Appendix 4-B: Safety Warning Regarding Use Of - BIO RAD PTC-200 Operation Manual

DNA Engine Operations Manual
Appendix 4-B
Some researchers have experienced a problem with radioactive contamination when
using 35 S in thermal cyclers. This problem has occurred with all types of reaction vessels.
The Problem
When 35 S nucleotides are thermally cycled, a volatile chemical breakdown product
forms, probably SO
sample block of a thermal cycler, and possibly the air in the laboratory.
Contamination has been reported with microassay plates, 0.2 ml tubes, and 0.5 ml
tubes.
96-Well Polycarbonate Microplates
These microplates present the largest risk of contamination. Polycarbonate is some-
what permeable both to water and the
exacerbated when polycarbonate plates are held at high temperatures for long
periods of time, or when the plates are sealed for oil-free thermal cycling.
0.2 ml Polypropylene Tubes and 96-Well Polypropylene Microplates
These tubes are manufactured with very thin walls to enhance thermal transfer. The
thin walls are somewhat fragile and can "craze" or develop small cracks when sub-
ject to mechanical stress. Undamaged thin polypropylene tubes may also be
somewhat permeable to the
reports of
during thermal cycling. No data are yet available on radioactive contamination with
polypropylene microplates.
0.5 ml Polypropylene Tubes
Contamination problems are rarer with this type of tube, but instances have been
reported.
The Solution
1. Substitute the low-energy beta emitter
are not subject to the same kind of chemical breakdown as
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 0.5ml tubes. Always run
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.
4-12 Tech Support: 1-800-4BIORAD • 1-800-424-6723 • www.bio-rad.com
. This product can escape the vessel and contaminate the
2
35 S breakdown product. Either way, there have been
35 S passing through the walls of 0.2 ml tubes of several different brands
Safety Warning Regarding Use of
35 S Nucleotides
35 S breakdown product. This problem is
33 P in cycle sequencing.
35 S thermal cycling reactions in a fume
33 P nucleotides
35 S nucleotides, and