RE: [Histonet] Wax removal incomplete
I often wondered about this due to the "plastic "polymers added to the different types of paraffins. Perhaps it's these "polymers" that are not being removed with the typical solvents.
Thanks John !
Mark A. Lewis B.A., H.T.(ASCP)
Thermo Electron Corporation
171 Industry Drive
Pittsburgh, Pa. 15275
From: email@example.com [mailto:firstname.lastname@example.org] On Behalf Of John Kiernan
Sent: Monday, February 14, 2005 1:40 PM
Subject: [Histonet] Wax removal incomplete
A recent publication from Ireland shows (by laser confocal
Raman microspectroscopy, no less) that wax removal from
sections, as usually practised, is always incomplete.
The authors were able to remove all the paraffin, however,
with hexane. The other things they tried were xylene,
"histoclear" followed by hot antigen retrieval, and
"trilogy" (a product that combines dewaxing and retrieval
- ? a solvent-detergent mixture). All three failed to
remove all the wax, even with repeated, prolonged
For hexane, 18 hours were needed for complete was removal.
The investigators found that the residual paraffin
seriously interfered with the Raman spectra of
rehydrated sections. They are investigating the Raman
technique (which they explain fairly simply) for early
diagnosis of tumours. They also claim stronger
immunostaining after dewaxing in hexane (18h) than after
xylene (18h). They tested only one antibody (to
and the pair of photos doesn't make the point very
They authors also state that hexane is less toxic than
xylene. I can add that the least expensive n-hexane is
a little cheaper than xylenes (mixed isomers) in one
catalogue checked. Both solvents are flammable, and
n-hexane (BP 69C) is more volatile than xylene. Both
solvents are miscible with 100% alcohol.
The reference is:
O'Faolain E et 6 al. (2005) Raman spectroscopic evaluation
of efficacy of current paraffin wax section dewaxing
agents. J. Histochem. Cytochem. 53(1): 121-129.
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London, Canada N6A 5C1
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