Direct inlet mass spectrometry for a rapid characterization of indigo in lipidic and proteinaceous matrices

BLANCA A. GÓMEZ; DIANA CASTELLANOS RODRIGUÉZ; VALERIA P. CAREAGA; GABRIELA SIRACUSANO; MARTA S. MAIER

MICROCHEMICAL JOURNAL

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 p. 21 - 28

0026-265X

Direct inlet mass spectrometry (DI-MS) was examined for its suitability to quickly identify indigo in mixtureswith lipidic and proteinaceous binders, such as those characteristic of paintings and polychromy. The techniquewas tested on naturally aged reference mixtures of indigo with linseed oil, rabbit skin glue, and whole egg. DI-MSwith electron ionization at 70 eV served as an efficient tool for screening indigo in complex matrices and provided,at the same time, a mass spectral fingerprint of the organic binder in just a few minutes. The technique wasapplied to the identification of indigo in a blue sample from a mural painting dated from the 18th century andhoused in an Andean church in Bolivia. At the same time, the acquired data revealed for the first time the useof an egg tempera binding medium in an Andean mural painting