Monday, May 4, 2009

Testing Liquids with the Computrac Vapor Pro, GREEN Karl Fischer Alternative


The Vapor Pro® has a programmable bottle purge function to evacuate any ambient air trapped in the vial by running dry air or nitrogen through the vial before the test begins. However, some liquids are very susceptible to giving up moisture at very low temperatures. So how can you test a liquid accurately if it is losing moisture before you even start a test? The Vapor Pro® pre-bottle purge method is the answer. By pre-purging the vial you are able to inject the liquid sample into a dry environment without worry of loosing moisture to the atmosphere or the Vapor Pro® standard bottle purge. In addition to using this method you can program the instrument with a zero bottle purge time and start the test right away. Follow the below procedure to pre-purge your vials and see if this will help in your accuracy and repeatability.

Vapor Pro Pre Bottle Purge Procedure

•Place empty vial, with septa & cap securely fastened, into Vapor Pro® carriage
•Choose any program (ideally the program you will subsequently use to test a sample)
•Press start and enter in 0.00 weight
•Test should take a couple minutes. Once test is done, be careful…the vial will be hot.
•You can purge multiple bottles for later use. The bottle purge is good for about 24hrs.
•Do not remove cap and septa from bottle

Once the vial has cooled down and you have a sample ready to test, tare the entire vial on a balance. Once the tare is complete, use a syringe with needle and pierce the septa close to the edge of the cap (don’t pierce the middle of the septa) and place about 10 drops of sample into the vial. Place the vial back on the balance to obtain the start weight. Choose correct program, place the vial into the Vapor Pro® carriage, press start, and follow the on screen instructions.

If you use this procedure to test your sample be sure you are using a zero purge.

Please call us for more information!

Kris Vancers
Account Development Specialist
800.528.7411 x1655 • 602.281.1655

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