Robert R. Greenberg

Bioaccumulation of vanadium and other trace metals in livers of Alaskan cetaceans and pinnipeds.

Concentrations for 38 elements are routinely measured in the marine mammal liver tissues archived in the National Biomonitoring Specimen Bank (NBSB). Results show that hepatic concentrations of vanadium, selenium, silver, cadmium, and mercury are positively correlated with age for beluga whales (Delphinapterus leucas) and of vanadium, selenium, cadmium, and mercury with length for ringed seals (Phoca hispada). Many researchers have reported linear correlations of hepatic selenium, cadmium, and mercury with marine mammal age; however, there is only one other report of a linear correlation of hepatic vanadium with marine mammal age. Vanadium levels are at or below detection limits (⩽0.01 μg/g) in liver tissues of U.S. east coast marine mammals from the NBSB but are present at levels ranging from 0.02 to 1.2 μg/g of wet weight in the tissues of Alaskan marine mammals. Although only three bearded seal (Eriganthus barbatus) and three bow-head whale (Balaena mysticetus) liver samples have been analyzed, hepatic vanadium levels also increased with animal size for these species. The presence of relatively high levels of vanadium in the livers of these Alaskan animals may reflect a unique dietary source of vanadium, a unique geochemical source of vanadium, or anthropogenic input to the Alaskan marine environment.

Trace element concentrations in cetacean liver tissues archived in the National Marine Mammal Tissue Bank

The National Biomonitoring Specimen Bank (NBSB), a collaborative project of several U.S. government agencies, includes marine mammal tissues collected for the Alaska Marine Mammal Tissue Archival Project (AMMTAP) and the National Marine Mammal Tissue Bank (NMMTB). Tissues were collected from 139 animals representing 13 species of marine mammals from around the U.S. Recently, concentrations for up to 30 elements in liver tissues of nine long-finned pilot whales (Globicephala melas), six harbor porpoises (Phocoena phocoena), and four white-sided dolphins (Lagenorhynchus acutus) from the NMMTB were measured using instrumental neutron activation analysis. Results from analyses of these tissues are presented, compared with results for liver tissues from other marine mammals from the AMMTAP, and compared with published values.

Development of frozen whale blubber and liver reference materials for the measurement of organic and inorganic contaminants

SummaryFresh frozen homogenates of pilot whale blubber and liver tissue were prepared for use as control materials for the determination of organic and inorganic contaminants in marine mammal tissue analyses. The blubber material was analyzed to determine 30 polychlorinated biphenyl congeners and 16 chlorinated pesticides using gas chromatography with electron capture detection and gas chromatographymass spectrometry. A total of 39 trace elements and methylmercury were determined in the liver homogenate using instrumental neutron activation analysis, voltammetry, and cold vapor atomic absorption spectroscopy. The preparation and analysis of these two tissue materials are part of the development of marine mammal tissue reference materials.

Ultratrace determination of platinum in biological materials via neutron activation and radiochemical separation

A neutron activation analysis scheme based upon a radiochemical separation of the activation products has been developed. The method utilizes the inherent sensitivity of the activation reaction198Pt(n, γ)199Pt and counting of the daughter nuclide199Au. This nuclide is radiochemically separated from interfering activities by homogeneous precipitation as elemental gold. The remaining interference of the secondary reaction197Au(n,γ)198 Au(n,γ)199Au from gold in the samples is quantitatively assessed and corrected. During this process accurate gold concentrations in the samples are obtained at ultratrace levels. The analysis scheme is applied to gold and platinum determinations in biological Standard Reference Materials and human liver specimens. Gold and platinum are determined at concentrations of 5·10−11 g/g, and at higher levels.

Dissolution problems with botanical reference materials

SummaryAs part of the analytical research leading to the certification of the new Apple and Peach Leaves Standard Reference Materials (SRMs), a study was undertaken to evaluate different sample dissolution techniques for losses of analyte species. Possible loss mechanisms include absorption or adsorption of analyte elements at the walls of the sample decomposition vessels, and the formation or persistence of insoluble particulate material during sample dissolution. Results of this study indicated that significant fractions of some elements were present on particles after acid dissolution, despite visual indications that dissolution was complete. In addition, large amounts of some elements remained in the platinum crucibles used to fuse samples with lithium metaborate.

Neutron captue prompt gamma-ray activation analysis at the NIST Cold Neutron Research Facility

An instrument for neutron capture prompt gamma-ray activation analysis (PGAA) has been constructed as part of the Cold Neutron Research Facility at the 20 MW National Institute of Standards and Technology Research Reactor. The neutron fluence rate (thermal equivalent) is 1.5·108 n ·cm−2·s−1, with negligible fast neutrons and gamma-rays. With compact geometry and hydrogen-free construction, the sensitivity is sevenfold better than an existing thermal instrument. Hydrogen background is thirtyfold lower.

Metrology for Chemical Measurements and the Position of INAA

Metrology systems are being established by various countries for the worldwide comparability of data related to trade, industrial products, health, and the environment. This has in turn led to an increased interest in methods that have the highest possible accuracy and precision. The relevance of instrumental neutron activation analysis (INAA) for metrological science has been evaluated. It is concluded that INAA is a suitable technique for method validation, proficiency testing, development of reference materials and reference methods. Moreover, it is concluded that INAA may comply with the CCQM definition of a definitive or primary ratio method provided that the uncertainty in the results is reduced to much lower levels compared to those currently encountered in most NAA laboratories.

Measuring hydrogen by cold-neutron prompt-gamma activation analysis

By irradiating with cold neutrons and avoiding hydrogenous materials of construction, we have developed a PGAA instrument at the Cold Neutron Research Facility at NIST with hydrogen detection limits in the microgram range in many materials. Quantities of 5–10 μg H/g are presently measurable in gram-sized samples of silicon or quartz, and of order 0.01 wt % can be quantitatively measured in complex silicate rocks.

A RADIOCHEMICAL PROCEDURE FOR ULTRATRACE DETERMINATION OF CHROMIUM IN BIOLOGICAL MATERIALS

Chromium is one of the most difficult elements to accurately determine at the naturally occuring, ultratrace levels normally found in uncontaminated biological samples. In view of the importance of Cr, both as an essential and as a toxic element, efforts have focused on developing a simple, yet reliable, radiochemical procedure for Cr determination using neutron activation analysis. A number of problem areas have been identified in earlier methods, and an improved radiochemical separation procedure, based upon the liquid/liquid extraction of Cr(VI) into a solution of tribenzylamine/chloroform, has been developed. The fast neutron interference from Fe has been evaluated for the highly thermal RT-4 facility of the NBS Research Reactor, and Cr concentrations have been determined in samples of whole human blood collected under clean conditions and in two certified reference materials.

Simultaneous determination of twelve trace elements in estuarine and sea water using pre-irradiation chromatography

A procedure is described for the preconcentration of 100 ml of estuarine and seawater into a solid sample using Chelex-100 resin. This solid sample weighs less than half a gram and contains the transition metals and many other elements of interest, but is essentially free from the alkali metals, the alkaline earth metals, and the halogens. The concentrations of Co, Cr, Cu, Fe, Mn, Mo, Ni, Sc, Th, U, V and Zn have been determined in seawater when this procedure was coupled to neutron activation analysis.