J. Holzbecher

The rapid determination of total bromine and iodine in biological fluids by neutron activation

Total bromine and iodine are instrumentally determined in 1 mL samples of body fluids by neutron activation under a boron shield at normal concentration levels. No sample treatment is necessary. Bromine is determined by its 80Br nuclide (617.0 keV; T1/2 = 18.0 min) and iodine by its 128I nuclide (442.7 keV;T1/2 = 25.0 min). The method is rapid; four bromine and two iodine determinations can be done in one hour. Bromine and iodine can be detected down to 14 micrograms/dL (1.75 mumol/L) and 2.9 micrograms/dL (0.23 mumol/L), respectively.

Determination of uranium by thermal and epithermal neutron activation in natural waters and in human urine

Abstract Uranium is determined via its 239 U nuclide (74.0 keV, t 1 2 = 23.5 min) in natural waters down to 0.03 ng U ml -1 after preconcentration with activated carbon and oxine; 30-min irradiation and counting times are used. No preconcentration is required for samples containing more than 4 ng U ml -1 with 10-min irradiation and counting times. Uranium in urine can be determined under a boron shield at the 5 ng ml -1 level after 30-min irradiation and counting.

Elemental Anomalies at the Cretaceous-Tertiary Boundary, Woodside Creek, New Zealand

Iridium and 26 other elements were determined in shale from the Cretaceous-Tertiary boundary at the locus classicus (for iridium anomalies) at Woodside Creek, New Zealand. Iridium, gold, copper, cobalt, chromium, nickel, arsenic, molybdenum, and iron were enriched in the basal 2 millimeters of the 8-millimeter shale parting as compared with the rest of the stratigraphic column. No other shale partings in the column had anomalous concentrations of any element when the data were expressed on a carbonate-free basis. The boundary material showed striking compositional similarities with the Stevns Klint Danish boundary shale. Elemental concentrations were in general much higher in the New Zealand material than in nonboundary shales from elsewhere in the world. The high concentration of iridium (153 nanograms per gram) in the basal layer of the boundary, together with the enrichment of other siderophile elements supports the idea of an extraterrestrial source for much of the material. The iridium/gold ratio of 2.1 is also in accordance with such a source. The iridium content of the basal layer is higher than for any other marine boundary shale obtained on land. The integrated iridium value is 187 nanograms per square centimeter of boundary surface.

Analytical applications of peroxyoxalate chemiluminescence

Abstract Peroxyoxalate chemiluminescence can be applied to the determination of hydrogen peroxide and aromatic hydrocarbon fluorophores in a static system. Hydrogen peroxide causes a linear response in the range 10 -6 –10 -1 M when bis(2,4,6-trichlorophenyl) oxalate is used with perylene as the fluorophore. As the intensity of chemiluminescence from different aromatic hydrocarbons varies substantially, there is a degree of selectivity in their determination. If metal chelates are employed as fluorophores, trace metal analysis is possible.

Extractable organohalogens in tissues of beluga whales from the Canadian Arctic and the St. Lawrence estuary

Samples of blubber, brain, kidney, liver, and muscle of individual beluga whales were extracted and analyzed for extractable organic Cl (EOCl), Br (EOBr), and I (EOI) by neutron activation analysis. The highest levels of EOCl (554 microg g(-1) lipid) were found in the kidney of Arctic beluga and the lowest (24 microg g(-1) lipid) in the blubber. Levels in brain and liver lipids were on average of equal magnitude. The unequal distribution of EOCl in tissue lipids is in marked contrast to the equal distribution, in lipid, demonstrated for organochlorines such as DDTs and PCBs by a number of investigations. The distribution of brominated (EOBr) and iodinated (EOI) compounds was similar and markedly different from that of EOCl. The tissue distribution of EOCl seems to be related to the proportion to polar lipids in the tissues. Beluga from St. Lawrence had significantly higher brain EOCl levels than the Arctic samples whereas the levels of EOCl in liver and kidney were higher in the Arctic whales.

Rhodium and osmium in iron meteorites

Abstract Rh and Os were quantified by instrumental neutron activation analysis in 106 iron meteorites. The data for Rh are the first extensive values to be reported for this element in iron meteorites. The Rh vs. Ni concentration plot allows for good spatial separation of groups IB, IC, IIA, IIB, IIC, IID, high-Ni IIICD, IVA and IVB. Low-Ni IIICD meteorites (Nandan and Cranbourne) seem to belong spatially to Group IA to which they were originally assigned. Os concentrations are strongly correlated with those of Ir. A plot of Os vs. Ni gives poorer group separations than that of Rh vs. Ni. Only in the cases of groups IB, IID, high-Ni IIICD and IVB are there convincing spatial separations. Once again, the low-Ni Nandan and Cranbourne fall within the IA field. Other data lend additional support to a previous proposal that Lamesa and Dayton be paired because of their similar chemical composition.

An evaluation of some substituted hydrazones as analytical reagents

Abstract Substitution of a more extended π-system on the aldehyde moiety of nitrogen-containing heterocyclic hydrazones considerably increases the spectrophotometric sensitivity of chelation reactions. The reaction rate, extractability into non-polar solvents and stability of extracts to light decreases as the size of the ligand molecule increases. The ligands react with a limited number of metal ions and the excellent extractability of the chelates formed and their high molecular extinction coefficients make them attractive reagents for trace metal separations and determinations: except for palladium, the absorption spectra of the chelates are similar. The palladium(II) chelate absorption above 600 nm is 100 nm removed from the other metal bands and, since other platinum group metals do not react, these compounds are highly selective and sensitive reagents for palladium. Phenanthridine-2-aldehyde-2-pyridylhydrazone permits accurate determination of a fraction of a p.p.m. of zinc in a 1.00-cm cell but cadmium interferes.

Stratigraphic occurrences of iridium anomalies at four Cretaceous/Tertiary boundary sites in New Zealand

Three new iridium anomaly sites have been discovered in Cretaceous/Tertiary boundary sequences in New Zealand. These are at Needles Point, Chancet Rocks, and Waipara, where integrated iridium deposition values were 165, 211, and 7 ng/cm2, respectively. In contrast to the previously reported Woodside Creek stratigraphic sequence that had an iridium anomaly of 187 ng/cm2, a ferruginous boundary clay is absent in the three new sites, though the base of the Tertiary is marked by limonite staining. The relatively weak anomaly at the Waipara section is probably due to extensive bioturbation coupled with a high sedimentation rate at the time of deposition. The discovery of these additional boundary rock sequences in New Zealand negates suggestions that the Woodside Creek iridium anomaly was a fortuitous occurrence caused by unusual weathering conditions. The integrated iridium deposition values at these three new sites of somewhat different geology support the previously reported high iridium level for Woodside Creek, which until now was the only iridium anomaly on land in the Southern Hemisphere.

The fluorimetric determination of mercury

Abstract Mercury (II) in solutions less than 0.02 M in foreign salts is selectively and simply determined at the 10–500 ng ml -1 level by measuring the fluorescence produced on reaction with thiamine. Sample sizes to provide 10 μg or more of mercury must be taken for samples which require acid digestion before analysis ( e.g. organics), because of the need for dilution to avoid salt interference.

Analysis for trace elements with a slowpoke reactor

Abstract The SLOWPOKE reactor is very useful for neutron activation analysis and has been in operation at Dalhousie University for ten years. Improvements to the reactor are out-lined and flux evaluations after major changes are reported. Its use for the determination of trace elements in a broad variety of materials is described.