Identification of α-phase crystallization Pigment Red 254 in artist's paints by powder x-ray diffraction

Abstract

Diketopyrrolopyrrole (DPP) is a pigment widely used in modern paints for industrial and artistic applications. Identification of this pigment in paint for art authentication and forensics has previously been accomplished with gas chromatography/mass spectrometry or Laser Raman. Three commercial artist's paints containing DPP were analyzed by x-ray diffraction (XRD). Alpha phase DPP was identified in two of the samples, barite extender the only crystalline component identified in the other sample. In conclusion, XRD analysis of paint samples can identify DPP, as can other organic analyses, but has the advantage of being non-destructive and also identifying the crystal structure. However, the fact that in one sample only extender could be identified does impose some limitations on the analysis of paints.