Surface acoustic wave nebulization device with dual interdigitated transducers improves SAWN-MS performance

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Surface Acoustic Wave Technology

Background:

• Surface acoustic wave nebulization (SAWN) is a key technique for sample introduction in mass spectrometry (MS).
• Optimizing droplet size and desolvation efficiency is crucial for improving MS performance.

Purpose of the Study:

• To compare the MS performance of a progressive wave (PW) SAWN device with a single interdigitated transducer (IDT) against a standing wave (SW) SAWN device utilizing a dual IDT.
• To investigate the impact of droplet size and ion flux on MS signal/noise ratio.

Main Methods:

• Fabrication and testing of single IDT (PW-SAWN) and dual IDT (SW-SAWN) devices.
• Mass spectrometric analysis of peptide samples.
• High-speed imaging and phase Doppler particle analysis to characterize droplet size distribution and plume dynamics.

Main Results:

• The SW-SAWN chip demonstrated a 100-fold improvement in the limit of detection (1 femtomole of peptide).
• A 26% increase in small droplet production (1-10 µm) was observed with the SW-SAWN device.
• The dual IDT design generated a more instantaneous plume, leading to higher ion flux into the mass spectrometer.
• Improved protein mass spectra quality up to 20 kDa was achieved with the dual IDT device.

Conclusions:

• The dual IDT SW-SAWN design significantly enhances MS sensitivity and spectral quality compared to the single IDT PW-SAWN design.
• The primary driver for improved MS performance is likely the increased ion flux resulting from the dual IDT's plume characteristics.
• This technology offers a substantial advancement for sensitive protein analysis via mass spectrometry.