An open, non-contact cell for laser ablation-inductively coupled plasma-mass spectrometry

Abstract

A novel, open, non-contact cell for laser ablation, capable of sampling: large planar samples, embedded planar samples, or samples of less than 2 mm mounted on a planar platform, without an outer containment enclosure, is described. This cell, when tested on NIST-613 CRM, exhibited rapid wash-out (<3.6 s for 99% signal reduction), low limits of detection and good signal precision in LA-ICP-MS. The cell uses a dual, annular, micro-jet gas flow array to exclude atmospheric gases and to entrain the ablated sample aerosol. The micro-jet array employed enabled a sampling height, between the sample surface and the lowest plane of the cell, of up to 200 µm. The micro-jet array has the facility to be electrically biased if the application demands it, e.g. extracting a charged plume in Matrix-Assisted Laser Desorption/Ionisation (MALDI) or Desorption Electrospray Ionisation (DESI) experiments. This particular implementation of the cell featured dual sample output channels, which could enable connection of the cell to more than one analyser. A micro jet-pump was coupled to the cell to extract the ablated aerosol from the low-volume inner ablation chamber, provide mixing of the aerosol with the injector flow of the ICP and to isolate the cell from downstream conditions in the injector flow. Potential applications of this cell include: analysis of silicon wafers, gel-plates/membranes, tissue samples, multiple sample analysis in high throughput facilities; and toxic fume removal and analysis in laser scribing, cutting and etching.