A precise self-built secondary mass database for identifying red dyes and dyeing techniques with UPLC-MS/MS

Area of Science:

• Scientific analysis of historical textiles
• Natural dye chemistry and analysis
• Conservation science

Background:

• Dye analysis on ancient silks is crucial for historical understanding and restoration.
• Existing methods often overlook the link between natural dye origins and color degradation, hindering accurate silk restoration.
• A comprehensive database for natural red dyes is needed.

Purpose of the Study:

• To develop a precise tandem mass spectrometry (MS/MS) database for identifying natural red dyes on historical silks.
• To investigate the relationship between natural dye origins and color reduction methods.
• To enable accurate identification and restoration of ancient silk artifacts.

Main Methods:

• Preparation of 12 red hue silk samples using six natural dyes and three dyeing techniques.
• Extraction of dye compounds using organic solvents.
• Analysis using ultra-performance liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS).
• Establishment of a preliminary and a secondary MS/MS database with targeted MS/MS mode.

Main Results:

• A self-built secondary MS/MS database containing 33 compounds, 32 chromatograms, and 32 MS/MS fragments was successfully established.
• The database identified Chinese madder as the dye on two historical silk samples from the Shanghai Museum, with variations in mordant dyeing order.
• Experimental restoration achieved visually indistinguishable results (ΔEab < 1.5 NBS).

Conclusions:

• The developed precise MS/MS database is effective for identifying natural dyes on historical silks.
• This methodology provides a foundation for tracing biological dyestuffs and aids in the protection and restoration of cultural heritage.
• The study bridges archaeological science and art conservation through advanced analytical techniques.