Biomedical Engineering Reference
In-Depth Information
counting) in water, application of solid scintillators, autoradiogra-
phy on X-ray films without enhancers, or special equipment (Phos-
phoImager). Much more difficult is the counting of weak emitters,
such as, for example, tritium, since a lot of substances quench
radiation.
A lot of ready-to-use scintillation cocktails are available. Besides
counting efficiency, chemical, biologic, and environmental hazards
should be reflected when choosing a cocktail. Since vials and their
contents are radioactive waste, number and volume of vials should
be as small as possible.
To illustrate the composition of liquid scintillation cocktails
(LSC), some formulations follow.
A:
Bray solution: 6% naphthalene (w/v), 0.4% PPO (2,5-diphen-
yloxazole) (w/v), 0.02% POPOP (1,4-bis-2-(5-phenyloxazolyl)-
benzene) (w/v), 10% methanol (v/v), 2% ethyleneglycol (v/v)
in 1,4-dioxane
B:
15% naphthalene (w/v), 0, 8% PPO (w/v), 0.06% POPOP (w/v),
10% ethylglycol (ethyleneglycol monoethylether) (v/v), 2%
ethyleneglycol (v/v) in 1,4-dioxane
C:
6.5 g PPO, 0.15 g POPOP, 100 g naphthalene, 300 ml methanol,
500 ml 1,4-dioxane, 500 ml toluene
D:
“Tritosol” (handles up to 23% water (v/v) without decrease
in counting efficiency for tritium)
6
: 0.3% PPO (w/v), 0.02%
POPOP (w/v), 3.5% ethyleneglycol (v/v), 14% ethanol (v/v),
25% Triton X-100 (v/v) in xylene
6
Fricke U (1975) Anal Biochem 63:555
