effect of “high Temperatureâ€

[rick1112]

Hi

What is the effect of “high Temperatureâ€

[unmgvar]

let's just say that in general for standard column above 45 degrees you start to damage them, most cannot go above 60 and will "die" in the matter of several hours or a day's work.
look at vendor specs for more details

[rick1112]

hi unmgvar

i was curious why would they die when the temperature go up ??
a look in catalogs also shows that different columns or bonded phase have different limits...
e.g. Zorbax SB C8 has a temperature limit of 80oC but Zorbax SB C18 has a limit of 90oC...SEC columns comes with still lower limits...why??

[HW Mueller]

Pretty much for the same reason that we humans come with a temp. limit.

[mohan_2008]

It all depends on the bonding chemistry, bonding density and endcapping etc.

High temperature is found to have an indirect effect on the column life. It can act like a catalyst in enhancing either acid hydrolysis of your siloxane bond at low pH - or solubilize the silica at the high pH.

Manufacturers experiment the effect of temperature on their columns with accelerated temperature conditions to determine their temperature stability at preferably neutral pH.

[Jade.Barker]

Temp tollerances can vary a lot. If you have a column catalog laying around, crack it open. Mine is practically a reference book to me.

My exp:
My old lab was doing testing Ethanol Fermentation samples. The temp really effected the separation. The column oven got turned off (while I was away) and returned to room temp (From 70 degrees down to 24). The Lactic Acid peak slid right into my Glycerol peak. It was so bad It started losing identity!

I have heard that RI detectors are very sensitive to temp changes too. I guess I would follow the manf. recomendations for column conditions.

Good Luck!

[lmh]

... but for those who work in an environment where money is tight, but regulators don't lurk behind every filing cabinet, do consider checking that your column has been damaged by high temperature before throwing it away.

We had a strange fault on an hplc column oven that meant it ran all the samples at the correct temperature, and then just turned the heater on, uncontrolled, for the rest of the night. It reached about 70-80 degrees if I remember, and did it three times in total. The same Luna C18 column was in the oven each time, and seemed unaffected compared to a similar column that we didn't abuse. Of course, so far as we can make out, the temperature disaster would have been in non-flowing 70% acetonitrile, 30% water, rather than flowing dilute formic acid, which would probably be substantially worse for the column.

[rick1112]

hi everyone..

one of my question still remains...why the difference in temperature limit between Zorbax SBC8 (which has temp limit of 80oC) and Zorbax SB C18 (temp limit of 90oC)

also Temp tolerance of Zorbax sable bond (SB) is higher than other Zorbax columns such as Zorbax extented ...why so??

[tom jupille]

one of my question still remains...why the difference in temperature limit between Zorbax SBC8 (which has temp limit of 80oC) and Zorbax SB C18 (temp limit of 90oC)

At low pH, bonded phase is cleaved by acid catalyzed hydrolysis of the silyl ether linkage. These columns are arguably more stable than would be expected based on the stability of that bond, and one explanation is that the hydrophobicity of the bonded phase tends to keep it in place long enough for the bond to re-form (most of the time!). C8 is less hydrophobic than C18, and so less stable in a high temperature / low pH environment.

also Temp tolerance of Zorbax sable bond (SB) is higher than other Zorbax columns such as Zorbax extented ...why so??

Contact your local Agilent agent and ask for their literature on "sterically protected" bonded phases. All will be explained there.