Speciation analysis of trace elements is the identification and/or measurement of the quantities of one or more individual chemical species in a sample. The general procedure starts with the separation of the species followed by the measurement of trace elements in the different fractions. The identification of the species may be done by UV-detection, mass spectrometry or other techniques. For the development of the methodology, and for in-vivo and in-vitro studies radiotracers are ideally suited. In speciation analysis of trace elements in biological fluids and tissues the search goes on for small inorganic and organometallic compounds, and for metal-protein complexes.
The presence and the concentration of trace elements in hair are subject to variations according to a number of factors. The
primary investigations consist in a statistical interpretation of (1) the distribution of the oligo-elements in a homogeneous
hair sample, (2) the distribution over one particular head, (3) the evolution in samples taken at successive intervals, (4)
the distribution over a population. Our study was mainly concerned in the influence of the time factor, and revealed an unpredictable
behaviour of the elements under investigation (As, Sb, Au, Mn, Hg, Cu). There was only one exception: Zn. This unpredictable
behaviour of most of the oligo-elements is due to their being influenced by such external conditions as environment, washing,
hair dyes, diet and drug intake. The identification of hair samples on the basis of concentrations so inconstant and easily
influenced, is a most impromising endeavour. Furthermore the irregularity in distribution of the oligo-elements over the head
of one and the same person is not of a nature to make things easier. The existence of these factors not only wellnigh excludes
the possibility of an identification, but they furthermore make it difficult to confirm unequivocally that a hair specimen
belongs to a given person, to the exclusion of any other.
This paper brings forward some simple logistics to an improved sample handling of clinical specimens. This comprises clean room conditions, clean laboratory ware, ultra-pure reagents and good analytical practise. Sample handling procedures for blood, urine, soft tissues and pharmaceuticals will be briefly discussed.
Several modifications are proposed of the established methods of iodine determination in serum. Prior to the actual analysis,
the serum is lyophilized. This preliminary treatment permits the use of large samples. Through lyophilization human blood
serum samples can easily be reduced to one-tenth of the original weight. Reduction is even more dramatic with materials from
other than human origin. After irradiation the samples are subjected to chemical treatment in the presence of an iodine carrier
and131I-labelled thyoxine. This procedure has been adopted for the determination of the iodine content and the chemical yield in
one and the same radioactive measurement. The analysis technique itself consists of an open system Schöniger combustion. The
open combustion allows the use of large samples; the gases evolved are absorbed upon their subsequent passage through potassium
hydroxide and hydrochloric acid; the mineralization requires less than two minutes. After the addition of a substochiometric
amount of silver nitrate, silver iodide is precipitated from an ammoniacal solution as a flat sample, which has been found
ideally suited for high efficiency counting with a Ge(Li) detector. The spectrum gives evidence of an excellent decontamination
from the38Cl,80Br and82Br activities. The iodine content can be calculated from the ratio of the photopeak areas at 364.5 keV and 442.7 keV corresponding
to131I and128I, respectively. The chemical procedure requires a mere 15 min, and the recording of the γ-ray spectrum takes no longer than
30 min. The technique is not limited to serum only. It proved well suited for the analysis of many other types of biological
material, e.g. human skin tissues.
An analysis has been elaborated to determine the long-living γ-emitting fission products of uranium. It consists of a sodium
bisulphate melt of the fission product solution or the U-fuel, followed by liquid-liquid extractions. Afterwards the isotopes
are absolutely counted with a standardized 3″×3″ NaI crystal. The total γ-spectrum of the original fission product solution,
taken with a NaI crystal or a Ge−Li detector, is also analyzed mathematically by mixed γ-spectrometry. From a short post-irradiation
of the fission product solution the concentrations of both235U and238U are determined. The absolute amount of fission products related to the U-concentration allows the calculation of the percent
atomic burn-up, the irradiation time, the cooling period, the flux of the reactor and the original degree of enrichment of
Authors:Lin Xilei, D. Van Renterghem, F. De Corte, and R. Cornelis
A study is made of the correction, in k0-standardized NAA, for interferences caused by fast neutron induced threshold reactions, second order reactions and235U-fission. The following examples are elaborated: determination of the Cr and Sc concentrations in a reference human serum, corrected for the54Fe(n,)51Cr and44Ca(n,;
–; n,)46Sc interferences, respectively, and the determination of Zr, Cs, La, Ce, Nd and Sm concentrations in USGS BCR-1 and G-2, corrected for235U(n, f) interference. A detailed uncertainty analysis and a comparison of the analytical results thus obtained with other literature values proves that the interferences can be accurately corrected for by employing the usual neutron flux monitors in the k0-method, namely a Zr-foil and a dilute Au–Al alloyed wire.
Authors:R. Cornelis, J. Versieck, L. Mees, J. Hoste, and F. Barbier
Vanadium in serum has been investigated by the aid of neutron activation analysis (8 min irradiation at 8·1013 n·cm−2·s−1 in the reactor FR-II of the Kernforschungszentrum in Karlsruhe). The lyophilized samples were dry-ashed before irradiation
and the52V activity extracted after irradiation. The values for V in the sera of 22 healthy males ranged from 0.029–0.939 ng V·ml−1. There is a real assumption that some of the high figures are due to persons being contaminated with V. The 18 healthy females
yielded a mean value of 0.033±0.012 ng V·ml−1 for 17 of them and one additional value of 0.139 ng V·ml−1. These V-data are the lowest ever reported in the literature. The analyses of two packed blood cell samples yielded 0.031
and 0.020 ng·g−1, indicating that about 68% of the total V in blood is present in serum. There was no correlation between the V-content and
age, nor between the V-content and the cholesterol, triglycerides or the lipoprotein fractions in serum.
Authors:P. Lievens, J. Versieck, R. Cornelis, and J. Hoste
The eight segments of five normal human livers are analysed for 25 trace elements by radiochemical NAA. This consits of an
automated wet destruction of the samples and two distillations, followed by ion exchange procedures. Ru is used as triple-comparator
for the standardisation. Short-lived and matrix-isotopes are standardised by the Bowen's kale powder. The results reveal that
the coefficient of variation within the liver is smaller than 10% for the elements Cd, Cl, Cs, Cu, Fe, K, Mg, Mn, Rb, Se and
Zn. The highest range observed for the elements As, Br, Co, Cr, Hg, La, Mo, Na and Sb within a liver is smaller than the range
observed between the five livers.