I've been thrown back into the world of HPLC after I thought I'd left it behind 8 years ago!
The company I work for has 1 HPLC system and the two methods used on it were transferred from an external company. It is used for determine levels of glutaraldehyde and formaldehyde in separate solutions.
We use DNPH to derivatise the glutaraldehyde and formaldehyde in the sample solutions and are sometimes finding that the concentration increases over the course of the run ~ 6-8 hours.
Does anyone have any experience of this? What can we look at to stop this happening?
Mobile phase: acetonitrile and water
Gradient elution with on-line mixing
Column: C8, 4.6 x 150mm
Diluent: 50:50 acetonitrile and water