The ELVIS Probe: Combining Laser Pointer Desorption, Venturi-Assisted Plume Transport, and Electrospray Ionization in a Simple Handheld Tool for Remote Ambient Mass Spectrometry

Abstract

Here we introduce the Electrospray Laser Venturi Ionization Sampling (ELVIS) probe, a handheld ambient sampling device that combines desorption performed by a simple laser pointer with Venturi-assisted plume transport for remote mass spectrometric analysis. The ELVIS probe is portable, inexpensive, easy to operate and to point to a target area and exhibits no detectable carryovers. The probe can also be readily coupled to most atmospheric-pressure ionization sources, as demonstrated herein for electrospray ionization (ESI). The ELVIS probe employs Venturi pumping to provide efficient and controllable aspiration of the laser-generated plume. This mechanism transports analyte vapors directly to the ion source, substantially reducing signal dispersion that commonly occurs during open-air sampling or when carrier gases are used. Desorption is achieved using a compact, low-cost, yet highly effective 0.5 W laser pointer, enabling the sampling of a wide range of analytes from diverse matrices. Notably, the ELVIS probe is particularly advantageous for sampling target analytes deeply embedded within complex matrices, where spray-based or liquid-extraction ambient MS techniques often fail. For proper ionization, the probe was coupled to a commercial ESI source and successfully applied to the detection of illicit drugs, plasticizers in PVC, caffeine directly from a coffee bean, and pesticide residues on the wings of a deceased honeybee. The advantageous coupling of the ELVIS probe with Venturi-assisted easy ambient sonic-spray ionization is also discussed.