[mandytan]

Hi,

I am new to HPLC. Please help.

A procedure for the determination of Impurities A & B in a compound says to use  a 4.6 x 150mm x 3um column (stationary phase: octadecylsilyl silica gel).
The relative retention time with reference to the main peak is: -
1) about 0.2 for Impurity A
2) about 0.3 for Impurity B

If I use a 4.6 x 100mm x 2.7um column (same stationary phase),
will the relative retention times of Impurities A & B still be 0.2 & 0.3 with reference to the main peak?

I did a run using the shorter column with smaller particle size and the relative retention times with reference to the main peak are: -
1) Impurity A: 0.18
2) Impurity B:0.16

The resolution is good for the peaks.

Can you comment if the relative retention times are acceptable?