HPLC and mixed mode columns

[Analisis]

Hello,

Until this time I know mostly about reverse phase chromatography. I have used a little normal phase. Well I have a problem choising a column for the analysius of Paraquat in formulations. This is not a trace analysis is simply Quality Control analysis. I have read that one column to use is the Waters column μBondapak C18 Column, 10 μm, 3.9 x 300 mm, but also have advise to use one of the following columns:
Cadenza 5CL-C18 / 250 x 4mm, 5um from Imtakt and
Scherzo 5SM-C18 / 5SM046 (250x4.6mm, 5um) also from Imtakt

The last one is a mixed mode column you can see a brochure of this columns at http://www.imtaktusa.com/products/

What advantage has a multimode column over the column from Waters for example?

Thank you for the advise.

[Uwe Neue]

While microBondapak C18 is a product of my company, I advise you that you should use a newer column. A good choice is Atlantis T3 from Waters, which has similar reversed-phase retention properties as Ye Olde Bondapak, but a range of improved stability features.

MicroBondapak C18 was designed in 1973, i.e. the product is 37 years old. It was highly innovative at the time of its design, and many people attempted unsuccessfully to copy the product. It is also used in many older applications. However, column technology has improved. (In 1973, neither PCs nor pocket calculators existed!)

[strobbia]

Hi Analisis

You have probably already chosen your column but if not, I have been developing a method for paraquat and diquat analysis using a bare silica column using HILIC.
This has worked reasonably well (and doesn't require ion pairing reagents) so you may want to consider that.


Stephen

[SIELC_Tech]

Here is application for paraquat and diquat from "pioneers" of mixed-mode

http://www.sielc.com/application_180.html

Almost any C18 column will produce tailing (even well end-capped column)

[Analisis]

Hello Strobbia

You have probably already chosen your column but if not, I have been developing a method for paraquat and diquat analysis using a bare silica column using HILIC.
This has worked reasonably well (and doesn't require ion pairing reagents) so you may want to consider that.

Thank you for your help. We have bought the Imtakt Scherzo column 5SM-C18 (250x4.6mm, 5um). Can you please give me some tips on your development.

Thank you

Analisis

[juddc]

I understand that I'm late to the party, but if I had to develop a method for this material and I wasn't going to use an MS, I'd probably just go with a high quality reversed phase column (Symmetry, Inertsil, Luna, whatever...) and a perfluorinated carboxylic acid ion pairing agent (TFA, HFBA, etc...). The resultant method would be fairly rugged and straightforward.

Mixed mode columns are great, but I think that their best use with with an MS. In my experience, they're just not as robust as a plain old good quality endcapped reverded phase column. I know that ion pairing has its issues, but there's no reason to be phobic if you understand the issues and work within the limits of the technique. Buy good quality chemicals, keep your MP fresh, and you should be OK.