Flushing HP Plot U Capillary column

[DocHollywood]

I have an HP Plot U Capillary column. I think it became contaminated after a colleague injected formic acid because now i get two or three peaks near the end of the run that I can't get rid of. I've tried conditioning it. Didn't work. I'm wondering if there is a way to flush it with a solvent? or any other solution?
Thanks
AD

[Ron]

I wouldn't expect flushing to work well on a PLOT column, they do shed some particles under the best of conditions, and rinsing the column would probably lead to massive particle loss. When I have had a contaminated PLOT column I just bit the bullet and got a new column if cutting off a meter or two didn't solve the problem.

[Bruce Hamilton]

Years ago, I was given a very expensive plot column by a supplier after a client had attempted to flush it with solvent. Some of the particles dislodged during flushing, and then blocked the column. The client blamed the manufacturer's quality systems. I managed to backflush it with a low viscosity solvent and HPLC pump, and partially opened the flowpath.

I used the column for about a decade with no problems, and the back pressure was consistent, but still three times the original value.

My advice would be to not try and flush with liquid, but to perform some large volume injections (eg 10 ul ) of a polar solvent ( ethanol, water ) every 5 minutes, initially at low temperatures until the formic peak disappears, then at 40-50C increments up to 190C.

Given it's a dimethacrylate, I'd be wary of aggressive solvents, but if one volatile, polar solvent doesn't work, try another. I'd also place an order for a replacement column.

Please keep having fun,

Bruce Hamilton

[DocHollywood]

Thanks for the responses. I will try the suggestions.
AD