Cleaning the 5000 Series ICP-OES Torch, Acid and Aqueous Matrices

Answer

This Information Applies To: Agilent 5000 Series ICP-OES (5100/5110/5800/5900)

Issue

The ICP-OES torch plasma ionizes the introduced gas or aerosol stream. In normal operating conditions, incomplete ionization occurs and material is deposited on the torch surface. Build up of deposits can create blockages, damage the torch or interact with the sample stream causing poor precision, accuracy, and memory effects. 

ICP-OES overview

The ICP-OES sample introduction components are detailed in Figure 1.

Figure 1: ICP-OES sample introduction components

1. Torch loader handle   2. Torch   3.Torch clamp   4. Nebulizer gas connections   5. Spray chamber drain tubing   6. Spray chamber   7. Nebulizer   8. Nebulizer inlet tubing

Caution: The torch is fragile. Do not use cleaning wire or abrasives like brushes or a scourer to clean the torch. Avoid acid contact with the seal where the quartz meets the plastic base. Damage to the seals and torch body may occur.

Removing the torch

1. Turn off the plasma and allow instrument to cool.

   Caution: The torch and torch compartment become hot during instrument operation and remain so for some time after the plasma has been switched off. Allow the plasma compartment to cool before accessing the compartment. Allow the torch to cool before touching the outer tube or attempting to dismantle the torch.

2. Disconnect the spray chamber (Figure 1).

3. Remove the torch from the instrument.

4. Disassemble fully and semi-demountable torches.

   Tip: See page 34 of the Agilent ICP-OES User's Guide for demountable torch disassembly instructions.

   
   

   Fully demountable torch

   

   Semi-demountable torch

5. Inspect the torch components for damage including holes or cracks in the plastic housing, seal or glass tubing, and the outer quartz tube becoming rough to touch. Discoloration of the plastic housing occurs with long-term exposure to acid and does not impact on performance. Replace as necessary.

Cleaning the torch

1. Prepare a 50% aqua regia solution (one-part de-ionized water to one-part aqua regia) in a wide diameter beaker. To make Aqua Regia, combine 1:3 concentrated nitric acid: hydrochloric acid.

   Warning: Nitric, hydrochloric, and aqua regia are corrosive and can cause severe burns when they come into contact with skin. Wear Personal Protective Equipment when handling acids.

2. Pipette aqua regia through the ball joint of the injector to remove build-up from the lower part of the injector.  Do not let the acid contact the seal between the quartz outer tube and the plastic base.

    

3. Place the beaker containing the acid solution under the ICP-OES Easy-fit torch stand (part number G8010-68021) and place the torch and components in the acid. The Easy-fit torch stand prevents damage to the fragile end of the quartz outer tube and limits exposure of the torch body to acid fumes, reducing premature degradation. Ensure that:

   1. The tube set and injector are immersed.

   2. The acid level is just below the plastic base, and not in contact with the seal between the quartz and the plastic base.

   3. Keep the torch vertical, with the ball joint at the top.

   4. Do not soak the removable top seal of semi-demountable torch.

   5. Do not remove the torch adhesive cap on the one-piece torch that covers the seal between the quartz and the plastic.

      Caution: Do not use a cleaning wire or other abrasives (i.e. brushes, scrub, or a scourer) to clean the torch. Avoid acid contact with the seal where the quartz meets the plastic base. Damage to the seals and torch body may occur.

        

      A. Torch B. and C. Semi-demountable torch D. ICP-OES Easy-fit torch holder

4. Soak for at least one hour and no more than four hours.

5. If deposits remain after using 50% Aqua Regia, repeat the cleaning process using a higher concentration of Aqua Regia.

Rinsing the torch

1. Hold the torch with the ball joint connector at the top and thoroughly rinse the outside, inside through ball joint connector, upper and lower gas ports. Rinse the removable top seal on semi-demountable torches. 

   

Drying the torch

1. Flush all torch components with laboratory grade compressed air or nitrogen. Flush the torch through the gas supply ports and the ball joint connector, then invert and flush through the open end of the quartz outer tube set. Do not insert the air/nitrogen nozzle inside the tube set. When flushing is not available, dry glass components in a drying oven and plastic components with a lint free cloth. 

2. Ensure that all moisture is removed then re-assemble and refit the torch.

3. When not is use, store the torch in the original packaging or the ICP-OES Easy-fit torch storage rack (part number G8010-67000).

Additional Checks after cleaning 

1. When reassembling and refitting the torch, inspect for damage such as loose fitting of the quartz tubes in the plastic base, rough outer surface of the quartz tube or any visible cracks or holes. If any damage is found, replace the torch immediately.

2. Check for carry-over after refitting the torch to determine if the cleaning procedure has been sufficient. If carry-over is found, repeat the cleaning process.

Recommended maintenance: Agilent recommends daily inspection and weekly cleaning of the torch. Analysis of samples with complex matrices may require more frequent cleaning.

Learn how to effectively maintain your Agilent ICP-OES:  ICPOES-5110-1270e, Agilent 5110 ICP-OES Maintenance and Troubleshooting e-learning course available from Agilent education