Abstract
For the purpose of measuring aqueous solutions of biological compounds, especially nucleic acids and nucleotides, a very convenient Hyamine-water-toluene system was developed.
The composition of this counting mixture is:
10 ml of toluene scintillator (4 grams of PPO, and 0.1 grams of POPOP in 1 liter of toluene)
0.5 ml of 1M Hyamine 10-X chloride in ethanol up to 0.3 ml of aqueous sample solution when 1.0ml of Hyamine is added, the system can contain up to 0.4ml of aqueous solution.
Maximum efficiency for 3H is 18.3% and 14C is 53%. Efficiencies of aqueous solution of 3H- and 14C-UMP, uridine and uracil are compared with four different solvent systems, that is Hyamine-water-toluene, 70% toluene-30% ethanol-PPO-POPOP, dioxane-naphthalene-PPO-POPOP, and so-called“Bray solution”, at -8°C and 10°C. The best results are obtained for this Hyamine-water-toluene system described above.
1M Hyamine Cl in ethanol only has an effect as a solubilizing agent of aqueous solution with toluene scintillator. Commercial 1M Hyamine hydroxide in methanol, 1M Hyamine Cl in methanol, 1/2M in ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, or 2/3M in npropanol has no effect at -8°C. Higher alcohol than propanol can not dissolve Hyamine as 1M solution.
Quenching per cent for 0.1 ml of 1N HCl, 0.5N KOH, and 0.5M KCl are 2.5, 6, and 5%, respectively, in the case of 1 ml of 1M Hyamine Cl ethanolic solution is added. Even when 10 mg/0.2 ml of nucleic acid, UMP, uridine solution or 6 mg/0.1 ml of threonine solution is added, no precipitate or no quenching is observed.
