Structural elucidation is a common challenge when working with unknown or degraded samples. Anthraquinones are a type of aromatic compound with keto groups on the 9, 10 positions of the central ring. These molecules can have one or more identical or similar functional groups substituted on different locations of the anthraquinone rings. This can make structural elucidation difficult when comparing similar compounds and mixtures.

Anthraquinone dyes are a type of commercial disperse textile dye used to dye polyester fibers. Commercial dyes are often mixtures of multiple dyes and as environmental regulations increase, the corresponding rise in manufacturing cost is driving dyestuff manufacturers to develop new alternatives. It is therefore important to develop a database to aid in the structural elucidation of these small aromatic systems.

Twenty anthraquinone dyes were selected from the Max Weaver Dye Library, a unique collection of approximately 100,000 novel synthetic dyes at NC State. These dyes contained different combinations of amino, sulfamide, sulfone, thioether, halogen, aromatic, aliphatic amine, and thioether functional groups on the 1, 2, and 4 positions of the anthraquinone ring. Due to the historic nature of these dyes, mass spectrometry (MS) and tandem mass spectrometry (MS²) was used for this study. The Max Weaver dyes were characterized and fragmented using a quadrupole time-of-flight (QTOF) mass spectrometer equipped with electrospray ionization (ESI) for MS and MS² spectral acquisition. Observed fragments of each dye were used to create a database containing different functionalities and their corresponding fragments. Because the QTOF mass spectrometer is only capable of MS², the same dyes were then fragmented on a quadrupole linear ion trap (LTQ) mass spectrometer to obtain MS³ or higher spectra. This information is being added to the database to obtain a further in-depth understanding of how different functionalities on anthraquinone compounds affect fragmentation. The continued growth of this database will create the ability to identify unknown anthraquinones using tandem mass spectrometry.

Nelson Vinueza

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