Chromatography Forum

I'm using a gradient separation and my mobile phases are as follows:

A = 0.1% HClO4 in water
B = 0.1% HClO4 in a mixture of MeOH/ACN

I'm monitoring 220 nm.

My question/problem is this: Is anyone aware of an incompatibility with perchloric acid and MeOH/ACN? It appears that the UV absorption of my "B" mobile phase increases over a relatively short period of time (< 24 hours). This affects the sensitivity of the method and also my mood.

Thanks in advance.

Maybe you are forming acetic acid, which would also explain the vinegary mood...

Uwe is probably right. If you have a ternary pump, put aqueous 1% HClO4 in the third channel, and run a constant 10%C in your gradient.

I'll give it a try. Thanks for the suggestion.

JD