Contamination from ion-pairing agents.

[takvijay]

I used the tributylamine in mobile phase as an ion-pairining agent for the retention of acids on revered phase column. After doing lot off washing with different solvents, still i observed the peak at 186, which is definately from protonated tributylamine. I have also changed column, but the peak is there. Can anybody give the some useful tips to remove the contamination of tributylamine from the instrument.

[Steve Reimer]

At one point I had an HPLC that that I used for glyphosate by post column derivatization and on occasion, diquat. The diquat separation required diethyl amine in the mobile phase while the post column reaction converted amines to a fluorescent iso-indole. When the system was new I could make the conversion without difficulty with about a day of flushing and cleaning. After 4 years the cleaning process involved much more extensive dismantling and even replacement. I finally started borrowing a different HPLC to run the diquats, it was that bad.
The amine can reside on any surface the mobile phase contacts. Some are easy to wash off; tubing, pump heads, but others are harder to get to; e.g. sampling valve faces. I found that taking apart the sampling valve for cleaning saved a lot of grief, as did changing all frits in the system.

[Kostas Petritis]

Have a look in one of the previous posts:

http://www.sepsci.com/chromforum/viewto ... ight=rapid

As you can see triethylamine can be a huge problem when used with mass spectrometry (especially ion traps) and I would expect you to have similar problems from tributylamine