Peak in blank

[ym3142]

That's fine, Marian.
So you flow 1ml/min, length 10 cm, and void time 1 min,
my estimation found you column ID is 4.2 mm, is this correct?

Have a great day,

[Uwe Neue]

Are you using plastic vials or glass vials?

[ym3142]

what will happen if you continuously inject 10 times of 200ul MeOH? If the peak shrinked, your syetems (both, coincidently) were contaminated.

Good Luck,

[max_planck]

Your problem is called solvent front.

[ym3142]

Marian:
have you solved your problem?
if you did, what is the root cause?
thanks,