• Created : 
  • Modified : 
  • Category :  Agilent Knowledge Portal
  • Entry Type :  Article
  • Product Type :  Analytical LC Systems
  • Component :  LC Detectors
  • Product Name :  1260 Infinity II LC System 1260 Infinity III LC System 1260 Infinity LC System
  • Task :  Troubleshooting
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Basic Troubleshooting for the Agilent 1260 and 1260 II ELSD

Answer

This Information Applies To: Agilent 1260 Infinity and 1260 Infinity II ELSD (G4260B)

Issue

When facing issues in the ELSD like broad peaks, or high pressure, it is important to identify its origin.

This information will help you to solve the issue, or to provide the Agilent Service Representative with the necessary information to do so.

Steps to Follow

ELSD high pressure

High-pressure issues are usually originated from a blocked nebulizer. A flush can remove the blockage.

  
Tips: Recommended solvents for the ELSD flush are Acetone/Water (50/50), Hexane/IPA (50/50), THF, DCM. 
  1. Disconnect the column and install a union instead. 
  2. Set the ELSD to the following conditions:

    Evaporator temperature 40 °C Nebulizer temperature 40 °C Gas flow 1.6 SLM

    Table 1: Specified conditions for ELSD settings.

  3. Connect the ELSD directly to the HPLC pump (bypassing the autosampler and column)
  4. Pump the cleaning solvent into the instrument at 1 or 2 mL/min
  5. Perform this procedure overnight or for a minimum of 4 hours.
  6. During the cleaning procedure, the ELSD response may show a full-scale deflection. It is an indication of the contamination being flushed from the detector.
  7. Following the cleaning procedure, reconnect the column and autosampler and inject a sample of known response.
  8. Repeat the wash procedure with a different solvent, or for a longer period if the ELSD signal is not improved.
  9. If there is no improvement, the nebulizer should be replaced. 

Increased noise/loss of signal

  1. Confirm connection of data acquisition cable to PC. 
  2. Check that the nitrogen supply pressure is within specifications, the regulator limiting pressure could be at 45 psi when recommended is 60 to 100 psi.
  3. If there is not enough pressure from the supply, the MFC will not deliver enough pressure to the nebulizer. It will cause that the droplets are not small enough, and more sample will go to the waste, because nebulizing is not working properly.
  4. Make sure that the waste tube is not emerged. 
  5. The diffuser may have a liquid surplus causing loss of signal and/or an increased baseline.
    1. Increase the gas flow to 2.8 SLM.
    2. Increase the evaporator to maximum temperature.
    3. Remain on those conditions for 1 hour.
    4. If the preceding steps do not make any improvement, then replace the diffuser.

High background

It usually happens when the evaporator tube becomes contaminated with nonvolatile material resulting in high background or poor chromatography.

  1. Use a 1:1 mixture of acetone/water at a flow rate of 1 to 2 ml/min.
  2. Set the evaporator temperature to 40 °C.
  3. Set the nebulizer temperatures at 40 °C.
  4. Set the gas flow to 2.8 SLM.
  
Tips: It is recommended to clean the evaporator tube once a week or every 40 hours of use as a preventive routine.

Poor RSD

  1. If there is another detector on system, check the reproducibility using that to rule out the sampling system.
  2. See if the nitrogen supply pressure is within specifications, the regulator limiting pressure could be lower than the recommended pressure of 60 to 100 psi.
  3. If there is not enough pressure from the supply, the MFC will not deliver enough pressure to the nebulizer. It will cause that the droplets are not small enough, and more sample will go to the waste, because nebulizing is not working properly.
  4. Surface and height can be fluctuating because of the waste tube. Please make sure that the waste tube is not emerged. Also, the waste bin level must remain low, otherwise it would cause a moistened environment within the waste tube, so there would be also more moisture in ELSD, causing higher offset.
  5. Temperature and humidity can also induce those symptoms.

Broad peaks

Reset gas to optics and nebulizer, then run the instrument until "Ready" status is achieved. Then check the autozero function.

In the previous recommendations do not help to fix the issue, contact your local Agilent support representative.

 
Learn how to effectively operate your Agilent Infinity LC systems:
High Performance Liquid Chromatography Learning Paths e-learning paths available from Agilent education.
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