Analysis of organic EL material by JMS-T100GC “AccuTOF GC” - comparison of FD and DEI methods

Importance of the Topic

Organic electroluminescent materials play a vital role in modern display and lighting technologies. Reliable characterization of their molecular structure and formula is essential for material development, quality control, and performance optimization.

Objectives and Study Overview

This application note presents a comparative analysis of field desorption (FD) and desorption electron ionization (DEI) for the mass spectrometric examination of 4,4’-Bis(2,2-diphenyl-ethen-1-yl)biphenyl (DPVBi) using the JMS-T100GC AccuTOF GC platform.

Methodology and Instrumentation

Field Desorption (FD)

• Cathode potential: −10 kV
• Emitter current ramp: 0 to 40 mA at 51.2 mA/min

Desorption Electron Ionization (DEI)

• Electron ionization: 70 eV, 300 κ filament current
• Desorption energy program: 0 to 1.0 A at 5.12 A/min

Instrument and Acquisition Parameters

• System: JEOL JMS-T100GC AccuTOF GC
• Mass range: m/z 35–600
• Spectral interval: 0.5 s

Results and Discussion

DEI spectra exhibited numerous fragment ions in addition to the molecular ion, complicating straightforward mass assignment. In contrast, FD spectra were dominated by the intact molecular ion, facilitating unambiguous molecular weight determination. Accurate mass measurement under FD conditions yielded 510.23378 Da (calculated 510.23475 Da; mass error –0.97 mmu), confirming the formula C40H30 and an unsaturation index of 26.

Benefits and Practical Applications

The FD approach offers soft ionization that preserves the intact molecular ion, enabling direct formula elucidation without extensive fragmentation. Coupled with high-resolution TOF detection, this method is highly suited for nonvolatile organic compounds, polymers, and advanced electroluminescent materials, streamlining analytical workflows in research and QA/QC laboratories.

Future Trends and Possibilities

Potential developments include integration of FD-TOF MS with chromatographic separation for enhanced compound profiling, automation for high-throughput screening of OLED and optoelectronic materials, and novel emitter technologies to further improve ionization efficiency and mass accuracy.

Conclusion

Comparative evaluation demonstrates that FD combined with AccuTOF GC provides superior clarity of molecular ion signals and accurate mass data for organic EL material analysis, outperforming DEI for precise formula confirmation.

Reference

JEOL MS Data Sheet No 040/078 JEOL Ltd 2006