Maximum temperatures of packed columns – Liquid Phases

For my second post in this series, I would like to focus on liquid phases.  As you know, for packed columns, a liquid phase needs a solid support.  Combined, these are what makes the “packing”.  In most cases, it is the liquid phase which limits the packed column’s maximum temperature, and not the solid support.

Therefore, like my last post (Maximum temperatures of packed columns – Porous Polymers), I will make the following assumption:  The column’s maximum temperature is due to the liquid phase, and not the solid support, the column’s tubing, end plugs, fittings/adaptors and/or ferrules used for installation. If you have a packed column which includes non-metal tubing or end-plugs other than glass wool or metal, email us at support@restek.com.

In addition, if the solid support is not a DiatoSorb® diatomaceous earth, CarboBlack®, Chromosorb® P, or Res-Sil®, email us at support@restek.com

The table (below) contains the minimum and maximum temperatures of many of our liquid phases.  The link below has the same information in a format that is easier to read.

Packed Column Instruction Sheet   See page 2.

To summarize, the maximum temperature of a liquid phase on a solid support packed column is almost always determined by the liquid phase.  Keep watching for future posts on this topic.

 

Liquid Phases

5 Responses to “Maximum temperatures of packed columns – Liquid Phases”

  1. jaap says:

    Thanks Alan, please find here sme of my experiences:

    Please note that these temperatures are general maximum temperatures for the stationary phases. The PRACTICAL temperature that you can work with these phases is often MUCH lower. On packed columns there is a large amount of stationary phase, that can go up to 25-30%. This is 100-1000 times more then we use in a capillary. Column bleed is a direct function of the amount of stationary phase, meaning that the baseline will be impacted much more then we see with capillary columns. This is especially the case when sensitive detectors are used and one has to measure small peaks.

    For PRACTICAL operation in packed columns, I would take at least 75C lower temperature as listed in this overview. If just for conditioning, one can do that at higher temperatures, but do not cnnect the column with the detector. During this conditioning process, plug off the detector and connect the column after the high temperature conditioning.

  2. Alexandra says:

    Hello Alan (and jaap)

    In my experience, I’m working with a RT-Msieve 5A using a ECD detector; the maximum program temperature is 300°C, however we just let the oven maximum at 270°C because the nature of the sample that we are working with, my question is:
    Is it important to let the temperature so high or I can program the temperature below this value? My sample has SF6, How can I treat the column after a run with this kind of sample?

    Thanks a lot!

  3. Alan Sensue says:

    Thank you for your feedback Jaap. I totally agree that just because a maximum temperature is listed, that does not mean you should be taking your column to this temperature. I usually explain it to our customers this way – your automobile may be able to achieve a speed of 150 mph, but is it wise to drive at this speed? Even if safety was not an issue, driving your vehicle at its maximum speed for extended periods of time will likely cause it to fail much quicker than if driven a lower speed. I usually suggest keeping the column at least 25°C to 50°C below the maximum temperature listed, and even then, only take it to this lower temperature if absolutely needed. Alan

  4. Alan Sensue says:

    Hello Alexandra. Thank you for reading my post. I plan to discuss maximum temperatures of molecular sieves in a future post, but since you have asked, I will do my best to provide you an answer. Zeolite molecular sieves are, in many aspects, rather unique compared to non-molecular sieve columns. Personally I would keep the column at 150°C (with carrier gas flowing through it) when not in use instead of the 270°C you mentioned. but you know more about your samples than I do. However, you mentioned SF6 which should have no retention on a molecular sieve 5A (it is too large to fit into the pores), so unless your sample contained some other gases, I do not see the need to take or keep your column at 275°C. Regards, Alan.

  5. Jaap de zeeuw says:

    Indeed, SF6 does not fit inside the pores. Its only retained by the outside of the particles. For capillaries it probably elutes almost together with helium.
    Like Alan shared, if other matrix components are there, like water or C2-C5 , you need to condition periodically to keep the retention. 150 C seems also very practical to me. Why use 300C? What do you need to elute from the molsieve?

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