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bergamin.a@wehi.edu.au

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January 9, 2022
EchoMS OPI Leakage Issue

What is the best way to determine if a recurrent OPI leak during standard operation is due to a faulty/ fouled OPI probe head or a fouled/damaged electrode or poor flow rate optimization?

 

If you replace the OPI probe head or OPP, what is the protocol for this? Is a new electrode also installed? Is flowrate optimisation required again?

 

The OPI probe head seems like it has an accumulation of precipitate externally which can be removed with water, how is this best avoided?

 

Has anyone else had recurrent OPI leaks and how have you dealt with them?

 

Thanks for your help!

 

 

1 Comment

  1. Mackenzie Pearson

    1. What is the best way to determine if a recurrent OPI leak during standard operation is due to a faulty/ fouled OPI probe head or a fouled/damaged electrode or poor flow rate optimization?
    • Most instances I’ve observed are due to particulate accumulating inside the ID of the PEEKSIL tubing or at the end of the ESI portion of the electrode. Occluding the OPI is unlikely due to the larger ID and no application of energy (heat, electricity) to that end versus the other (small 200uM ID tubing with heat and electricity). I would use the pharma mix in neat solution to confirm flow/equilibration between the gas and mobile phase to test that it is optimal. As the PEEKsil becoming contaminated internally it will slow. To correct, reoptimize flow to match the new equilibrium.
    • If this doesn’t work, please request a service visit to have them test the flow rate from the pump module to ensure it is delivering the flow rate the computer is reading.
    2. If you replace the OPI probe head or OPP, what is the protocol for this? Is a new electrode also installed? Is flowrate optimisation required again?
    • The OPP head would need to be replaced by service. This is something that needs extensive reoptimization.
    • If the OPP is replaced, a new Peeksil/electrode assembly is not mandatory. Whether or not the electrode is replaced after the OPP is replaced you will want to reoptimize your flow rate as we do not have a known value for this OPI’s equilibrium when mated to GS1.
    3. The OPI probe head seems like it has an accumulation of precipitate externally which can be removed with water, how is this best avoided?
    • Operating significantly below the equilibrium flow rate will produce the issues described due to the effects of super vortex or not enough carrier flow to wet the external surfaces of the ID of the OPI. This system is about equilibrium, too low a carrier flow problem occurs and too high a different problems will occur. If the OPI becomes occluded or dirty, perform the Replace electrode procedure in the maintenance portion of the direct control for EchoMS to remove the PEEKsil electrode. Take a squirt bottle of water and thoroughly rinse the OPI from the top down. Be liberal with your quirt bottle and apply a steady stream of water to dissolve contaminants. Re-insert the PEEKsil electrode and replace the coupling fluid of the system as all the contaminants are now present in the coupling fluid.
    4. Has anyone else had recurrent OPI leaks and how have you dealt with them?
    • One other thing to ensure is that an overabundance of flushing of the OPI is occurring. Set the idle time to 30-90 minutes to let the system flush before it goes into standby mode to help prevent precipitation buildup. Precipitation is most prevalent when the system is placed into standby immediately after samples are run without allowing the system to flush itself clean.

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