Passivation

[gincot]

I was reading a book about HPLC and the passivation with HNO3 6M was recommended once a month.

It is the first time I was hearing about this. I am afraid to use it.
Does anyone use this technique ?

Thank you

[grzesiek]

are you sure it was written "once a month" ?

I didn't use it and never got any problem

[gincot]

Yes I am sure. I still have the book.

We have agilent and shimadzu equipments and no where in the manuel this technique is mentionned

[bhuvfe]

Once a month is really too much. Unless you have an application that creates
a very noisy baseline on your detector afters such a short time.

We use it only when needed, i.e. to clean a refractive index cell or a diode-array cell.

[Kostas Petritis]

I would use it only if my application requires it or for cleaning purposes...

[gincot]

thank you

[lmh]

and do be careful, anyone reading this thread. In a building less than 100m from where I write, someone once blew up a winchester bottle of hplc waste by pumping nitric acid during passivation into the bottle which already contained isopropanol.

Before anyone denies it's possible, it really happened, and there's a UK health and safety executive report on this incident somewhere.

[gincot]

I did it and the system recovered a fairly good sensitivity, if I use a stronger mobile phase. I still can see some masses on the scan of the mobile phase, that were not there before.

The system was very dirty so I had to disconnect and use the ultrason for some fittings. They came out as new.

The system was so dirty that I am not sure that the mixer and the pulse dampener are clean again. I don't know how is built a mixer and a dampener. Could they be put in the ultrason bath with acid, would it do something good.

They have used tropolone in the mobil phase to complex organo-metallic
And it is every where