KB002010: What is Steam Cleaning in LC/MS? - General LC/MS 

To pass the vapours of solvents like IPA,Methanol,Acetonitrile,water through LCMSD system is called steam cleaning and is used to clean possible contamination in the LCMS system.
The usual conditions are: LC pump flow to 0.5 ml/min, nebulizer pressure to 60 psi, drying gas to 13 L/min, drying gas temp to 350 C, and if it is APCI, the vaporizer temp to 400C, and then make sure the MS stream selection valve is set to go to the “MS”
Steam cleaning overnight has been shown to be one of the most important factors in improving the signal-to-noise level by reducing the contaminations.
One of the solvent mixture found to be very valuable in cleaning LC systems, as well as LC/MS interfaces like ESI, consists of the following components: 25%:25%:50% Cyclohexane/Acetontirile/Isopropanol. However, this solvent mixture is used only for rinsing / steam cleaning and should not remain in the LC system for an extended period of time. It has been reported that cyclohexane may be harmful to the LC pump seals. Therefore, make sure to remove the solvent mixture from the system after the cleaning procedure is finished by flushing with IPA.
It is advised to use a union in place of column.