Shimadzu IonFocus Instruction Manual page 12

Introduction
Precautions for Mobile Phase Selection and Use
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IonFocus Unit
If PEEK resin parts are used in the plumbing, do NOT use the following mobile
phases.
These mobile phases weaken the PEEK resin, which could result in cracked
plumbing and mobile phase leaks.
Concentrated sulfuric acid, concentrated nitric acid, dichloroacetic acid, acetone,
tetrahydrofuran (THF), dichloromethane, chloroform, dimethyl sulfoxide
(DMSO).
Briefly using a weak solution of less than 0.5 % acetone in water
(e.g. in order to check gradient performance) will present no
problems.
Do NOT use a mobile phase that contains hexafluoroisopropanol (HFIP).
Plastic connections are used regardless of the tubing material.
This may weaken or break the plastic joints resulting in splashing of the solvent.
When performing analysis in which a halogenated mobile phase additive is
used, note the following:
In the APCI and ESI methods, the analyte is heated to high temperatures. If
the mobile phase contains a halogenated compound such as chloroform, a
corrosive gas will be produced. Even a small percentage concentration of
halogens in the mobile phase can cause corrosion.
Use SUS tubes to connect the high performance liquid chromatograph to the
instrument. PEEK resin tubes do not have sufficient strength and should they
rupture, solvent may blow out.
Black particles may build up on the APCI unit or ESI unit.
Because of exposure to corrosive gases, you may need to replace parts at a
shorter interval than specified.