[lily_m]

hello everyone, i have a question if anyone can help please. is it possible to analyze for a substance which itself does not absorb in the ultraviolet region?

[azmanam]

Yes.  But you'll probably have to use an instrument other than the uv/vis spectrophotometer.  Is this a homework or practical question?  If practical, what compound and what other instruments are at your disposal?

[lily_m]

it was an analytical expt. to test the validity of Beer's law using a spectrophotometer. the solution we were using was methylene blue

[azmanam]

If all you're doing is a proof of concept lab, then may I suggest just switching analytes to something you know for sure will absorb in the uv region.

Although I'm surprised methylene blue doesn't absorb in the uv region.  It definitely absorbs in the visible region, though.  I'm not that up on my analytical techniques, though.  Maybe someone else has a better answer.

This website seems to indicate you should see a peak ~290 nm and ~675 nm.

http://ceeserver.cee.cornell.edu/mw24/Software/Spectrophotometer.htm

[lily_m]

thanks a million for your help