Minimum k

[cafran]

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?

[james little]

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.

[cafran]

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

[Provetech]

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

[Victor]

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

k

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

[DR]

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

[Provetech]

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

[Victor]

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.

[tom jupille]

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!)

[BigGeoff]

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.