Chromatography Forum

hi...

I'm using a BDS HYPERSIL C18 5microns column for my method,,,,the column dies after around 50 injections:: these are my mobile phase conditions:: 90% Sodium Phosphate Buffet pH = 7.5, 10% ACN, with 0.1% TEA,Instrument Parameters: temp:35C, flow rate: 1ml/min, injection volume;10microl... i am just wondering what's killing the column, none of my conditions are too extreme,, please helppppp!!!!!

I guess that Sodium phosphat buffer with 90% is killing your column if you use a brand new column and connect it. Shipping solvent is usually 70 % ACN. Do you see that back pressure is increasing? Please rinse your column with 90% water and 10% ACN before using your mobile phase, I mean your next new column. Please start with a lower flow rate and check back pressure. Good luck. BR Gerhard

Are you sure the problem is mobile phase and not sample?

Because the column is deteriorating quickly, you can apply the following diagnostic test:
http://www.lcresources.com/resources/TSWiz/hs390.htm

The samples are all filtered on a 0.45 microm PVDF filter prior to injection...

Do you add the TEA after you measured the buffer pH?

What is the concentration of the sodium phosphate? For example a 10mM solution running a 90%. Also if you premix the mobile phase does it precipitate out of solution?

I add the TEA before I measure the buffer pH.... and i adjust the pH with Sodium Hydroxide...

I use 0.02 M Sodium Phosphate...

Still tough to tell what the problem is. Some columns, especially those of an older style, are suffering under your mobile phase conditions. It is also possible that you have some gunk in your sample that we have not yet talked about...

this is Arun from Aravind. now i am using C18 mm and 100A silca column..to wash the column we using ACN 100%.
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