A Novel Conjugated Octupole-Quadrupole Ion Guide Achieving High Transmission

Area of Science:

• Analytical Chemistry
• Mass Spectrometry Instrumentation

Background:

• High ion transmission efficiency is essential for mass spectrometer sensitivity.
• Current ion guides face challenges in maintaining efficiency from atmospheric pressure to vacuum.

Purpose of the Study:

• To develop and evaluate a novel conjugated octupole-quadrupole ion guide, termed the 8-4 pole ion guide.
• To assess the impact of the 8-4 pole ion guide on mass spectrometer sensitivity and ion transmission efficiency.

Main Methods:

• Measured signal intensity dependence on DC/RF voltages and pressure within the 8-4 pole ion guide.
• Estimated transmission efficiency via ion current measurements before and after the guide.
• Evaluated mass spectrometer sensitivity using testosterone analysis and employed simulations for ion behavior analysis.

Main Results:

• The 8-4 pole ion guide demonstrated high transmission efficiency (56%) within a pressure range of 100-200 Pa.
• Achieved a 56% ion transmission efficiency with 1.0 nA ion current throughput.
• Mass spectrometer equipped with the 8-4 pole ion guide showed a 2.9% CV for 1 pg/mL testosterone and a 0.12 pg/mL limit of detection.

Conclusions:

• Successfully developed a novel 8-4 pole ion guide with high ion transmission efficiency.
• The enhanced sensitivity of the mass spectrometer confirms the ion guide's effectiveness.
• The 8-4 pole ion guide maintains high efficiency even with high gas flow rates (5 L/min).