problem with vitamin A analysis

[khalidrauf]

i am working on the HPLC analysis of fat soluble anti oxidant vitamins (Vit A and E) in biological samples. during working on serum sample i found an extra peak preceding the vitamin A peak. I am not sure abt the nature of that peak so please help me in this regards. How these peak can be resolved and separated. i am using pure methanol as mobile phase with flow rate 2 ml/min, uv detector at 292 nm, column kromasil 100 5 micron 150x4.6 mm. With thanx

[tom jupille]

Difficult to answer without more information:

What are the k' values of the two peaks?

What kind of efficiency (plate number) are you seeing?