana P F M de Urzedo Clésia C Nascentes Maria E R Diniz Rodrigo R Catharino Marcos N Eberlin Rodinei Augusti |
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| Institution: | 1. Department of Chemistry, Federal University of Minas Gerais ‐ UFMG, Belo Horizonte, MG, 31270‐901, Brazil;2. Thomson Mass Spectrometry Laboratory, Institute of Chemistry, State University of Campinas, 13083‐970, Campinas, SP, Brazil;3. Department of Chemistry, Federal University of Minas Gerais ‐ UFMG, Belo Horizonte, MG, 31270‐901, BrazilDepartamento de Química, Universidade Federal de Minas Gerais, Belo Horizonte/MG, Brazil. |
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| Abstract: | The degradation of the dye Indigo Carmine by hypochlorite in aqueous solution was monitored by electrospray ionization mass spectrometry in the negative ion mode (ESI(—)‐MS). Hypochlorite was highly efficient in removing the color of aqueous solutions of the dye. ESI(—)‐MS monitoring showed that concomitant with the Indigo Carmine consumption two transient species appeared (detected as doubly charged anions) probably formed via a net insertion of two hydroxyl groups at the exocyclic C?C bond followed by the incorporation of two (mainly) or one oxygen atoms at the indolic rings of the dye. Structures of these products were proposed based on the ESI(—)‐MS/MS data and high accuracy mass measurements. These two transient intermediates quickly decomposed, both in the condensed and in the gas phase, to yield mono‐charged anions. Based on these results, a route for the Indigo Carmine degradation by hypochlorite in aqueous solution has been proposed. Copyright © 2007 John Wiley & Sons, Ltd. |
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