Spatially resolved analysis of liquid crystal displays by laser ablation-atmospheric pressure chemical ionization-mass spectrometry

• Published in: Analytica chimica acta 2019-05, Vol.1055, p.56-64
• Main Authors: Müller, Jennifer-Christin, Berg, Tanja, Enders, Claudia, Leonhard, Peter, Karst, Uwe
• Format: Article
• Language: English
• Subjects: Atmospheric pressure; Atmospheric pressure chemical ionization-mass spectrometry (APCI-MS); Crystal defects; Crystals; Ionization; Ions; Laser ablation; Laser ablation (LA); LCDs; Liquid crystal display (LCD); Liquid crystal displays; Mass spectrometry; Mass spectroscopy; Organic chemistry; Principal components analysis; Principle component analysis (PCA); Sample preparation; Scientific imaging; Sealing compounds; Spectroscopy
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2018.12.048

In recent years, liquid crystal displays (LCDs) became more and more popular in industrial and consumer electronics applications. Unevenly distributed liquid crystals (LC) and the presence of organic contaminations in the LC layer, for example from the display sealant, can cause display defects and therefore lower the display quality. This work describes the development of a fast and easy screening method for display samples by laser ablation coupled to atmospheric pressure chemical ionization-mass spectrometry (LA-APCI-MS). With this ambient technique, LC components as well as sealant materials, which are one of the main sources for display contaminations, can be detected simultaneously using spatial resolutions down to 100 μm. Minimal sample preparation is needed for this method and exact masses can be acquired by using an Orbitrap mass analyzer. By LA-APCI-MS, nineteen different LCs and five different sealant materials were detected as pure substances as well as on commercially available LCDs. In addition, a principle component analysis (PCA) was used to differentiate between LCs and sealant ions in the complex data matrix. [Display omitted] •Liquid crystal displays were analyzed with laser ablation APCI-MS.•Sealants and liquid crystals were differentiated using principle component analysis.•Spatially resolved results with minimal sample preparation and exact masses were acquired.