Chromatography Forum

Hi I forwarded this from student projects. There seems to be more activity in this group.

Hi, I’m developing my first HPLC Method and I can’t seem to find any information on what is generally accepted as a minimum k’ for any given peak of interest. Any thoughts?

LCGC is a great source of information about LC method development. I especially enjoy Dolan's articles. I am a mass spec person, but do a lot of HPLC method development. The information in his articles has been invaluable.

see page 1 of

http://www.lcgcmag.com/lcgc/article/art ... ?id=131256

to answer your question.

When developing LCMS methods, I always make sure I retain the peak several column volumes. Especially in protein precipitated samples. There is often material at the first of the column from the sample matrix that can suppress the signal. I always prefer gradient methods over isocratic ones.

Good luck.

Thanks,
That's exactly what I was looking for.
CF

I just would like to make you notice that the "new" name for K' is K called "retention factor" formerly named "capacity factor"....

.....er, I thought the retention factor was given the symbol

k

That's small case italic. K means something else.

As my chem. teacher used to say, "A 'k' is a 'k' is a 'k' . . . "

....yes, you're right it's "k "and not "K", but the comment is still available on change of k' to k....

Provetech

I'm glad we agree .

k is the IUPAC symbol for retention factor, the artist (!!) formerly known as k'.

However, k or k' should not be confused with K which refers to the partition ratio. The partition ratio in chromatography is related to the retention factor via the phase ratio of the chromatographic system.

So a k is a k is a k' but never a K

Chemistry is confusing with symbols. k is often used for the Boltzmann constant and K for the absolute temperature etc etc. Perhaps we should have adopted Chinese characters instead. There are many more than 26 available.

Victor, I believe that the USP and ICH documents (which chromatographers in the pharmaceutical industry must follow) still use k'. (This causes some confusion for us in our short courses!)

To reiterate James Little's comments on LCGC and Dolan's articles - they are goldmines of information. My personal favorite is the series 'Starting out right', in , I think 5 parts starting January 2000.