Determination of metal-binding proteins in soft tissues of rock oyster by neutron activation analysis and particle induced X-ray emission

In this work, we determined the levels of trace metals in protein fractions isolated from rock oysters by neutron activation analysis (NAA) and particle induced X-ray emission (PIXE). Proteins were extracted from mantles and hepatopancreases of rock oysters and fractionated by size-exclusion high performance liquid chromatography (HPLC). The protein fractions from mantles and hepatopancreases are found to be abundant in Fe, Cu, Zn, Mn, Pb, and Ag. HPLC profiles of Fe, Cu, Zn, and Ag indicate that those elements are bound to proteins extracted from mantles and hepatopancreases.     

Rapid determination of silver in cultivated Japanese and South Korean oysters and Japanese rock oysters using the 24.6-s neutron activation product 110Ag and estimation of its average daily intake

Soft tissues of cultivated Japanese (Miyagi Prefecture) and South Korean (Koje-do and Kosong) oysters and Japanese rock oysters (Honshu Island) were analyzed to measure silver levels. The soft tissues, namely hepatopancreas, gill, muscle, and mantle were separated, freeze-dried, pulverized, and analyzed by an instrumental neutron activation analysis method in conjunction with compton suppression spectrometry (INAA-CSS). The method consisted of the irradiation of samples in a neutron flux of 5 × 10¹¹ cm^?2 s^?1 using the rapid transfer system in an inner pneumatic irradiation site of the Dalhousie University SLOWPOKE-2 reactor (DUSR) facility for 12–15 s, decay for 20 s, and counting for 60 s. The 657.8-keV gamma-ray of the 24.6-s nuclide ¹¹⁰Ag was used for assaying silver. The method was validated using NIST, NRC and NIES certified reference materials. An absolute detection limit of 0.05 μg silver using NIST SRM 1566b Oyster Tissue was achieved. About 10–50 times higher levels of silver were found in cultivated Japanese oysters compared to the South Korean ones. The silver concentrations in cultivated oysters in Miyagi Prefecture showed the following trend: gill > mantle > hepatopancreas > muscle as well as on the age. Rock oysters generally had higher silver content compared to cultivated oysters. A very preliminary value of about 0.466 μg silver average intake per person per day was estimated from the consumption of oysters by the people living in the Sendai city of Miyagi Prefecture.     

Study of the isomeric ratios in 107Ag(γ, n)106m,gAg reaction of natural silver induced by bremsstrahlungs with endpoint energies in the giant dipole resonance region

We measured for the first time the isomeric ratios in ¹⁰⁷Ag(γ, n)^106m,gAg reaction by using the activation method and γ-ray spectroscopic method for the whole giant dipole resonance region. The high-purity natural Ag foils in disc shape were irradiated with bremsstrahlungs generated from an electron accelerator Microtron. The induced gamma spectra in the irradiated foils were measured by the high resolution γ-ray spectroscopic system which consists of a high-purity germanium detector and a multichannel analyzer. In order to improve the accuracy of the experimental results, necessary corrections were made in the γ-ray activity measurements and data analysis. The results were analyzed, discussed and compared with those of other authors. For the above mentioned reaction, the isomeric ratios in the energy range from 14 to 24 MeV bremsstrahlungs in this work (except the values at 14, 18 and 20) are new measurements.     

Determination of gold by neutron activation analysis in some selected precambrian rocks from Eastern India

Gold was determined in some selected rock samples by neutron activation analysis. The analysis was carried out both in destructive and non-destructive ways followed by γ-ray spectrometry. The amounts of gold that were determined in the respective rock samples varied in the range 10⁻⁴–10⁻⁶%. Besides gold, some other trace constituents such as As, Ag, Sb, W, Se, La, Sm, etc. were also detected and their approximate order of occurrence was determined.     

Concentrations of108mAg,137Cs,and210Pb in oyster (Crassostrea gigas) on the Japanese coast in relation to the distribution and behavior of radionuclides in sea water

Concentrations of^108mAg,¹³⁷Cs, and²¹⁰Pb in oysters (Crassostrea gigas) were measured for about 10 years on the northeast coast of Japan. Silver-108m was detected in oyster samples collected from an open bay, and its concentrations decreased from the initial value of about 30 mBq/kg fresh in the early 1980s to the value of about 10 mBq/kg fresh in the early 1990s. This decrease could be mainly explained by effects of the ocean current in the early 1980s, and the coastal sea water thereafter, as well as by the advection and diffusion in the ocean. In the nearly-closed bays, concentrations of^108mAg and²¹⁰Pb in oysters were remarkably lower than in the open bays. It suggests that scavenging of silver and lead from the sea water effectively occurred in the nearly-closed bays. In contrast, concentrations of¹³⁷Cs in oysters were similar in the open bays and in the nearly-closed bays.     

