This paper presents the results of the application of a fast rabbit system and a high thermal neutron flux to neutron activation analysis of selenium in environmental samples. The short-lived radionuclide77mSe, (17.5s) is used for analysis. Results are presented for selenium in sea-water and rain-water, in biological reference materials, in food-stuffs and milk powder, in human hair and human blood-serum.
Radiotracer experiments have been used to study the retention of Na from 14M HNO3 mineralized serum samples by HAP in both batch and column processes. The specific capacity of HAP depends nonlinearly on
the ratio initial Na-amount/amount of HAP. Pre-irradiation removal of Na by HAP-columns and of Cl by evaporation permits Cu,
Mg an K in human serum to be determined by neutron activation analysis.
The determination of fluorine, calcium and phosphorus in bone by instrumental fast neutron activation analysis is described.
Results for the IAEA standard material “Animal Bone” A3-74 re: Ca=313±10 mg/g, P=155±5 mg/g and F-613±20μg/g. The accuracy
for all three elements is≤4%, precision being about 3%. The limit of determination for F is 120 μg, for Ca 30 mg and for P
1 mg in a sample of 500 mg.
An overview is presented of the characteristic features of RNAA (radiochemical neutron activation analysis). Criteria are given for comparison of RNAA with other trace-element analytical techniques. Appropriate fields of application of RNAA are indicated as well as approaches to secure the future position of the technique. Finally, some trends for further development of chemical separations in RNAA are outlined.
Two methods are presented for a fast, accurate and precise determination of210Pb in industrial samples with a calcium-phosphate and-sulphate matrix. One method combinessolid-liquid extraction on a Pb-selective column Sr*Spec (Eichrom) with gamma-ray spectrometry of210Pb and can be applied to samples >10 g for aselective210Pb determination. The yield is determined gravimetrically. The detection limit is 380 mBq for a 24 h counting period. The other method combineschromatography on Sr*Spec with liquid scintillation counting of210Pb for asensitive210Pb determination and can be applied to samples of up to 1 g. The yield is determined on-line by the UV signal of PbEDTA. The detection limit is 70 mBq for a 2 h counting period. Aspects of accuracy, precision, selectivity, sensitivity and the application of both methods to phosphogypsum and phosphate ores are presented.
A correction procedure is presented for the residual bias due to dead time losses in thermal INAA based on short-lived radionuclides. It is based on a linear least-squares fitting, starting from three pre-chosen (average) half-lives.
A method for the determination of trace amounts of Mo, Cd, Co and Cr in biological materials by neutron activation analysis with radiochemical separation is presented. The method is based on the ion-exchange scheme developed by SAMSAHL, where Co and Cr are trapped on BioRad Chelex-100 and Cd and Mo on BioRad AG2X8. The elements Mo, Cd and Co can be determined without systematic errors. For the element chromium the situation is less clear, partially due to lack of sufficient certified reference materials for Cr. The method has been used in the characterization of candidate reference materials. Detection limits in these materials range from 1.5 g/kg for Co to 10 g/kg for Cr. Actual levels as low as 8 g/kg for Cd and 7 g/kg for Co were measured.
Accuracy and precision of instrumental neutron activation analysis, based on short-lived radionuclides, are considered. Equations
are derived for both quantitives as a function of concentration and features of the γ-ray spectrum. The determination of vanadium
by way of52V(T=3.75 min) is used as an example.
Authors:J. Woittiez, S. Subramanian, K. Volkers and J. De Goeij
The idea to use high performance liquid chromatography with continuous UV detection for multi-element radiochemical separation and simultaneous multi-element on-line yield determination is introduced. The validity of the concept was evaluated by demonstrating the constancy of the ratio of the signals for a main isotope (60Co) and a carrier (59Co) as a function of the elemental mass processed in the separation. The suitability of the method for practical purposes is demonstrated by its application to the RNAA determination of cobalt in biological materials. It is concluded that the method, although not yet completely developed, bears the potential of improving both accuracy and precision of multi-element RNAA.
Authors:J. Luten, J. Woittiez, H. Das and C. De Ligny
The determination of iodate in rain-water by neutron activation analysis is described. Iodate is separated by anion exchange.
The determination limit of I is 0.02 μg·L−1 for a 20 ml sample. The influence of the sea on the composition of rain-water is demonstrated by the analysis of coastal
rain-water. The results indicate that inorganic iodine (I2 and IO
) is enriched in filtered coastal rain-water relative to the composition of sea-water.