Cleaning the ICP-OES Nebulizer

Answer

This Information Applies To: Agilent 500 Series ICP-OES (5100, 5110, 5800, 5900)

Issue

The ICP-OES nebulizer converts the liquid sample into an aerosol as it enters the spray chamber. A dirty or partially blocked nebulizer traps sample, which leads to poor reproducibility and reduced sensitivity. Droplets on the internal surface of the spray chamber can indicate poor conversion of liquid to mist.

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

Tips: Not all nebulizers are the same, and fittinmgs will vary with the nebulizer.

Blocked nebulizer

A blocked nebulizer can be identified by a visual inspection as per Figure 2. 

Figure 2: Blocked nebulizer
1. Blockage at tip 2. Sample trapped in the nebulizer tip

Steps to follow

Caution: The concentric glass nebulizer is fragile. Handle with care. Do not place a glass nebulizer in an ultrasonic bath as vibrations may cause edge chipping or cracking and degrade the performance of the nebulizer. Do not use hydrofluoric acid with glass or quartz sample introduction components.

1. Turn off the pump and the plasma. Remove the nebulizer, being careful not to touch the tip of the nebulizer.

    

2. Different cleaning solutions can be used to clean the nebulizer including 2.5% detergent solution, methanol, or 10% nitric acid. Flush the nebulizer with the selected cleaning solution in both directions:

   1.  Push liquid through using a syringe attached with a small piece of soft plastic tubing or the nebulizer cleaning tool (part number G3266-80020). This tool is suitable for concentric nebulizers. It cannot be used with the Agilent OneNeb nebulizer as it differs in construction. 

      
      
      

   2. Pull liquid through with a syringe attached with a small piece of soft plastic tubing to the nebulizer inlet. Block the nebulizer gas inlet side arm. Place the tip of the nebulizer in the liquid and draw the liquid through the sample inlet end. 

   3. Rinse with de-ionized water.

3. If the blockage remains, use one or more of the following cleaning steps:
   1. Attach a gas hose to the side arm of the nebulizer. Gently flush with laboratory grade air or nitrogen.
   2. Soak the nebulizer overnight in concentrated nitric acid. Use a Pasteur pipetted to gently fill the central capillary then submerse the entire nebulizer. Ensure that no air is trapped in the capillary.
   3.  To remove salts, soak the nebulizer in 25% detergent overnight. Use a Pasteur pipetted to gently fill the central capillary then submerse the entire nebulizer. Ensure that no air is trapped in the capillary.

      Warning: Wear Personal Protective Equipment when handling nitric acid, methanol, and laboratory detergents.

4. Rinse well with water and allow to dry before use.

5. Reinstall the nebulizer. 

Recommended maintenance schedule:  Agilent recommends weekly cleaning of the nebulizer. 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