Chromatography Forum

What can I expect for column lifetime when doing rapid resolution chromatography with balistic gradients on a 2.1*20 mm Sub-2µm reversed phase column? My mobile phases will be Acetonitrile and Water both with 0.1% Formic acid. How many injections can one make before the column starts to deteriorate?

That depends primarily on the quality of your sample prep technique. I have seen over 2000 injections after a solid protein precipitation, but I am more comfortable to bet on 500+ injections. It also may depend on the quality of your gradient procedure.

I have some experience in High-through put LC/MS for library chemistry, we use ACN and water with 0.01% TFA as MP, and use 2.1*50mm,5um column. In average we could ran about 10,000 injections for one column. But we also use MP with 1mM NH4COOH in ACN and water, it only ran about 5000 injections.

We have 5 LC/MS, and each LC/MS ran almost 24*7 Hr per week.

Sorry, I had assumed that you are dealing with a sample of biological origin, such as a plasma sample. For any sample, column lifetime depends on the amount of junk one puts on the column. For very clean samples and clean mobile phases, columns can last much longer.

A long time ago, I demonstrated that a column does not even change in 10 000 injections, if it is protected by guard columns.

Also depends on which column you use. At the 2005 BMSS meeting there was a presentation from GSK covering some work they'd done with sub 2 micron columns. They noted a difference in lifetime between different manufacturers columns. Examples were 1 brand lasting only ~400 injections while others were ok after 2000.

I did a lot of plasma analyses with protein precipitation. See

http://users.chartertn.net/slittle/default.htm

first topic, the text.pdf document

Initially we used a guard column very successfully getting 200 to 400 injections before changing the guard column. However, after a while we noticed that the guard columns being supplied were not as high a quality. I would test the guard column individually and found that it significantly decreased the quality of the separation. Thus, I then started to just use the column alone.

I then could get 400-800 injections before the quality of the separation decreased. I often changed (usually every 200 injections the 0.25 micron filter before the column if the backpressure increased significantly.

Often I could clean the column (10 or so column volumes) by backflushing with water/methanol (90/10) containing 1% formic followed by water/methanol (5/95) containing 1% formic, then just pure methanol. The columns would then often be OK.

A lot of our columns used in routine analysis fail due to compression of the bed. You can take the frit off the front of the column and see the compression. We have slurried some stationary phase and added it to the front of the column and brought the columns back to their initial performace spec. Sometimes if the column is very discolored at the head of the bed, we scrape out a little of the bed and then top it off with some more slurry, and carry it through the washing.

Depends on how much you value your time. Most people consider columns disposable after a reasonable number of injections. Looking at the mode of failure might give you insight into selection of a more robust column..