Chromatography Forum

Hi all,

I had a mishap with an rx-sil column today and am looking for a way to wash/restore the column. Not sure what the best strategy is for flushing everything out.

I am using a preparatory reverse-phase rx-sil column with ethanol and water as solvents (95-100% etOH). The sample I'm injecting is in DMSO due to solubility issues.

We always make the manual injection with a standard 3mL syringe. Today I used a 1mL syringe, of the exact same make and model. Apparently, however, this syringe features a different plastic and rubber stopper that is NOT compatible with DMSO. Unbeknownst to me, as I injected my sample, I was also injecting some dissolved plastic/rubber from the syringe. Column was not happy, pressure immediately jumped past 400 bar.

I have replaced the guard column and washed the column on reverse for 2 hours with 70/30 Etoh/water. Replacing guard column had little effect on pressure. On reverse flow, pressures were normal for our method (~230 bar). When I return to forward flow, pressures remain high (~350 bar). I tried cleaning the inlet frit as well as possible without removing it. There aren't any visible blockages. Also confirmed there aren't blockages elsewhere in the system.

I'm currently reverse washing with 50/50 EtOH/water. Wondering if anyone has ideas for a powerful but compatible wash solution to really get rid of all this plastic.

Let me know your thoughts/ideas.

Since your junk apparently dissolves in DMSO, how about some DMSO in EtOH? DMSO has a high viscosity, so maybe something like 10% and see what happens.

I'm afraid but think that your column is killed. Flushing with DMSO in the eluent will help a little bit but will not solve the problem 100%. Sorry, but best in my opinion is to purchase a new column. Good luck.

Since you have nothing to loose , try reverse flushing with THF .
Do not connect the outlet anywhere , just put a beaker under the column.

PEEK parts , if any , may be effected during washing with THF but not in a very short time.

Here's more info:

I have not yet tried the posted solutions. After a long reverse wash, I returned the column to normal direction again. The pressures looked great. I equilibration for a long time and then injected another sample.

As soon as I injected my sample in DMSO, the pressure again shot up past 400. Also, there was a repetitive clicking or pinging sound coming from the column.

Anyone know what that clicking noise indicates? Can't find anything online. Does not sound good.

The column is a stainless steel tubing packed with modified silica. There is nothing in and on the column what can give any noise. Maybe you can hear a check valve or some noise from the pump head.

I once heard this kind of noise when the buffer precipitated in the column and the pressure went very high.

The noise was something like popcorn or cracking sound.

If the situation is this , then nothing to do with the column , throw it away.