Nebulizer Needle Replacement in an Agilent Jet Stream or Standard Electrospray Ion Source

Answer

This Information Applies To: Agilent 6000 Series LC/MS systems.

Issue

Efficient electrospray ionization (ESI) in your LC/MS ion source requires a properly adjusted nebulizer needle in good condition. The nebulizer needle is a consumable item in your ion source that may need to be replaced when the following signs are observed:

• Increased LC backpressure associated to the MSD.
• Off-axis spraying
• Dripping from the Nebulizer
• Poor or inconsistent spray shape

This article describes how to replace the nebulizer needle in the ion source of your Agilent LC/MS system.

Required Items

• Clean powder free nitrile gloves
• Nebulizer Adjustment Fixture (Part of the Nebulizer Adjustment Kit, p/n G1960-67470)
• T6 Torx driver (Agilent p/n 8710-2548)
• 2 x 1/4-inch x 5/16-inch open-end wrench
• Nebulizer needle replacement kit - select one of the following depending on the ion source type installed on your instrument:
  • G1946-68703 - Replacement needle kit or standard ESI sources, not compatible with Agilent Jet Stream (AJS) sources
  • G1958-60137 - Replacement needle kit for AJS Nebulizer, not compatible with standard Agilent ESI sources

Steps to follow

1. Put on clean powder free nitrile gloves

2. Determine the nebulizer holder type by comparing your nebulizer to Figure 1.

   
   
   Figure 1. Nebulizer holder type
   Left - Nebulizer with locknut; Center - Nebulizer with Torx screw; Right - Nebulizer with hex screw and 3 mm wrench
   
   

   Caution:  When inserting the nebulizer into the nebulizer adjustment fixture, ensure that the nebulizer tip does not contact the fixture, or the nebulizer needle tip may be damaged.

    

3. Mount the nebulizer assembly into the nebulizer adjustment fixture as shown in Figure 2. 
   Slide the heads of the two spring loaded socket head cap screws through the mounting holes of the nebulizer.
   Twist the nebulizer clockwise to hold the nebulizer assembly firmly in the fixture.
   Gently tighten these screws further to hold the nebulizer firmly in the holder.

   
   
   Figure 2. Inserting and tightening the nebulizer assembly into the nebulizer adjustment fixture
   

4. Loosen the locknut next to the zero-dead-volume (ZDV) union and then remove the union from the nebulizer needle holder, as show in Figure 3.

   
   
   Figure 3. Loosening the lock nut and removing the union from the nebulizer.
   

5. Remove the union locknut from the nebulizer.

6. Loosen the fastener (locknut, 1.5 mm hex screw, or T6 Torx screw that secures the needle holder in place. (See Figure 1)

7. Loosen the needle holder and pull it out of the nebulizer body.
   Dispose of the used needle safely according to your laboratory disposal protocols. See Figure 4.

   
   
   Figure 4. Removing needle and needle holder from the nebulizer body.
   

8. For a more thorough cleaning, remove the nebulizer body from the adjustment fixture block, then sonicate the nebulizer body in LC/MS-grade isopropanol (IPA) or methanol for a least 15 minutes.
   You can also pour the cleaning solvent through inside the nebulizer shaft.
   Dry the nebulizer body completely and then reinstall on the adjustment fixture block.

    

   Caution: Do not bend the needle in the next steps as you slide the needle into the ferrule. The needle is fragile, and a bent needle results in poor alignment with the nebulizer body.

    

9. Carefully remove the new needle from the shipping tube and identify the sharp and blunt end of the needle. See Figure 5.

10. Slide the blunt end of the needle through the needle holder and into a new black ferrule until 1 cm of the blunt end of the needle sticks out of the ferrule. Then push the needle back into the needle holder until the blunt end of the needle is flush with the end of the ferrule. See Figure 5 for more detail.

    
    
    Figure 5. Inserting the blunt end of the new needle into the needle holder and ferrule.
    
    

11. Reinstall the locknut and the union, then hand tighten the union onto the end of the needle holder.

12. Hold the needle holder steady on a clean surface with either a 3 mm open-end wrench or 1/4-inch x 5/16-inch open-end wrench (depends on your nebulizer holder style),
    Tighten the union 1/2 to 3/4 of a turn, or until an audible squeak is heard. The ferrule is now compressed onto the needle, see Figure 6.

    
    
    Figure 6. Installing the lock nut and union onto the needle holder, then compressing the ferrule onto the needle.

13. With clean gloves, pull carefully on the needle to ensure that the needle is held firmly in place by the compressed ferrule.
    Take care of the sharp end of the needle when performing this check.

14. Insert the needle and needle holder into the nebulizer body and turn the needle holder to engage the thread in the nebulizer body, see Figure 7.

    
    
    Figure 7. Installing the needle holder into the nebulizer body.
    

15. Adjust the new nebulizer needle to the correct position by following these instructions: How to Check and Adjust the Nebulizer Needle on Agilent LC/MS Systems
    

Learn how to effectively operate and maintain your Agilent LC/MS system Essential Housekeeping Tasks and Best Practices for Agilent 6400 Series LC/TQ e-learning course available from Agilent education