I am responding to the postings regarding xylene substitutes - specifically the d-Limonenes.  I am the Project Manager for CBG Biotech's new clearing solvent, Formula 83, and perhaps I can shed some light on your questions.

First, it is important to note that d-Limonene solvents that are sold for histological use are petroleum-based, and they therefore cannot be poured down the drain (as per the EPA and the Clean Water Act).  Only solvents that are prepared entirely from plant and/or animal sources can be put down a drain. 

While adequate ventilation and proper handling are a must with solvents and chemicals, it is equally important to select solvents that OSHA has classified as non-toxic, thereby not requiring personal exposure limits.

As has been well demonstrated, it is the double bonds in benzenoid compounds that cause the toxicity of solvents like xylene and toluene.  Although the d-Limonene solvents are not as toxic as xylene, they still contain some double bonds.  The only safer alternatives are solvents with NO double bonds.

While there are quite a few safer solvents available, it then becomes important to find one that will perform up to your standards.  The aliphatic hydrocarbon solvents, although non-toxic, do not have a central cyclohexane ring, and will not offer the performance of solvents with a central cyclohexane ring.

Chemically, Formula 83 Clearing Solvent is a naphthenic solvent.  As such, it does not have the toxicity associated with double bonds, while its performance is excellent due to its central cyclohexane ring.  It outperforms xylene and other xylene substitutes in slide clarity, slide drying, paraffin-dissolving and personnel safety.  It does not harden tissue as xylene does, and it has better lipid extraction.  Additionally, most users notice a crisper, clearer nuclear detail with more vivid staining.

I would be happy to share more information with you.  I can be reached at the phone number or email address below.  

Best regards,

Judy Pariser
Project Manager
Email:  jpariser@cbgbiotech.com
Phone:  800-941-9484
Fax:  614-863-1676
Website:  www.cbgbiotech.com

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