Questions about 13-micron Shodex HT806M GPC columns

Record: 632

Category: Specifications
Product: HT
Sample:

Question
We have been using your HT803, HT804, HT805 and HT806 columns in our GPC analysis for polyethylene.

Recently, we purchased your HT806M (4 columns) and operated these columns at 140 o C with a flow rate of 1.0 mL/min. As requested by our client, there is a requirement for using your HT806M columns at 150 o C with a flow rate of 0.6 to 1.0 mL/min. Based on the column specification provided in the operation manual, the normal usable temperature for the Shodex HT806M columns is 140 o C and the maximum usable temperature is 150 o C. I would like to check with you to see if it is safe if we operate HT806M columns at 150 o C. Our major concern is the risk to our GPC instrument due to possible degradation of column packing material at a higher temperature, since significant spikes were observed for the light scattering detector (LSD) response at 15 degree when the columns were operate at 140 o C. It was confirmed those spikes were coming from the column packing material (since there are almost no spikes observed for another set of columns, PL Mixed B LS, under the same operating conditions). The solvent we used is 1,2,4-trichlorobene (TCB), and the detectors are a refractive index (RI) detector, a viscometer (four capillaries) and a dual-angle light scattering detector (Precision Detectors Model 2040).

Answer
Analysis at 150 oC is under our guaranteed use, so it should not be a problem.
Although we are afraid, but we have heard about the “shedding” problem in the past.
It is not a result of gel degradation, but somehow related to original condition of the gel.
This will be reduced after a period of cleaning process.
How long have you been operating the column at 140 oC?
I would suggest you to run the mobile phase (or toluene) for a while at 150 oC without connecting to the detector.
You should start to see the baseline noise decrease.

 
 
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