Blank Run

hi

that is column related issue

please conditioning the column and detector and check

Column : HP-5 30x 0.32x0.25,

Hi Krishna

Thanks,  I have conditioned the column on Friday for about 2-4 hrs with the above condition.  I believe both the column conditioning and the Detector conditioning is same.  Correct me if i am wrong.  I am using He as a carrier gas.  If anything needs to be changed in the above conditioning method please advise me.

Regards

Revathy

Hi Revathy,

It seems like the conditioning method is pretty good. However, you do not need to go maximum temperature all the time, generally; 30degC above the analysis method for Inlet/Detector/Column will also work unless you have high boiling compounds. Keeping the column temperature lower than the recommended will help to prolong the life of the column.

So, back to your original question. The 3 blanks shows that the residue compounds in the system are reducing which is good. If you set the Y-scale same as the first Blank, then you can see that the baseline is getting better (or you can try overlaying the 3 Blanks). If you still see the residue compounds even after much conditioning, then; you may want to clean the inlet with some MeOH or replace the Split Vent Trap Cartridge or clean the Split Vent copper tubing. These are some of the possible places where contamination can occur.

Hope these are helpful.

Regards,
Kelvin Tan

Hi,

First of all when you condition your column there is not need to go to the max temp, I would say that 10-15 over the max temperature used during your analysis should be enough. Hiting the max temp will shorten column life time, and will degrade the stationary phase which will appear in the next chromatograms.

Second point, use a temperature ramp as well once your gradient temp reached the max temp to go down to it's intial temp (10°C min), at least until the oven temp reached 120* this will also help to prevent stationary phase condensation during the oven cool down.

Actually what you see at the end of your chromatogram (Wavy baseline) is most likely condensated stationary phase from the previous runs coming out of your column...

Agree with everyone-'Bake' out (condition) the column, at ~25C below the Maximum Manufacture recommendation. it is probably best to not get to the max temp; as mentioned above. It will kill your column.

Question on proper way to condition a capillary column.   Do I have to disconnect the column from the detector to condition my column?   The column has been in use for several months. 

Thanks,

Tom