HPLC nitric acid flush

[dkreller]

Hi,

I am getting geared up to give my LC (Waters Delta 600, 717plus A/S, 2487, 2475) a little spring cleaning. I am particularly concerned that I recently contaminated the system with some micron to nanometer size iron oxide particles. (Failed experiment trying to custom-pack a column with material that had a lot of fines....) In fact, I can see some rusty red buildup inside the transparent tubing I have as the last leg of my effluent line going into my waste jug. So I am going to flush the system with HNO3, to hopefully dissolve any metal oxides. Then follow with MeOH.

My Question: How much HNO3 can a system like this handle? I.e. what HNO3 concentration for how long?

Thanks,

Dave

Exams are done here (university in GA), and the summer is here, so you can't get the smile off my face....

[JGK]

Passivation procedure in this thread with recommendations

viewtopic.php?f=1&t=6840

[lmh]

Sorry if I'm telling you the obvious, but if you do passivate with a high concentration of nitric acid, make sure that you wash the system thoroughly with water before proceeding to organic solvents, and do not under any circumstances allow the nitric acid waste to go into the same container as organic solvents. In a building adjacent to mine, someone passivated an hplc with nitric acid, pumped into a waste bottle that contained isopropanol. Some hours later it exploded, badly damaging the instrument and the lab, and sadly injuring someone who happened to be in the vicinity. It's not an urban myth (I've seen the photos with my own eyes), it really can happen.

[Bluesman75]

In addition do not pump the acid through any degasser or detector cell.