Chromatography Forum

I'm a chemistry graduate student in an environmental engineering lab tasked with replacing the column on one of our lab's HPLCs. I'm the first chemist in the lab, and therefore all the analytical instrumentation has fallen to my care. This is likely a good thing, as prior to my arrival, they had been using the same column for 8 years (~10-50 inj/week), for environmental samples, with no precolumn, and no degassing of the mobile phase. They complained to me that it is not separating correctly (or at all) anymore.
Anyone shocked?
No? Me either.

Point being:
These guys are not chemists
They are not fond of change
They expect the next column to "last as long" (which, of course, would be presupposing that this one did last that long)

My problem:
I need to decide on a replacement column, and I want to improve on what they use, but I'm not sure how to weigh my options.
I was hoping someone with more experience might have some advice.

What we use now:
NovaPak C18
50:50 MeOH:H2O + 0.1% Phosphate
Detecting phenols, chlorophenols, chloroethenes, etc.

Now, I could just buy another NovaPak, but is it worth it to upgrade to something newer with higher purity, etc.?

I'm deciding between the following three columns (all Waters):
OPTION 1 NovaPak C18 3.9x150,
OPTION 2 SunFire C18 3.5um 3.0x150mm,
OPTION 3 XBridge C18 3.5um 3.0x150mm

Pros for OPTION 1
- cheaper
- less method development necessary
- they're already used to it

Cons for OPTION 1
- low purity silica
- pretty unimpressive peak shapes as far as I've seen with our current one
- I think we can achieve better sensitivity with something else
- 30 year old technology (isn't there something better?)

Pros for OPTION 2
- mid line cost
- high purity silica
- higher hydrophobicity (should this be a con?)

Cons for OPTION 2
- a lot more method development
- longer retention times?
- Not as similar to the NovaPak as the XBridge

Pros for OPTION 3
- high purity silica
- tolerance for higher pH's (I guarantee no one in my lab checks pH before running things)
- hybrid technology, better resolution and sensitivity

Cons for OPTION 3
- a lot more method development
- most expensive of the options (50% more than NovaPak)

As you probably have observed, I've spent quite a bit of time thinking about this, and the truth is, I just need someone who's done this enough to help me make this decision.

Can anyone offer advise?

Congratulations on your new position. If the people in your lab do not know chromatography, it will up to you to educate them. Maybe half an hour of seminar on the basic principles, difference between different types of reversed phase column and chemistries (type A/type B silica, mono/polyfunctional bonding etc) and maybe talking a little bit about column lifespan , will establish you as the expert there and people will probably accept easier your recommendations.

I do not see why latest generation columns will require singinficantly more method development. It might very well be that whatever was separated with the previous packing, might be separated with a new generation one without need to change (almost) anything. As a bonus you might achieve more resolution... I would go with the Xbridge and blame gas prices for the 50% premium (just kidding for the latter).

Probably their HPLC system has not being optimized for void volumes so I would probably aim for a 4.6 mm ID column (i.e. higher flow rates). A pre-column sounds like a very good idea as well...

I would stick with the older technology in your case. They got eight years out of the old one. It has proven itself to work for what you need and has long life with all the potential abuse (no guard column, un-checked pH).

Does anyone actually know when the chromatography started to decline? Do you have any kind of system suitability parameters (resolution, tailing factor, theoretical plates)? If not you may want to consider it and start tracking your next column performance so that it does not fade to the point where peaks are not resolved.

To set some system suitability requirements it would help if you can look at all of your historical data. Do you always use the same sample preparations and mobile phase? If not you may want to set up different system suitability requirements per test.

Simce you are not sure it would be advisable instead of thinking about this to check all the recent lit on phenol HPLC and then rethink and try to understand why people did what (a good backgrounf in chromatography is in order here). Why would anybody in their right mind voluntarily forego other people´s experience? One caution on this, though: You saw that some people may not know what they are doing, I have seen some report or even publish, nevertheless.

Scottythree,

From what I understand, the people think that they got 8 years out of it. Maybe the column has started giving unacceptable results (for our criteria) after a year or so...

Kostas,
You may be correct. This is why I suggested looking at historical data and to try to assign some system suitability requirements. I just thought it may be easier then proving a new style of column.

My opinion is to stick with the column that has worked for eight years and maybe some 10 000 injections.

If I wanted to improve the method(s) for one reason or another, I would use a modern column for the development of the "new and improved" method(s).