Chromatography Forum

hi
one of my colleague just developed a quantification method in UPLC ona Guard column (Agilent Zorbax 300-SB-C18,2.1X 12.5 mm).. although the method has its advantage of being short (Approx 6 min)..i would like to know if u all support this view of using (or developing method ) a guard column for quantification method..?

As long as he has enough retention, it is still acceptable in my view. The only downside I see is that the effects of column aging/junk accumulation might be much more pronounced in a very short column. So it will also depend on his matrix, mobile phase etc...

I don't see any major problems using guard columns for analytical separations (except the one pointed out by Kostas). You might want to ask the manufacturer if and how they are QC'd though.

The guard cartridges we use most times do not have a specific identifier on them such as a serial number. And our Alltech All-guard cartridges don't even have a part number on them or any description of what the cartridge is packed with, only the outer box for the 3 cartridges states that. Is that nuts or what?

Our stainless steel guard columns have the stationary phase etched onto the tube (e.g. PRP-1, PRP-X100). No serial number.

Our PEEK cartridges have no identifier at all, only on the box. There is not enough space to effectively label those.

Rick,

Do you see any additional peaks – other than the one corresponding to the target analyte?
Maybe there’s no need for any column at all?

Best Regards

hi

well I have been cautious about developing the method in a guard column as guard column may not have gone through same qualification experiments as HPLC columns( hope I am right about this..)….

Strange, we have had a large number of chains in which people ask whether they can go ahead and use methods which obviously don´t work, while here the question seems to be whether one should use a method which works.
There are millions of succesful uses of SPE (many have similar dimensions to a guard) for cleaning up samples, what if the cleaning up is sufficient for a quantitation, or whatever?
Here is an example of what I have done for over 10 years: The radio-iodination (I-123) of methyltyrosine yields mono and diiodinated species + small amounts of other stuff. A Waters Sep-Pak (?) C-18 cartridge of an early generation is used to separate the monoiodo from the diiodo, and huge amounts of excess methyltyrosine. It does a good job on that. A check with a 250x4.6mm column showed that there still is more methyltyrosine than monoiodotyrosine present + traces of other radioactivity, no diiodo. This monoiodo- is used to show fast growing human brain tumors. It was decided that the faster cartridge cleanup method was sufficient and was to be preferred.