Chromatography Forum

Hi, all -

I have a uv/vis spec method for quantitation at 690 nm. (We're in discovery, so the method hasn't been validated at all - just linearity.) My samples are supposed to turn green (just as my standards do). Some samples did NOT turn green, but still gave a reading. Is this okay? I figure they're reading absorbance at a given wavelength, so even though the color was different from the standards, it still is a valid.

But I don't know much about the technique. Any help, or direction to websites, etc, would be appreciated!

EM

If it was not green, because the concentration was too low to see with the bare eye you might be ok. If it was not green because the pH had shifted the wavelength or that you have a different material, than it is not ok. Also, if you see a differnt color it could be that you have a mixture. You could be ok if you separate this other material or if the spectrum doesn´t overlap. This is one reason for doing calibrations and other tests: To find out about what´s going on.

HW-

Thanks for the pH tip! That's the path I'm heading down, and it looks promising.

EM