Chromatography Forum

does anyone know the most orthogonal phenyl column compared to conventional C18 column.

There is no single answer to that because there is a fair range of selectivity variation with C18 columns. Also, the selectivity of any given column will depend on the exact sample (acids vs. bases, for example) and on the mobile phase pH (because of silanol ionization effects).

If this were my problem, here's what I would do:

Go to the PQRI database on the USP website:
http://www.usp.org/USPNF/columnsDB.html go to "compare columns" and scroll down halfway.

Pick the specific C18 column to use as a reference, select "view different" and then page down until you come to a phenyl column.

Hi Tom,

thank your for your answer.
But I am aware of fact that this hydrophobic subtraction model does not take account in (a) dispersion interactions of varying strength as a result of significant differences in bonded-phase polarizability or refractive index and (b)
pi-pi interactions in the case of phenyl columns and aromatic solutes.
So it will not give you reliable answer for the most different phenyl column compared to conventional C18 column.
my purpose of application is to use a very different phenyl in the second dimension to separate my phenyalkyl compounds from non-aromatic coelutes from first dimensional separation.

There is no single answer to that because there is a fair range of selectivity variation with C18 columns. Also, the selectivity of any given column will depend on the exact sample (acids vs. bases, for example) and on the mobile phase pH (because of silanol ionization effects).

If this were my problem, here's what I would do:

Go to the PQRI database on the USP website:
http://www.usp.org/USPNF/columnsDB.html go to "compare columns" and scroll down halfway.

Pick the specific C18 column to use as a reference, select "view different" and then page down until you come to a phenyl column.

So it will not give you reliable answer for the most different phenyl column compared to conventional C18 column.

I'll defer to people with more knowledge than me on that one! In any case, though, there is enough variability within C18 columns that I don't think you can find one "most different" phenyl for your sample without doing the experimental work.

Thanks so much for your help.
I guess I want one most different phenyl column to one idea conceptual C18 column (only hydrophobicity).

So it will not give you reliable answer for the most different phenyl column compared to conventional C18 column.

I'll defer to people with more knowledge than me on that one! In any case, though, there is enough variability within C18 columns that I don't think you can find one "most different" phenyl for your sample without doing the experimental work.

There are various types of phenyl-type phases, such as propyl phenyl, hexyl phenyl, bi-phenyl, di-phenyl, etc. Acclaim Phenyl-1 column (Thermo Scientific) is unique compared to any other phenyl-type columns mainly becuase of its electron-withdrawing property. Figure 4 in the following link demonstrates such difference in PAH selectivity (http://www.dionex.com/en-us/webdocs/875 ... 550-01.pdf). I hope this information helps.

thanks. but i want less retentive phenyl column.

There are various types of phenyl-type phases, such as propyl phenyl, hexyl phenyl, bi-phenyl, di-phenyl, etc. Acclaim Phenyl-1 column (Thermo Scientific) is unique compared to any other phenyl-type columns mainly becuase of its electron-withdrawing property. Figure 4 in the following link demonstrates such difference in PAH selectivity (http://www.dionex.com/en-us/webdocs/875 ... 550-01.pdf). I hope this information helps.

Hypersil Gold PFP has lower retention and unique selectivity (http://www.leacsa.com/pdf/Hypersil/Hype ... %20PFP.pdf).