Chromatography Forum

Hi All,
Does anyone have experience with Agilent pumps rusting? I saw one post here in 2008. We've had two pumps now with issues.

I am seeing a reddish discoloration on our pump head, outlet check valve threads. We also are getting a lot of leaks from the pump and AS capillaries. I do not recall ever having to change a stainless capillary as often as I have been this past year (at least 30 times - same and different caps).
We are running fairly conc. TFA (per Agilent Method Dev. folks) - 0.1% TFA/H2O (pump A)and 0.4%TFA/AcN (pump B).

Agilent has replaced one pump with a demo unit and after 3 months this one is experiencing leaks (3 in the past month). As we are under service contract.
Agilent has been extremely slow to respond - and do not understand why we have so many leaks.

The strange thing is - we have an Agilent 1200 Quaternary HPLC with the same mobile phase - it never leaks.

Could they have a raw materials issue with their stainless steel?

Regards,
Schpen

Could they have a raw materials issue with their stainless steel?

It's possible. I've seen it happen (not with Agilent). A supplier decided to take short-cut and use 304 stainless steel instead of 316. The claimed it was a "mistake", but any machinist worth his/her salt should have been able to tell the difference immediately (316 is much harder).

You can get a test kit to tell them apart, but it ain't cheap (US$350):
http://www.koslow.com/metaltestkit.html

316SS should hold up to 0.x% TFA without any problems. If this were my issue, I'd lean on the local Agilent sales rep to put pressure on the service people.

Hello.
Recomendations , respected Tom Jupille , absolutely true.
However, a more interesting is not the first ask question Chernyshevsky "Who's to blame?" , but the answer to the second "What is do ?"

In addition to contacting a service we can recommend the following items of the event.
1) Threaded connections certainly damaged. You must use the capillaries and fittings PEEK
2) The system should be flushed with 10% citric acid solution, and passivate 67% nitric acid, flush 5-10 ml with a minimum speed and thoroughly washing off the system with water (1 L + 1 drop of ammonia solution). Column at this point should be removed and replaced by a capillar.
3) You should refuse to corrosive agents - HCL, trichloroacetic and trifluoroacetic acid, sodium chloride.
Google translate

Thanks Tom and thanks Moscow,

Here is the reply from our service manager at Agilent:

"
The TFA will cause the brown/red colorations, this happens on surfaces that are outside the flow path. When leaks, even micro leaks occur areas around the threads and edges of the pump with show the brown/red discoloration. The 0.4% TFA is likely leading to fast discoloration and eventual weakening of the connections and that leads to more leakage. Now that you have reduced the TFA to 0.1% I will have a new pump head installed. The threads for fittings are the first to show the colorations."

Pump head A uses 0.1TFA/H2O - this pump has red discoloration on the outlet valve as well. Both pump heads have been a problem in the past for "micro" leaks.
Apparently , Agilent's 'High end" - SL (superior line - my boss says "Super Lousy") - cannot use TFA as an ion pairing agent >= 0.1%. Between -two HPLC systems - a total of 5 pump heads and numerous autosampler capillaries.

To Moscow: I would like to change all the fittings to PEEK . I was afraid of the high pressure (the SL is a 600 bar system) but from what I understand PEEK can withstand up to 7000psi. Thank you for your suggestion.

-Regards