Methods developed on the 4um
Cogent™ line of HPLC column products can be readily adapted with near-UHPLC Cogent
2.o™ phases. In this blog, we have a method for forced degradation of
atorvastatin (Lipitor®). The gradient separates the main API (atorvastatin)
from its more hydrophobic lactone degradant. The retention is comparable between the 2.2um
column (Figure A) and 4um column (Figure B). However, efficiency is higher on
the 2.2um phase which is a significant advantage for the user. With higher
efficiency, you can obtain better resolution from closely eluting peaks. Also,
you will get higher sensitivity due to the increased peak height. The
efficiencies for the API were 88,420 plates/meter for the 4um column but 134,800
plates/meter for the 2.o™ phase.
In this application, a standard HPLC (Agilent HP
1100) was used in both cases. With near-UHPLC columns, you don’t need a full
UHPLC system to obtain the benefits of efficiency, resolution, and sensitivity.
This is an important aspect since many QC laboratories don’t use UHPLC
instrumentation in their routine assays. The only thing to keep in mind is that
your column pressure will be higher and you should not exceed 120 bar on a
regular HPLC system.
1 - Atorvastatin
2 - Atorvastatin Lactone
