Re: [Histonet] Alcian Blue Quality Control

From:Rene J Buesa

You cannot go much with the wave length absorption, because that depends on the color (molecular struicture) and not with the contents. You would have to have a calibration curve to determine absorption coefficient versus concentration, and that is where you get again to your concentration incognita.
  Do you still have some amount of your original dye? If you do, weight a small amount. Weight the same amount of your actual powder and dissolve both amounts in equal and small amounts of distilled water. Then compare their extintion coefficients at the the same wave length. You will not be able to quantify either concentration but you will find out which is stronger. You could even know how much stronger one is to respect (as a ratio between both extinsion coefficients) to the other and adjust your amounts for your working solutions accordingly. In that way you can assure equally intense staining solutions always, even if you do not know the dye contents in neither.
  All chemical companies are very tight-lip about their "proprietary" products.
  René J.

JR R  wrote:
I have used Alcian Blue 8GX from Sigma for years with pretty good results. But I have had some variations in staining lately and noticed that the powder in the new lot isn't quite as dark as the previous lot. Finally, I noticed that Sigma only guarantees the product to be have a dye content of "at least" 50%.

I would like to try to assay the dye content myself, so I could make my solutions to the sane strength every time. Sigma says they don't know hw, they have no idea what the molar extinction coefficient of the compound is, and they refuse to tell me the name of the lab that does the QC.

The only thing I know is that it has a major absorbance peak at 610 nm.

Oh, rumor says there was an aticle about it in Histochemie back in 1972.

Any ideas?

Jerry Ricks
Research Scientist
University of Washington
Department of Pathology

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