Identification of Chrome Pigments in Paints with Fourier Transform Infrared Spectroscopy (FTIR), Confocal Raman Microscopy, and Scanning Electron Microscope-Energy Dispersive Spectrometer

Although many countries have banned the application of chrome pigments in coatings, these pigments and the products involving them are still widely used. Due to the high toxicity of chromium (Cr) to human beings and ecosystems, its identification is necessary. For forensic scientists, it is of great help to look for clues when treating hit-and-run cases. In this study, a method based on the combination of Fourier transform infrared microscope, confocal Raman microscopy, and scanning electron microscope-energy dispersive spectrometery are performed to identify the chrome pigments. The characteristic peaks of 857cm(-1), 628cm(-1), and 610cm(-1)in Fourier transform infrared spectroscopy, the characteristic peaks of 125cm(-1), 357cm(-1), and 840cm(-1)in Raman and the intense peaks of Pb (10.550keV) and Cr (0.573keV) in scanning electron microscope-energy dispersive spectrometry (SEM-EDS) could all be directly used to identify the existence of chrome pigments. The analysis results of the samples randomly chosen demonstrated that the combination of the three data can further verify each other's results and then provide more reliable information on the chrome pigments.