It’s vital not to overlook the importance of sample introduction in ICP-MS applications
Inductively coupled plasma mass spectrometry (ICP-MS) achieves detection limits from the part-per-billion to part-per-trillion levels using an elaborate system of pumps, sprays, filters, and torches to transform liquid samples into charged ions.
According to Gareth Pearson, ICP-MS Supplies Product Manager at Agilent, most ICP-MS troubleshooting stems from the sample introduction system. Pearson has developed a series of ICP-MS video tutorials that teach fundamental principles while providing insider tips. The first tutorial in his series focuses on ICP-MS sample introduction — the central learning points are summarized below.
Key steps in ICP-MS sample introduction
The first step in ICP-MS sample introduction involves peristaltic pumps, which rely on specialized, chemical-compatible tubing to regulate flow rate. Because so much liquid needs to drain from both the sample chamber and other parts of the instrument, Pearson emphasizes that users need to plan for higher-than-anticipated drainage — miscalculations could be disastrous.
Next, nebulizers force the liquid through narrow capillaries to produce aerosols with droplet sizes below 10 microns. Thinner capillaries lead to higher ICP-MS analysis sensitivity, but this comes at the price of increased blockages, another troubleshooting hot-spot.
Bouncing the aerosol through vortex-inducing spray chambers ensures that only the finest droplets can enter the plasma torch, where they become ionized. Pearson notes that only Agilent torches have shields in place to reduce interference with the plasma gas and background noise, helping their instruments achieve ultra-low detection limits.
Finally, analyte ions pass through a series of skimmer cones and ion lenses which focus the charged particles into the mass spectrometer for detection.
The importance of cleanliness in ICP-MS sample introduction
According to Pearson, the most common ICP-MS sample introduction problems include:
- Worn tubing
- Nebulizer damage
- Dirty spray chambers
- Poorly aligned torches
- Blocked or damaged skimmer cones
Fortunately, these issues are most often solved through regular cleaning. But there’s a catch — each element of an ICP-MS sample introduction system has specific cleaning needs.
For example, nebulizers should never be sonicated as their capillaries are far too fragile. Sampler and skimmer cones that protect the plasma torch, however, regularly see the inside of a sonication chamber to remove impurities from their metal surfaces.
Further key ICP-MS considerations
Ready to progress beyond sample introduction? In subsequent tutorials, Pearson covers a range of additional ICP-MS topics, including:
- Sample preparation: Learn about the differences between working with water and organic solvents, samples with high levels of total dissolved solids (TDS), and when to unleash one of the most powerful tools in a chemist’s toolkit — hydrofluoric acid.
- ICP-MS speciation: Now that you’ve successfully transformed your sample into the ionized state, how do you quantify the elements present? Pearson and guest Jenny Nelson provide an in-depth look at ICP-MS speciation in both liquid- and gas-phase applications.
- Laser ablation (LA) ICP-MS: This technology has the potential to revolutionize fields like forensics because it can analyze the thin upper layer of solids. Learn the right hardware and software setup to perform precision elemental and isotope analysis with this technique.
These tutorials are presented by Gareth Pearson (ICP-MS Supplies Product Manager at Agilent). Gareth graduated from the University of Hull, UK in 2003 with a M.Chem. in Chemistry with Analytical Chemistry & Toxicology. He went on to complete a Ph.D. using ICP-MS in 2007 with the title “Elemental Speciation and Miniaturised Sample Introduction Studies for ICP-MS”. He has worked as a Product Manager in the UK and Australia for Spectroscopy and Sample Preparation instrumentation since 2007. Currently, Dr. Pearson is the ICP-MS Spectroscopy Supplies Product Manager for Agilent based at the Spectroscopy Technology Innovation Centre in Melbourne, Australia. He has over 15 years’ experience in Analytical Chemistry and Spectroscopy.
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