Classical activation analysis of fluorine by thermal neutrons has a limited application because of frequent interference from
chlorine, the short half life20F (11.4 s) and too high dead time of detectors. A procedure is described for fluorine determination using19F (n,p)19O reaction. Use of a boron carbide shield has no effect on the activity of19O (boron ratio −1) but considerably reduces background and interference due to18O (n, γ)19O reaction. The technique has been successfully applied to the determination of fluorine in organic compounds even in the
presence of large amounts of chlorine and oxygen.
The activity concentrations of 234U and 238U in thermal groundwater, deep well water and river water samples from Central Poland were determined. Concentration of 234U and 238U in the examined waters varied from <0.013 (LLD) to 16.8 mBq/dm3 and from <0.013 (LLD) to 45.5 mBq/dm3 respectively. The highest uranium activity concentrations were measured in the thermal groundwater from Mszczonow and Cieplice,
while the lowest were observed in thermal ground water from Uniejow and Poddebice. In thermal groundwater from Skierniewice,
uranium activity concentrations were below lower limit of detection (0.013 mBq/dm3). The 234U/238U activity ratio varied from 0.37 (Cieplice) to 1.30 (Poddebice well water).
Using the technique of liquid scintillation,32P and45Ca activites were determined in biological samples such as bones, blood, milk and egg shells, white and yolk. Samples were
mineralized in 70% HClO4 and 30% H2O2 at 70 °C and measured after addition of the “Aquasol” scintillation liquid. A correction for quenching was made by the method
of sample channels ratio. High detection efficiencies were obtained, above 80% for45Ca and about 50% for32P in a second measuring channel. Recoveries amounted to 0.95–1.06 for32P and to 0.93–0.98 for45Ca.
The differential determination of203Hg and14C or35S in double labelled biological samples is presented. The biological samples were mineralized with 70% HClO4 and 30% H2O2 in minivals MILLI-6. The γ-activity of203Hg was measured on a well scintillation counter. The total activity, due to203Hg and14C or35S, was measured by the liquid scintillation technique after addition of Aquasol into the same vials. The method of external
standard channel ratio was used for standardization. Very good recoveries were obtained: 100±0.7% for203Hg and 94.6–101.0% for14C and35S. This method could be used for other β, γ and β-active nuclides with similar β-spectra.
Phosphorus-32 and chlorine-36 radioactivity was measured directly in commercially available tissue solubilizers using a liquid
scintillation counter. Various wavelength-shifting compounds: β-naphthol, 4-methylumbelliferone, 7-amino-1,3-naphtalenedisulfonic
acid, 2-hydroxy-3,6-naphthalenedisulfonic acid, anthranilic acid and salicylic acid were investigated to assess their suitability
for the improvement of counting efficiency. Salicylic acid was selected which is fairly stable in alkaline solutions of tissue
solubilizers and remarkably improves counting efficiency up to 90% for both nuclides. 0.1 g of soft tissues or blood can be
solubilized with 1 cm3 of tissue solubilizer containing 2 g/dm3 of salicylic acid directly in 6 cm3 scintillation minivials. The sample channels ratio method for colour quench correction was found to be satisfactory.
The activity concentrations of natural radionuclides in building materials applied in the State of Kuwait were measured in order to asses the radiological hazard from that source. The samples of raw materials: soil, sand, gypsum and cement as well as different kinds of concrete or bricks were analyzed by -ray spectrometry with a HPGe detector. The radium equivalent activity concentrations in the samples varied between 4.2 to 283 Bq kg–1. This value is generally significantly lower than the value of 370 Bq kg–1 which corresponds to an annual external radiation dose inside dwellings equal to 1.5 mSv. The hazard from external -radiation of building materials has been found to be comparable to that from external -fields of primordial radionuclides in the surface soil of Kuwait.
A method in which90Y the daughter product of90Sr decay is extracted by tributyl phosphate (TBP) from ashed powdered milk is described. The90Y which is in equilibrium with90Sr is back-extracted into the aqueous phase and coprecipitated with milligram amounts of ferric hydroxide. The proposed procedure makes it possible to obtain thin planar sources convenient for low level gas counters. The overall detection efficiency of 45.5% for90Y (including chemical recovery of yttrium) was achieved. The detection limit for 200 g powdered milk samples and 10 000 s counting time was 0.065 Bq·kg–1. The concentration of90Sr in three-year old samples (after Chernobyl accident) ranged from 0.81 to 1.31 Bq·kg–1.
A chemical procedure for transferring deposited solid matter from a cellulose filter into the liquid scintillation cocktail has been described. The influence of chemical and color quenching on alpha and beta detection efficiency, as well as on misclassification of beta and alpha pulses was corrected by an external standard method. Under the chosen pulse shape discrimination level (PSD), the alpha and beta detection efficiencies were above 85% and spillovers of alpha and beta pulses were below 10% and 2% respectively. Determination limits for samples containing up to 200 mg of mineral matter were 0.015 mBq m–3 for alpha, 0.055 mBq.m–3 for210Pb and 0.055 mBq.m–3 for beta activity (counting time 12000 s and volume of filtered air 1000 m3). The method has been applied for routine monitoring of210Pb as well as for gross alpha and beta activities of longer-living radionuclides (T1/2.>11 hrs) in suspended air matter.
A method in which222Rn is extracted from 0.5 1 water samples to 20 ml toluene is described. 10 ml toluene solution with extracted222Rn is directly added to a glass scintillation vial containing 10 ml of liquid naphthalene based scintillation cocktail. Apart from diluting by toluene, the final counting solution still has excellent properties in terms of: / separation by pulse shape analysis, detection efficiency and background in the -region. The detection limit of222Rn for 0.5 1 water samples was 1.5 mBq l–1 (for 12,000 s count time). The concentration of222Rn in different environmental samples such as rain, tap and mineral waters as well as deep well waters were determined.