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Stanford-ChEMH-MCAC / protocols

Laboratory protocols used by the Metabolite Chemistry Analysis Center, a ChEM-H Knowledge Center at Stanford University.
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failure to use correct tuning mix #5

Closed curt-f closed 6 years ago

curt-f commented 6 years ago

Hi all,

This morning a collaborator was having troubles calibrating the 6545 qTOF. Investigation revealed that the intensity of the lowest-mass calibration ion at an m/z of 118.0863 was very weak. There was also a very high intensity peak in the calibrant mix at an m/z of 121.0509.

This 121.0509 ion is present in the MMI-L tuning mix that is used for the mixed mode ionization ion source; however, the instrument (as almost always) was set up for the dual-AJS ESI ion source, which expects the 118.0863 calibrant.

Thus, I suspect someone used the wrong tuning mix to make up calibrant solution.

This means it is a good occaision for me to remind everyone of proper best practices.

  1. The protocol for making calibrant mix is at https://github.com/Stanford-ChEMH-MCAC/protocols/blob/master/instrument_maintenace_and_configuration/tuning_mix.md Please follow this protocol.

  2. Please check which ion source you are using and which tuning mix concentrate you are using.

  3. If any information in these protocols is unclear, let me know (a) by email or (b) by filing an issue on Github for the corresponding protocol.

curt-f commented 6 years ago

https://github.com/Stanford-ChEMH-MCAC/protocols/commit/7e7a91c609852d1b658430374f81963712557043