Bio-Rad Personal Molecular Imager™ (PMI™) System - Manual (Page 21)

17
Fig. 4.5. Protective sheet placement steps.
Wet Radioactive Samples
Precautions must be taken to prevent wet samples from contaminating the imaging screen.
Wet thin samples should be completely enclosed in a heat-sealable bag, and moist samples
must be covered with plastic wrap before being exposed to the imaging screen.
Caution: Direct contact of a wet sample with the imaging screen may cause irreversible
screen damage.
Caution: Alkaline denaturing gels must be neutralized before being wrapped and exposed
to the screen.
Caution: Never expose the K/Tritium screens to wet samples, even if they are covered.
Plastic wraps will attenuate weak beta radiation signals according to the following table.
Table 4.2 Attenuation of Radiation by Various Plastic Wraps
Note: When enclosing a sample in plastic wrap or a heat-sealable bag, make sure that
there are no large air bubbles or surface wrinkles on the side of the sample that will come
into contact with the screen. Air bubbles and wrinkles will prevent close contact with the
screen, which may result in poor image quality and reduced sensitivity.
Note: Ensure that the external surface of the wrap or heat-seal bag is wiped dry to minimize
potential screen contamination.
Wrap Type 32 P 14 C 3 H Application
2 mm Seal -a-Meal bag 16% 82% >99.9% Wet samples
0.5 mm Saran wrap 6% 50% 99.7% Moist samples
!