HPLC column high pressure due to starch precipitation

[Salvadorlopez]

Good morning,

I wonder if any of you have experienced problems with the starch precipitation in HPLC columns C18, 3.5µm. The pregelatined starch is partially soluble in water and the samples are prepared in a ACN:Water mixture due to the nature of the analyte. The gradient with ACN genarates the precipitation of starched dissolve in samples and the column starts giving problems after 600 injections. We have tried to rinse the clogged column with DMSO:water 50:50 but it has not been very successful.

[Gerhard Kratz]

First off all 600 injections is not so bad. Do you use a guard column?
Anyhow, in such a case please rinse your column ONLY by reversed flow!!! Without Connection to the detector.
You can also replace the frit at the column top.
What is your target compound? What Kind of sample preparation are you doing?
Final Option is - save time and Money and purchase a new column, with guard column. That will save you time and Money at the end of the day. Good luck

[HPLCaddict]

Gerhard already made some valuable comments. I'd like to add one further note: Are you sure that precipitated starch is actually your problem? I suppose your gradient starts with a water-rich mixture and starch, being quite polar, should elute very quickly from a hydrophobic C18 column even at that composition. At the time the mobile phase is ACN-rich enough to precipitate starch it should have already left the column...

[Parham]

Our friend already made some valuable comments. I'd like to add one further tips:Please back wash your column only with hot water while your column connection removed of detector, you can use of your column oven and heat it until 5 degree above recommended in your column catalogue. sonicate your column frits, if it dosen't work you can use your column for another usage.Good luck .