Sciencemadness Discussion Board

Fluorescence with dansyl chloride

woelen - 18-10-2007 at 12:56

I received a small amount of dansyl chloride (1 gram). The solid I have is a light yellow powder, which reacts with water, giving a deep yellow compound. I have no real application for this chemical, but on Internet I read that it is used as a fluorescent indicator in biochemistry.

How is this compound actually used? Is there anything interesting (e.g. fluorescence experiments) which I could do with this compound in home-chemistry with other easy to obtain chemicals?

Ozone - 18-10-2007 at 13:23

I use it to label amino acids (from protein hydrolized in 1:1 HCl at 120°C, overnight). The mixture is neutralized with NaHCO3 and rendered alkaline to pH ~8. To this is added 20mM Dansyl Chloride in (my case) acetonitrile. The sample is sealed and heated at 80°C for ~20min and separated using HPLC.

The derivatives are highly fluorescent, and provide extreme sensitivity (which is good since protein isolates are hard to come by and usually very small). Ex 330nm Em. 560nm.

There is also a very nice absorbance ~245nm which can be used, but it is far less sensitive (and sadly, what I am limited to with a DAD).

Take an amino compound and mix in some DANSYL then compare with a control under a cheapo black light. Quite nice:). The control will be light blue and the positive test, yellow (this is somewhat variable depending on the amino acid).

Cheers,

O3