Cleaning the Agilent ICP-OES Spray Chamber

Answer

This Information Applies To: Agilent 5100, 5110, 5800, 5900 ICP-OES systems

Issue

The ICP-OES spray chamber filters the sample droplets created by the nebulizer. Larger droplets fall to the chamber drain, while the smaller droplets are introduced to the gas flow going into the ICP torch plasma. A dirty spray chamber causes large droplets to form, which leads to incomplete transfer of sample to the torch, causing poor precision and memory effects. 

ICP-OES overview 

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

How to identify a dirty spray chamber

Routine analysis of aqueous and nonaqueous samples using a single spray chamber will increase cleaning and instrument downtime. Agilent recommends the use of two spray chambers, one for aqueous solutions and one for organic solutions, to reduce downtime.

A clean spray chamber has a uniform mist on the internal surface (Figure 2). A dirty spray chamber has large droplets on the internal surfaces (Figure 3).

Figure 2: Correctly wetting spray chamber

Figure 3: Incorrectly wetting spray chamber

Steps to follow

1. Turn off the pump and plasma.

   Warning: The spray chamber may contain potentially dangerous chemicals, and the nitric acid and alkali detergent wash solutions are corrosive. Always wear Personal Protective Equipment when cleaning the spray chamber.

2. Remove the nebulizer (see Figure 1).
3. Remove the spray chamber and disconnect the tubing. This video demonstrates how to remove the spray chamber:
4. Rinse the spray chamber with 1% HNO3 solution then ASTM Type 1 water. 
5. Prepare an aqueous solution of a quality laboratory alkaline detergent. Completely immerse the spray chamber in the solution, ensuring all the internal surfaces of the spray chamber are in contact with the detergent solution.
6. For:
   • Single pass spray chambers: The container may be placed in an ultrasonic bath and sonicated for 40 minutes.
   • Multiple pass spray chambers: Do not sonicate, instead allow the spray chamber to stand overnight in the detergent solution.

     Caution: Sonicating a multiple pass spray chamber may cause damage.

7. Remove the spray chamber from the detergent solution and rinse thoroughly with ASTM Type 1 water.
8. Dry external surfaces using a clean, lint free paper towel. Do not dry the spray chamber using compressed gases.
9. Re-attach all tubes, adaptors, and the nebulizer. Reconnect the assembly to the instrument.
10. Test the cleaned spray chamber by nebulizing a blank solution and repeat the cleaning process if there are large droplets on the spray chamber internal surfaces.
    

    Tips: It is not unusual that some spray chambers will require extended cleaning.

11. If the spray chamber is not going to be used immediately after cleaning:
    • Store in an appropriate covered vessel containing a 1% HNO3 solution until required or,
    • Store the dried spray chamber in its original packaging.

Recommended maintenance schedule:  Agilent recommends weekly to monthly cleaning of the spray chamber. Analysis of samples with complex matrices may require more frequent cleaning.