USP G16, G25 and G35 column difference

[sisay]

Hi all

I know that these three columns can be applied to the analysis of fatty acid.

The difference between G16 type and G25/G35 type is that the diepoxide in G16 type column is further esterified with terephthalic acid as G25 type and nitroterephthalic acid as G35 type respectively. I was wondering that what advantage is provided due to this modification? Does it prevent the column from damage or provide better column efficiency for specific target analyte? Hope you can help to answer my questions, thank you very much.

[GOM]

Hi

Out of interest are you analysing free fatty acids or fatty acid methyl esters?

Regards

Ralph

[dlbenach]

The G16 category contains the standard Wax (PEG) phases like DB-Wax, Stabilwax etc. G25 and G35 contains the FFAP phases. I use the FFAP columns when I need to analyze fatty acids in their acid form. The FFAP columns are better deactivated for acids and should give less tailing and better precision. If you are running USP<401>, your acids are in the methyl ester form and a G16 column works fine. If your analytes are in the acid form, a G25 or G35 is preffered.

[Consumer Products Guy]

Four decades in this business, and we always make methyl esters to assay fatty acids and metal salts of those. Typically I use a "2330" capillary.

[sisay]

Dear all

Thank you for all the information you provided. We analyze fatty acid methyl esters in magnesium stearate, so G16 column is preferred.

Happy holiday,