John,
     This is the method we use with our unit from CBG Biotech. Here's a simple method to determine the purity of your xylene: Prepare a calibration control mixture...1%...Add 5 ml. of absolute alcoholto 495 ml of xylene to establish this mixture. Since this procedure has a number of variables,the calibration mixture will be used as a standard for the person who has to perform
the procedure.By testing the standard mixture the person performing the procedure can see how a 1% contamination level reads, and can have confidence that all of the readings they obtain using this method are accurate.It is recommended that this mixture be tested at the beginning of each day.

TESTING PROCEDURE

1. To a clean,dry 100ml mixing cylinder graduate,add sufficient recovered xylene so that the bottom of the meniscus is alligned with  the edge of the 85 ml mark on the graduate.

2. Add water to the graduate until the bottom of the meniscus aligns with the top edge of the 100ml mark on the graduate.At this point, 15 ml of water will have been added to 85 ml of recovered xylene.

3.Stopper the graduate and gently invert the mixture. Allow the mixture to settle, making sure that all of the water settles to the bottom of the graduate. A small amount of water may remain clinging to the side of the graduate above the xylene/weater separation mark. This separation point should be near the 15 ml level of the graduate.(NOTE: Xylene floats on top of water).

4. Carefully inspect and record the point of separation between the xylene and water using the bottom of the meniscus as the separation point.

5. Subtract 15 ml from the quantity of water indicated in step 4. The remainder plus an additional 0.1 correction factor equals the percentage of recovered xylene impurities.

EXAMPLE: Xylene/Water separation pointis indicated to be15.5 ml(15.5-15)+0.1=0.6% impurities
Therefore, the recovered xylene is 99.4% pure.  Hope this helps.

Again this is taken from the CBG Biotech proceedure. I have to give them all the credit for making this such an easy procedure to follow.

Brian Fischer 
Histology SR. Tech
CHOMP
Monterey, Ca.

-----Original Message-----
From: John Spair [mailto:John.Spair@multicare.org]
Sent: Friday, June 14, 2002 1:38 PM
To: 'histonet@pathology.swmed.edu'
Subject: Alcohol and Xylene Recycling


I know many people are using stills these days to recycle alcohol and
xylene.  It's easy to check the alcohol with a hydrometer to determine
percent of the distilled product, but has anyone come up with a method of
checking the xylene for purity without having to send it somewhere for
analysis??? Thank you

John Spair,  System Manager
Pathology Services
LABORATORIES Northwest
MultiCare Health System
john.spair@multicare.org
253-403-6090


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