Chromatography Forum

Hi

Just curious

Does all the column manufactures does the analytical HPLC column packing by same method..??

No, C18 columns, for example, from different manufacturers are quite different. The difference results in small changes in column selectivity. For example, some analytes may be better resolved on a particular C18; some analytes may have less tailing; retention times will be slightly different....

I hope this helps you out.

Shaun

If you were asking "do they all pack the columns the same way?", the answer again, is "no".

A couple of recent threads elaborate on the question:

http://www.sepsci.com/chromforum/viewtopic.php?t=6876
http://www.sepsci.com/chromforum/viewtopic.php?t=6776

If you look at this from the top of Mount Everest, the answer is yes: all small particle columns are packed by a method where a slurry of the particles is pushed into the column at high pressure.

If you want to look at the details: absolutely not. All packing processes are proprietary to the manufacturers, and (usually) the methods do not leave the plant. I have to say though that I found in the late 1980's a packing procedure in a Japanese company that was a carbon copy of a mid 1970's procedure created by a US manufacturer. It was impossible that both procedures could have been independent inventions. So much for industrial secrets and proprietary technology...

rick1112,

Commercial companies who pack columns guard their processes tightly. However, that doesn't stop research activities in this area. Be warn though; the wet slurry packing procedure is very dangerous, as mentioned above.

Check out the publication literature from Prof. Guiochon, R.A. Shalliker, and V. Wong. As Uwe and Tom said, packing column is an art. One just need to experiment....one of my previous in-roads into this kind of research took 1.5 years before I was comfortable enough that I was able to pack columns more consistently.

Hope this helps.

Hi

Does this mean that a column with same chemistry..(Lets say C18) from different manufactures gives different peak profile (in terms of impurity resolved, LOD, peak shape etc.) because of the different column packing or is the reason something else??

The chemistry of the particle itself (polarity, carbon load, size, shape, etc.) would usually be a larger difference between "similar" columns from different companies, greater than the way they physically pack that into a column.

Let me clarify further what the Consumer Products Guy has said.

Peak shapes very certainly depend on the packing method and the test method (and the specifications, of course), which are different between different manufacturers. However, a C18 is not a C18, and the statement above applies only, if the same particle is packed by different manufacturers.

In general, there are much larger differences between different C18s then there are between different packing methods. Think of it in the following way: a packing method can only influence the physical parameters of a column, plate count, asymmetry, backpressure, while the chemical nature of the packing determines everything that we care about most: retention times and selectivity.

This is the reason why you get different types of C18s from the same manufacturer: the selectivity differences have been designed into the nature of the surface.

There is a small communications problem here. Some people use "column packing" as synonym for "stationary phase." Some people use "column packing" for the process of filling the tube. In reading the posts, I can't always tell which definition is assumed. Rick1112, did you mean the first or second meaning?