Chromatography Forum

Hi There

I am using normal-phase (hexane and isopropanol) and they advice me to use rear seal wash water isopropanol 40:60. It was fine for some time but it seems that the detector is not detecting the solution. Any other suggestion for the composition of the rear seal wash?
thanks

The detector should *not* detect the seal wash solution. The only situation where I can see that happening is if the seals are in very bad shape, and in that situation I would expect the first symptom to be mobile phase in the wash.

No need to seal wash for normal-phase , it is usually required for reverse -phase mobile phases ,containing salts.
When reverse-phase solvents evaporate at the back side of the piston , it leaves salt deposits behind , which shorten the life of both the piston and seal and causes leaks.

Normal phase mobile phases ; like hexan and IPA ; easily evaporate at the back side of the piston , leaving nothing behind it.