Acoustically Levitated Sample Introduction for GC–MS: A Novel Contactless Approach to Direct Volatile Analysis

Abstract

Conventional GC–MS sample introduction methods often involve physical contact, increasing contamination risk and analyte degradation, especially in sensitive matrices. This study introduces a novel, contactless interface using standing-wave acoustic levitation to suspend analytes in mid-air prior to GC–MS analysis. A 28 kHz ultrasonic transducer, powered by a high-voltage amplifier, generates stable levitation nodes inside a custom chamber, enabling droplets and solid particles to remain airborne during volatilization. Volatile analytes are transferred via heated gas mixture directly into the GC inlet. Acetone droplets yielded strong, reproducible m/z 58 ion signals, and real samples like cucumber (Cucumis sativus) skin demonstrated broader applicability. Helium–nitrogen gas mixture was optimized for both levitation stability and ionization efficiency. The system minimized surface contact, preserved sample morphology, and reduced cross-contamination risks. This platform establishes acoustic levitation as a viable sample delivery strategy for GC–MS, offering enhanced cleanliness, reduced sample loss, and novel handling of delicate or trace-level materials. It opens new directions for automation and integration in analytical workflows.