Fading of colorants by atmospheric pollutants: mass spectrometry studies

• Published in: The Science of the total environment Vol. 152; no. 2; pp. 125 - 134
• Main Authors: Grosjean, Daniel, Sensharma, Dilip K., Cass, Glen R.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier B.V 02.08.1994; Elsevier Science
• Subjects: Air pollution damage to colorants; Applied sciences; Art conservation; Artists' colorants; Atmospheric pollution; Exact sciences and technology; Mass spectrometry; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Artists' colorants; Air pollution damage to colorants; Mass spectrometry; Art conservation; Discoloration; Indigoid dye; Cultural artefact; Nitrogen heterocycle; Anthraquinone dye; Ozone; Tricyclic compound; Chemical ionization; Unsaturated compound; Sulfur heterocycle; Bicyclic compound; Reaction mechanism; Air pollution; Curcumin; Oxidation
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/0048-9697(94)90492-8

Chemical ionization mass spectra have been recorded for a number of artists' colorants that fade rapidly when exposed to atmospheric levels of ozone and other photochemical air pollutants. These colorants include the natural colorant curcumin, several indigos and a number of alizarin derivatives. Also included are isatins, which are produced in the fading of indigo colorants by atmospheric pollutants. The protonated molecular ion MH (M = compound mol. wt.) was the most abundant peak in the methane chemical ionization spectra of most of the artists' colorants studied. Other peaks that are of important diagnostic value are discussed for each category of colorant. Examples of applications are included and illustrate the usefulness of chemical ionization mass spectrometry in assessing air pollutant-induced damage to paintings and other colorant-containing objects of artistic and historical value.