Evaluation of Oblique Light-Induced Degradation of Indoor Line Tape by Mass Spectrometry (2): Qualitative Analysis of Orange Pigment Components
MSTips No. 531
Indoor line tapes have a multilayer structure composed of multiple materials to ensure visibility and durability, and understanding the material composition of each layer is important from the perspectives of quality evaluation and material design. In the previous report, among the three-layer structure of the indoor line tape shown in Figure 1, the base material layer and the adhesive layer were examined, and the results of compositional estimation using the direct EGA-MS method were presented. In the present study, following this work, an attempt was made to estimate the composition of pigments contained in the pigmented layer. In addition, a comparison was conducted with a tape that had been applied for eight months and exhibited whitening of the colored surface under oblique light.
Pigments are used in a dispersed state as solid particles during processes such as printing. Owing to their chemical structure, they possess crystalline structures and strong intermolecular interactions. Consequently, they exhibit low solubility in water and common organic solvents, as well as low volatility. As a result, qualitative analysis of pigments themselves by mass spectrometry coupled with chromatography is generally considered difficult.
DEP (Direct Exposure Probe) is a technique in which a sample is directly applied to a platinum filament at the tip of the probe and rapidly heated by applying an electric current to the filament. This method enables rapid ionization while minimizing thermal decomposition of the sample, thus requiring little to no complex sample pretreatment and making it suitable for the analysis of nonvolatile substances or those prone to thermal decomposition.
In this study, therefore, a direct introduction method using DEP was applied, and the results of rapid qualitative analysis of organic pigments contained in the pigmented layer of an indoor line tape are reported.