Chromatography Forum

Hi,

I have a C18 column with 90Å, 5 µm, 3.9 mm X 150 mm, and would like to add a guard column with 130Å, 5 µm, 3.9 mm X 5 mm or 90Å, 2.7 µm, 3.9 mm X 5 mm. Is it possible to use any of these two guard columns ?

Thanks.

Hi,
I have a C18 column with 90Å, 5 µm, 3.9 mm X 150 mm, and would like to add a guard column with 130Å, 5 µm, 3.9 mm X 5 mm or 90Å, 2.7 µm, 3.9 mm X 5 mm. Is it possible to use any of these two guard columns ?
Thanks.

ME: I would try, and use if the chromatography/separation(s) were good.

I believe that we often had guard columns or guard cartridges that were not a
'perfect match' to the column.

I would always recommend the use of a guard column. Same ID as the analytical column should be, poresize is depending on the MW composition. Same particle size should be. Good luck.

Yes, either will do the job. There is a theoretical possibility that the one with the larger pore size will delay some really enormous components of the mix that are not currently entering the particles of your column, but this is probably more a theoretical thing than a genuine practical concern. The other guard column, with smaller particles, will add a bit to your back-pressure, so if you have a method that's already pushing your instrument to the utter limit, and you're at that stage where you're anxiously watching the pressure climb, and shaving 50uL/min off the flow-rate because the method is teetering just below your upper pressure limit, you might prefer the large-particle guard column.
But both will offer considerable protection to your column, and neither should be disastrous for your chromatography.

Thanks everyone for comments. Guard columns aren't cheap but I will try to get both of them and see which one works better.