Difference between 10% and 20 % Column

[E11022]

What are the difference(s) between 10% TCEP on Chromosorb W AW DMDCS,80/100 and 20% TCEP on Chromosorb P AW DMDCS 80/100 column?

My colleague claimed that 10% TCEP column is not good on seperation process compare to 20%.


thank you.

Regards,
Alice

[rb6banjo]

Don't you suppose that it's like nearly everything else, "it depends on your application". Column choice is always linked to your desire to separate certain analytes. You find one that does the job for you and your sample(s). I analyze some CO2. A wax is worthless for the straight-chained hydrocarbons of interest in that matrix so we use a nonpolar phase for those. However, to separate all of the xylene isomers the wax is essential.

All columns have some merit. It all depends on the application. If one works for you, go with it!

[Don_Hilton]

Note that besides differences in loading, you have a difference in support (Chromosorb W vs. Chromosorb P) as well. While there is quite a bit of loading, the support may (or may not) make a difference in what you are doing.

[E11022]

Back to 8 years ago, we used 10% TCEP on Chromosorb W AW DMDCS,80/100 to seperate PDEB in xylene product and it works perfectly.
3 years ago, Senior changed the column to 20% TCEP on Chromosorb P AW DMDCS 80/100 column and seperation worked fine too.(the senior resigned)

Now, i reverted back to 10% TCEP on Chromosorb W AW DMDCS,80/100 and i am unable to seperate my product in the same settings, unless i increase/double my cycle time, then i managed to get all peaks.

Hence, i wish to know the difference in these 2 columns. as i am not so understand on columns' material.

Thank you

[Don_Hilton]

It looks like you have columns loaded with 1,2,3-tris[2-cyanoethoxy]propane. The loading is different on each. The solid supports have different treatments, which can affect the separation somewhat, but from your having used both with success, any affect should be minimal.

So, as you have gone back to the 10% loaded column, have you acquired a new column - or have you taken an old column and put it back into the isntrument? And if it was a old column, how was it stored? Did you take any steps to condition the new column after installation? If new, did you pack it your self or purchase it as a packed column?

[E11022]

We replaced a new packed column which i bought from Restek (10% TCEP on Chromosorb W AW DMDCS,80/100).
We let the carrier gas flow only in the GC for 1 day with the new column.
But after that, i was unable to obtain the peak.

We reverted back to 20% packed column which was just being removed the other day, and then able to obtain the peak.

Usually, we put the old column into a zip bag.

The reason we decided to change the column because ghost peak appeared and fine tuning didnt help to remove it at all.

i am actually suspecting the new column is not meeting my specs.

I need to make a decision whether to stick to the original column design which is 10% or change to new column specs which is 20%.

[Don_Hilton]

Are the dimensions of the new column from Restek (length, diameter, particle size) the same as what was used before? And is the the same column material (glass/stainless steel)? And are the operating conditions exactly the same a when a column of the same type was used in the past (temperature conditions and flow through the column)?

And are you able to see any kind of a peak at all with the new column - such as an injection of pentane or butane (assuming a detector that could see these - like FID)?