Chromatography Forum

Hi all,

I use a Waters BEH C18 100 mm x 2.1 mm x 1.7 um

Flow: 0.3 ml/min
Gradient Mobile Phases: (95:5) 0.1% formic acid : ACN to 95% ACN
Pressure: 6000 - 8000 psi
Temp: 40ºC
Filterered mobile phases and samples.
Samples: animal extracts
Columns washed each 50 injections with 30 min 95%water and 30 min 95% ACN.
No pre-column.

Can you give me any idea of what kind of life time do you expect in such conditions?
Whould you like to share your column life times to give me an idea of what to expect from this one?
I am realy a litle bit in the dark here.

Thank you all!

It depends what all is in your animal extracts????? For example if you have fat in your sample, or Lipids, Peptides, Proteins it will Play a role.
Maybe you will get 500 injections without a guard column. Maybe you will get 500 injections with a guard column. It is impossible to tell you a number.
But if you get more than 500 injections be happy.

Thank you for your reply Gerhard.

I inject urine and liver extracts mostly.

Hi biotechno,

I use the same column and with pretty much the same samples. I easily get 1000 plus injections from it.

We use the same column (just the 150 mm version) on our system, but are running at approximately 13,000 psi back-pressure. Always filter the samples (0.22 um) and remove lipids and proteins, but have seen no difference in the column performance at well over 2000 injections, even at a low pH as you've discussed here.

I would expect, at that pressure, you will get a very long life out of the column.

This is a pretty hard question to answer. The real answer is that "it depends". I would suggest setting some requirements of what you want it to meet. This may be saying failing of a specific peak is NMT 2.0, resolution between two peaks is a certain value, or the k' of a certain number. It depends on what you are wanting from your chromatography. Continue to monitor and note when things get to the point that your chromatography is nolonger sufficient.

Yes, it makes sence.
How long a column lasts it depends alot on how much an analysis is sensitive to peak shape modification.

We work with multi detection so we have to be flexible about peak shapes.

And the work we are doing is too important to stop because of lack of budget so.. as long as we can garantee more or less the same level of detection and good calibration curves (R>95%) for quantification based on fortified samples, it will have to do.

My first column lasted 800 injection before we saw clear column void damage.

Thank you all for your help.