ICP Torches and Injectors: Bore Size, Demountable vs One-Piece, and When to Replace

An ICP torch is a consumable that most labs treat as a fixture until it cracks mid-run. At LabSupplies.com, the torch questions that reach us split evenly between “which injector bore do I need” and “why did this one go cloudy” — and the two are related, because the wrong bore for your matrix is one of the things that puts deposits where devitrification starts. The three decisions are geometry, injector bore, and whether you buy the torch as one piece or as parts you can replace individually.

Geometry Is Not a Preference

Axial, radial and dual-view torches are not interchangeable — the viewing geometry is set by the instrument, and the same part is often listed in both a plain and a with-fittings version. Get this wrong and nothing else about the order matters. Alpha Resources lists them explicitly: axial with a 2.5 mm injector, dual view with the same bore, and radial demountable with fittings, among many others.

Injector Bore: the Decision That Follows the Matrix

Bore	Aerosol behaviour	Suits
1.0 mm	Highest velocity, finest delivery	Clean aqueous samples, best detection limits
1.5 mm	General-purpose compromise	Routine aqueous and light digests
2.0 mm	More aerosol, lower velocity	Heavier matrices, some organics
2.5 mm	Highest tolerance for deposits	Organic solvents and high dissolved solids

The trade is the same one that governs nebulizer choice: narrow gives sensitivity, wide survives the matrix. An organics method run on a narrow injector builds carbon at the tip; a clean aqueous method on a wide injector simply reads lower than it should. Alpha lists dedicated one-piece torches for organics alongside the aqueous equivalents, and a bare quartz injector as a replaceable part.

If you have not read it, the companion decision sits upstream: our ICP nebulizer and spray chamber guide covers matching the nebulizer and chamber to the same matrix. Torch, injector, chamber and nebulizer are one system; changing one and not the others is how a method quietly stops working.

Demountable or One-Piece

A demountable torch comes apart, which changes the economics twice over. When the injector devitrifies you replace the injector, not the torch. When the method changes you swap bore size instead of buying a second complete torch. The cost is joints — more places to leak, more to align, more to get wrong on reassembly.

A one-piece torch removes those failure modes and adds a bigger bill when any part of it fails. Some instruments and methods specify one or the other outright; where you have a genuine choice, a lab that runs one stable method is usually better off one-piece, and a lab that runs mixed matrices is usually better off demountable. Separate torch bodies are stocked for exactly that reason.

Devitrification: What Kills Torches

Quartz under sustained plasma heat can lose its glassy structure and crystallise. It shows as a white or frosted patch, almost always near the tip. Devitrified quartz is mechanically weak, and it cracks — usually at the least convenient moment.

What accelerates it:

• Salt and alkali deposits. High-solids matrices left to bake on rather than cleaned off between runs.
• Fingerprints. Skin oils bake into the surface and seed crystallisation. Gloves, always, even for a quick reseat.
• Scratches. Scrubbing a deposit off scores the quartz and gives crystallisation somewhere to start. Soak instead.
• An injector bore fighting the matrix. Deposits form fastest where the aerosol is not moving the way it should.

Once frosting is visible, the torch is on borrowed time. Order the replacement then, rather than discovering it during a run that has a deadline attached.

The Parts People Forget

A torch order is rarely just a torch. Torch bonnets, torch shields and the argon hose and fitting all wear or get damaged on removal, and a with-fittings version of a torch costs more than the plain one because those fittings are included. Check what your instrument needs before deciding the plain listing is the cheaper option — it frequently is not.

Ordering Against an OEM Part Number

Most of this range carries an OEM cross-reference in the listing title — Teledyne Leeman, Thermo Fisher Scientific, PerkinElmer and Agilent numbers among them. If your manual gives you a part number, search that number rather than a description. Then confirm three things: the viewing geometry, the injector bore, and whether the version you are looking at includes fittings. A part number alone has never been a safe match on its own.

Browse ICP torches, cones and injectors, or the wider Alpha Resources range for nebulizers, spray chambers and analyzer consumables.

Frequently Asked Questions

What injector bore size should I use?

Narrow bores such as 1.0 and 1.5 mm raise aerosol velocity and suit clean aqueous samples and the best detection limits. Wider bores such as 2.0 and 2.5 mm move more aerosol at lower velocity, which is what organic solvents and higher-solids matrices need to avoid carbon or salt building up at the injector tip. Start from your instrument manual and your matrix, not from a preference for sensitivity.

Is a demountable torch better than a one-piece torch?

It is cheaper to run and more flexible. A demountable torch lets you replace only the injector or only the outer tube when one fails, and lets you change injector bore for a different matrix without buying a whole torch. A one-piece torch has no joints to leak or misalign, which some methods and instruments prefer. Both are stocked; the instrument usually decides.

What is devitrification and how do I spot it?

Devitrification is quartz losing its glassy structure and crystallising, and it shows as a white, cloudy or frosted patch, usually near the tip where the plasma sits. It is driven by salt deposits, alkali metals and contamination such as fingerprints. A devitrified area is mechanically weak and will eventually crack. Once it is visible, plan the replacement rather than waiting for the failure.

Do axial, radial and dual-view torches interchange?

No. The viewing geometry is set by the instrument, and the torch has to match it. Axial, radial and dual-view torches are listed separately, sometimes in both plain and with-fittings versions of the same part. Match the geometry first, then the injector bore, then the fitting style.

How should I clean an ICP torch?

Handle it with gloves, never bare hands, because skin oils bake into the quartz and seed devitrification. Soak rather than scrub: an appropriate acid soak lifts deposits without scoring the surface, and a scratched torch fails sooner. Rinse thoroughly with high-purity water and let it dry completely before the plasma sees it.

Setting up a new lab? Our LaunchLab program gives you 15% off everything for 12 months, ICP consumables included. See if you qualify →

Have the OEM part number? Search it directly at LabSupplies.com, or browse the torch range. Browse the collection →

Send us the instrument model and the OEM number at support@labsupplies.com and we will confirm geometry, bore and fittings before you order.

Related Guides

• ICP Nebulizers and Spray Chambers
• Crucible Selection for Carbon and Sulfur Analyzers
• Tin vs Silver Capsules for CHNS Elemental Analysis
• Certified Reference Materials for Combustion Analysis
• Lab PPE Requirements Guide

Sources and Technical References

• NIST Standard Reference Materials — nist.gov
• 40 CFR Part 136 — Guidelines Establishing Test Procedures for the Analysis of Pollutants — ecfr.gov

— By the LabSupplies.com Technical Team