Hypersil or Luna for Ion-Pairing HPLC?

[Judy]

My work involves separating an indandione from animal tissue samples, and we are currently looking at buying an HPLC column.

The indandione is a weak acid and forms an enolate ion in solution. The separation involves using reversed phase ion-pairing. Most literature sited using Hypersil ODS C18 (250x4.6mm 5um) column, whilst some used the Phenomenex Luna ODS C18. The mobile phases are going to be tetrabutyl phosphate ammonium in methanol and PIC Reagent A (same salt but in water).

I would greatly appreciate any feedbacks on the above mentioned columns, or any other brands people have used and worked well. We are looking for a column that will give good peaks, reproducible results and durability perferably over the next 3-4 years of my PhD life.

Thanks heaps!

[Uwe Neue]

I believe that several columns will do the job, considering that you will use an ion-pair reagent for the separation (which equals out some of the differences between different columns).

However, I believe that your are dreaming, if you think that you will be able to use the same column over 3-4 years with a extracts from animal tissue samples. In addition, you will need to work hard on a sample cleanup scheme to get even a reasonable number of injections out of your column.

(Trust me, I speak from experience... I killed one of my first columns with an injection of 20 microL of milk in a single shot.)

[pawan ratra]

Although column life depends on number of factors, I prefer Luna C18 personally as it contains high carbon load which provides more retention and hence separation, high surface area, endcapped to reduce silanol activity and less lot to lot variability.

[Victor]

I'm sure this method would work on many columns but reproducing a published method is attractive since (in theory at least!) it should work without any need for adaptation, which may be attractive for you.

In the absence of any other factors (e.g. big price difference) I might go for the Phenomenex column. THis is a newer design phase which is based on a purer silica; Hypersil is an older type of phase that has been around for at least 20 years. This is not to say that there are newer versions of Hypersil around based on pure silicas, but if you do not have a published method around which uses that particular phase, some method development might be necessary.

[josebenjamin]

Judy,

You already received several comments. I would like to add the following: One of the desirable characteristics of a column for IP separations is the rapid equilibration with mobile phase reagents. This is best accomplished with a "monomeric" stationary phase. Also, since you may want to use IP for compounds that interact heavily with free silanols, then you also would like to use an end-capped column.

I would recommend you to consult the Phenomenex catalog, there somewhere, you will find an extensive table of silica material for HPLC with some description of properties and treatments (particle, coating, endcapping, etc). Either one of the ones you mentioned, it is likely to be described there and then you will be better able to make a good decision.

If both materials are comparable then perhaps you will be better off with a more modern column. Hypersil has been around for a long time, and I am not sure how much the production process has been inproved.

good luck,

josebenjamin

[Uwe Neue]

As I have said before, no column in the whole world will last for 3-4 years. On the other hand, there is only one column with a literature-proven superior reproducibility to anything else that is on the market: Symmetry C18. Thus if you need to get the same results as today 4 years from now, there is only one choice: Symmetry C18.

[pawan ratra]

my experience with symmetry c18 is also good. But the column life is not good in presence of TEA.