column lifetime

[n-cute]

Helo All,

Little more than 1500 injections (injection volume 50 µl ) of food samples and my column is "down". Isn't it too small number of injections? I use pre-column, samples looks clear.

Thanks for your opinions
N-cute

[juddc]

Please define "down". Do you mean excess pressure, poor resolution, loss of efficiency, or all three?

1500 50 uL injections of a complex sample onto a good quality column before replacement is needed seems reasonable to me on the face of it. I've seen columns run 2-3 times that number and I've seen them run 1/3 that depending on the particular column, sample, and analytical conditions, all with careful sample preparation, good mobile phase preparation technique, and good column storage practice on well maintained instrumentation. I'm lucky: I've had absolute control of the LC's in my laboratory for many years.

My read on this is that you haven't much to worry about. Buy another column and keep running.

[tom jupille]

I'll second juddc's comments. Column lifetime depends on a large number of factors, not the least of which is the robustness of the method with respect to column chemistry. A robust method will tolerate a great deal of column degradation before it fails. A non-robust method may fail with only a slight change in column chemistry.

Look at it this way: if you get 1500 injections from a $300 column, your column cost is only $0.20/injection.