Reducing blockages, cross-contamination, and flow instability in ICP sample introduction systems

The Guardian™ Autosampler Probe from Glass Expansion is designed to improve stability in ICP-OES and ICP-MS sample introduction by addressing three recurring operational issues: blockage formation, cross-contamination, and inconsistent sample uptake. The design focuses on maintaining a steady and reproducible flow path from sample vial to nebuliser under a wide range of matrix conditions.

Unlike conventional autosampler probes that rely on an open sample uptake pathway, the Guardian Probe uses a cone-shaped ceramic tip with a microhole-based protective geometry. These micro-scale openings are not designed to operate as a conventional filter with a defined pore size requiring routine cleaning. Instead, they act as a physical barrier that limits the ingress of larger particulates while maintaining continuous sample flow. 

Blockage prevention and flow stability

A key advantage of this approach is that it reduces the risk of abrupt flow interruption caused by particulate ingress. Larger particles are less likely to pass through the ceramic tip structure, while smaller particles continue through the system with minimal disruption to flow dynamics. This supports more stable uptake performance across aqueous, organic, and higher-viscosity matrices.

Standard PTFE-sheathed carbon fibre probes typically use a fixed sample line integrated into the probe body. If a blockage occurs anywhere along this line, the entire probe assembly generally requires replacement. The Guardian™ Probe separates the sample line from the probe body through interchangeable UniFit™ tubing, meaning that in the event of a blockage, only the sample line needs to be replaced. This reduces downtime and simplifies maintenance without requiring full probe replacement. 

Cross-contamination control and sample integrity

Cross-contamination is reduced through the novel cone-shaped tip design, which incorporates a combination of controlled particle filtering and minimised droplet retention. Moreover, the umbrella-shaped baffle effectively captures any residual sample running down the probe's length, ensuring cleanliness as it moves across other sample vials.

Performance validation in aqueous systems

Independent aqueous testing in aqueous matrices (2% HNO₃ with tracer dye) shows stable uptake behaviour with reduced droplet formation and improved consistency between sampling cycles compared with standard probe designs.

The Guardian Probe is designed for direct installation on major ICP autosampler platforms (Cetac, Agilent^®, PerkinElmer^®, Shimadzu^®, Aim Lab, and Thermo Fisher Scientific™ Autosamplers), without modification, supporting rapid replacement and consistent sample handling across laboratories. Further technical documentation provides detailed configuration guidance, including sample line selection, flow optimisation, and compatibility across major ICP autosampler platforms: 

Additional protection: Guardian™ in-line filter (120 µm)

For applications requiring further particulate control, the Guardian™ in-line filter (120 µm) can be integrated upstream of the sample path for demanding sample environments. This combination is intended to address both sudden blockage events and longer-term accumulation effects within sample introduction systems.