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StatLab Medical Products
April 8, 2014
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TECHNICALLY SPEAKING
HEMATOXYLIN CRYSTALS
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statlab.com
Technically Speaking, Volume 7
Hematoxylin Crystals
-Debbie Siena, HT(ASCP)QIHC
It is this time of year when you may notice that your Hematoxylin is sporting a bit of "bling"...crystals. You will usually be made aware of them upon picking up the container and giving it a bit of a shake. To explain crystals, we must first review how hematoxylin is made. As we all know, hematoxylin powder is useless as a dye for tissues, but also its oxidation product hematein cannot stain. Hematein being negatively charged is not able to bind to the negatively charged phosphoric acid groups of DNA and nucleoproteins, also known as chromatin. In order to stain tissues, we need to add another key ingredient- positively charged metallic ions (mordant). When Hematein is combined with a mordant, a dye lake is formed and the combination of the Hematein and the mordant is what stains our tissues.
The mordant that is used in Gill and Harris Hematoyxlin along with most of the other commercially prepared alum Hematoxylins is aluminum. The mordant in the Gill's hematoxylin is aluminum sulfate and it is this salt that is responsible for staining mucin. Harris Hematoxylin uses a more complex salt, aluminum ammonium sulfate, which results in its not staining mucin. Some hematoxylins such as Harris, have an overabundance of mordant (more than can combine with the hematein). When this is the situation then the excess mordant can actually form into the crystals at the bottom of the container but some stays in solution. However, when we have extremely cold weather such as we have had this year, then even more of the mordant can come out of solution and deposit on the bottom of the container.
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