PB 24 – erioglaucine

It is one of the oldest FDA-approved color additives for food. In art supplies it is found in felt-tip pencils

Manufacturer/ product code:  GTI laboratories supplies / erythrosine B
Chemical Description:  triarylmethane dye, C37H34N2Na2O9S3, CAS 3844-45-9, C.I. 42090. food coloring E133, brilliant blue FCF
Color: blue
Color Index: PB 24
More info:  wikipedia

“Handheld surface-enhanced Raman scattering identification of dye chemical
composition in felt-tip pen drawings” J Raman Spectrosc. 2018;1–10.