Good day to everybody, I immediately expose my problem. I'm doing some measurements with the UV-vis spectroscopy and I'm having problems with the amines in the non visible region. This is what I do: put my amine in a quartz cuvette -> do the background (reference) -> analyze the same solution that I'm using as reference from 600nm to 200nm. The result that I should get should be a totally flat line, instead I get a negative absorption below 230nm which is a non-sense for Lambert-Beer law. What's the problem? Is there any resonance in the non visible region for the amines?