ICP-MS Parafilm Test for Plasma Ignition Problems

Answer

This Information Applies To: Agilent ICP-MS systems (7700/7800/7850/7900/8800/8900)

Issue

This procedure tests for an air leak in the sample introduction system, or fault with spray chamber draining, by sealing the end of the torch with a piece of parafilm and testing plasma ignition. Sealing with parafilm isolates the torch from the rest of the sample introduction system. If the plasma ignites with the parafilm in place, the ICP-MS hardware is operational and the plasma ignition problem is due to a sample introduction fault.

Requirements

If the spray chamber has flooded (not draining properly), water droplets can enter the torch and extinguish the plasma. A wet torch will not light and may be irreversibly damaged by plasma ignition. Therefore, it is important to install a dry torch, inspect the condition of the bonnet and platinum shield, and replace any damaged components before continuing with the test.

Items Required

• Standard Torch, quartz, 2.5 mm id - not suitable for samples containing hydrofluoric acid. (p/n G3280-80053)
  see the Agilent Spectroscopy Supplies Catalog if you use a nonstandard torch
• Parafilm - Laboratory Sealing Film

Steps to Follow

Warning: The torch remains hot after the plasma is turned off. Do not touch the torch box for 10 minutes after turning off the plasma to let it cool.

1. Click here for instructions to remove and inspect the torch, bonnet, and platinum shield. Replace any damaged components before continuing.
   
   
2. Locate a new torch.
   

   Tip: Use a new torch to verify that the torch is dry at the start of testing. A wet torch will not light and may be irreversibly damaged by plasma ignition.

3. Assemble the torch.
   1. Install the platinum shield over the torch, ensuring the alignment hole in the shield fits over the torch projection (Figure 1, Item 1).
   2. Slide the bonnet over the platinum shield plate with the lip facing the base of the torch (Figure 1, Item 2).

      
      
      Figure 1. Torch, platinum shield, and bonnet assembled
      1. Platinum shield alignment hole and torch projection 2. Proper orientation of bonnet lip
      
      

4. Install the torch on the ICP-MS torch stand
   1. Carefully guide the end of the torch through the work coil and ensure the torch projection fits into the torch stand groove (Figure 2).

      
      
      Figure 2. Placement of torch on the torch stand
      
      

   2. Clamp the torch stand and attach the gas auxiliary and plasma gas tubes to the torch and tighten the connectors by hand (Figure 3).
      

       

      Caution: Figure 3 does not show tightening the gas connectors by hand. The connectors should be snug, but not overtightened. If you apply too much pressure, the torch will break.

      
      
      Figure 3. Torch stand clamped and gas lines attached
      
      

5. Seal the end of the torch that normally connects to the connection tube, with a piece of parafilm. DO NOT attach the connection tube. Remove the connection tube entirely, and leave the torch and parafilm as shown in Figure 4.
   

   
   
   Figure 4. End of torch sealed with parafilm
   
   

   
   

   Caution: Do not re-attach the connection tube with the parafilm in place, as this will create a closed system between the spray chamber and connection tube. When the nebulizer gas is turned on during plasma ignition, pressure will build within this closed system, which can lead to the spray chamber end cap or nebulizer popping off to relieve the pressure.

6. Refit and latch the torch compartment cover (Figure 5).

   
   
   Figure 5. Torch compartment cover installed
   
   

7. Close the ICP-MS small cover (Figure 6).

   
   
   Figure 6. ICP-MS small cover closed
   
   

8. Retry plasma ignition with parafilm in place.
   
   
9. If the ICP-MS reaches Analysis mode (the status indicator is solid green) the ICP-MS hardware is operational and the plasma ignition problem was due to a sample introduction fault. If the plasma ignition fails with parafilm in place, then a hardware or ignition issue may be present. Please contact your local Agilent Service Representative for further assistance.
   
   
10. Turn off the plasma.
    
    If plasma ignition was successful with the parafilm in place, the ICP-MS hardware is operational and the plasma ignition problem was due to a sample introduction fault such as:
    
    • There was a fault with the torch, bonnet, or platinum shield
    • The torch was wet from a flooded spray chamber.
    • Check that the spray chamber is draining properly. Check the condition of the peri-pump drain line tubing and that it is routed around the peri-pump in the proper direction. Replace the peri-pump drain line tubing. Check that the spray chamber drain is seated on the base of the spray chamber.
    • The peri-pump sample line tubing was not properly clamped or the tubing needs to be replaced.
    • There was an air leak in the sample introduction system somewhere between where the torch connects to the connection tube, and the nebulizer (including gas connections). Check that the spray chamber end cap is correctly fitted to the spray chamber. Reconnect all gas connections. Place a drop of de-ionized water on the connection tube ball joint and torch ball joint, then re-assemble the spray chamber, connection tube, and torch. If the ball joints are too dry, they can create an air leak.
      
      
11. Identify and resolve the sample introduction fault, remove the parafilm, reinstall all sample introduction components, and retry plasma ignition.

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