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which factors effect relative retention time
Posted: Thu May 06, 2010 9:24 am
by qinyong-023
In order to locate some interested solvents, I performed the method described in ChP 2010 version, non-polar column, maintain at 40℃ for 8 min, then with 8℃/min to 120℃, maintain 10min. In this method, I use a DB-1 column with different ID and film described in ChP. But the result is disappointed. It is hard to locate the solvents by their PARTs. PART=(tR-t0 ) /( t’R-to), where to is the retention time of Methane, t’R is the retention time of Butanone, tR is the retention time of interested solvent. Would you kind to explain which factors effect PART and how they affect it . Thanks
Posted: Thu May 06, 2010 11:25 am
by Don_Hilton
When you change column dimensions, compounds will elute more quickly from a column with a narrower diameter and from a column with a thinner stationary phase.
You must also take into consideration the linear velocity of the mobile phase. If you have operated the column at the same pressures as used for a column with different dimensions, the peak shape may change, degrading resolution and making it difficult to find some peaks.
The temperature ramp is set to help resolve peaks at the rates at which they elute from the original column. If you have changed column diameter, expect to need to change the temperature profile as well.
Posted: Thu May 06, 2010 11:53 am
by Peter Apps
The problem might lie with the retention time of methane - how are you measuring this ?
Peter