DNA Engine Tetrad 2 Thermal Cycler Operations Manual
4-14 Tech Support: 1-800-4BIORAD • 1-800-424-6723 • www.bio-rad.com
The Solution
1. Substitute the low-energy beta emitter
33
P in cycle sequencing.
33
P nucleotides
are not subject to the same kind of chemical breakdown as
35
S nucleotides, and
they have not been associated with volatile breakdown products.
2. If
35
S must be used, three things will help control contamination: an oil overlay
inside the tubes, mineral oil in the thermal cycler outside the tubes, and use of
thick-walled 0.5 ml tubes. Always run
35
S thermal cycling reactions in a fume
hood, and be aware that vessels may be contaminated on the outside after
thermal cycling. Please be certain that you are using the appropriate detection
methods and cleaning procedures for this isotope. Consult your radiation safety
officer for his or her recommendations.
If mild cleaning agents do not remove radioactivity, harsher cleaners may be used
occasionally and carefully. Users have suggested the detergent PCC-54 (Pierce
Chemical Co., Rockford, Illinois; Pierce Eurochemie B.V., Holland), Micro Cleaning
Solution (Cole-Parmer, Niles, Illinois), and Dow Bathroom Cleaner (available in
supermarkets).
Caution: Harsh cleaning agents (such as those above) are corrosive and must be
thoroughly rinsed away within a few minutes of application. They can eat
away the surface finish of the blocks.
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