Determination of trace impurities in palladium by neutron activation analysis

Trace amounts of Ir, Au, Ag, Pt, Zn, Mn, and Cu were determined in high purity palladium by destructive and instrumental neutron activation analysis (NAA). The latter version of NAA was employed for the determination of Ir, Au and Ag. Special attention was paid to a new non-destructive method for the determination of silver traces in palladium. The results obtained by both versions of NAA are critically discussed and compared.     

A novel arsenical in clam kidney identified by liquid chromatography/electrospray ionisation mass spectrometry.

Kidneys of clams of the genus Tridacna accumulate metabolic products from symbiotic unicellular algae that grow in the mantles of the clams. These metabolites include organoarsenic compounds that are biosynthesised by algae from arsenate in seawater. The arsenic compounds in aqueous extracts of the kidney of the giant clam T. derasa were investigated by liquid chromatography/electrospray ionisation mass spectrometry. About 50% of the water-soluble arsenic was present as dimethylarsinoylribosides and dimethylarsinate which are common algal metabolites. The major compound in the kidney (50% of water-soluble arsenic) was identified as a 5-dimethylarsinoyl-2,3,4-trihydroxycarboxylic acid, a new natural product.     

Determination of the major elements in homogeneous and heterogeneous samples by tandem laser-induced breakdown spectroscopy-partial least square regression

The tandem laser-induced breakdown spectroscopy-partial least square regression (LIBS-PLS) was applied for the analysis of both, a smelting product from a noble metal ore (as example of a homogeneous sample) and a calcareous rock from a Maya building (as a heterogeneous sample). The method was designed for the analysis of both samples without perceptible deterioration of the pieces, by monitoring the emission lines of the major elements present in each sample while subjecting the pieces to a number of laser shots. The results obtained, as well as the precision provided by the LIBS-PLS method, were statistically compared with those obtained by graphite furnace-atomic absorption spectroscopy (for Ag and Cu) and flame atomic emission spectroscopy (for Ca), showing good agreement between methods.     

Ag/TCNQ薄膜中的传质行为研究

采用真空蒸发的方法在玻璃基板上交替蒸发Ag和TCNQ(四氰基对醌二甲烷), 形成不同厚度的双层膜, 经Ag的固体化学扩散与TCNQ反应, 形成金属有机络合物. 利用透射光谱作为表征, 研究了Ag的传质规律, 给出了60~110 ℃温度下的恒温传质系数k和对应的激活能, 并对传质机制进行了探讨.     

Substoichiometric determination of trace impurities in zinc selenide

Determination of trace impurities in zinc selenide was carried out by substoichiometric neutron activation analysis. Trace impurities were separated from matrix elements by suitable procedures and determined by substoichiometric methods, i.e., Au was extracted with rhodamine-B, Ag and Cu with dithizone, Cr with sodium diethyldithiocarbamate, Co with 1-nitroso-2-naphthol, and Sb with cupferron. Two sorts of zinc selenide single crystals were supplied for analysis and the following values were obtained as impurity concentration; Au 0.36, 0.076 ppb, Ag 42, 32 ppb, Cr. 1.8, 0.63 ppm, Co 0.16, 0.0079 ppm, Sb 8.5, 5.9 ppb and Cu 1.4, 0.44 ppm. The behavior of copper by heat-treatment of zinc selenide was also studied by means of substoichiometric isotope dilution analysis.     

Trace-element analysis of argyle diamonds using instrumental neutron activation analysis

Thirty four elements were determined by instrumental neutron activation analysis in colourless, brown, and pink diamonds, with and without inclusions. These were compared with data obtained for similar elements in the host lamproite rock. The natural radioactivity of these samples was measured by instrumental techniques, and found to be negligible.     

Measurement of Ag, Te and Pd in geochemical reference materials by mass spectrometric isotope-dilution analysis

Procedures are described which permit mass spectrometric isotope-dilution analysis to be used to determine Ag, Te and Pd in rock samples at the ng g level. The concentrations (ng g ) of Ag, Te and Pd were found to be 25.7 +/- 0.7, 1.2 +/- 0.6 and 0.08 +/- 0.05 respectively in BCR-1 and 3.5 +/- 0.2, 4.2 +/- 0.7 and 2.9 +/- 1.7 respectively in PCC-1.     

Reliability of prompt gamma-ray analysis for the determination of Na and Mg in rock samples.

The reliability of neutron-induced prompt gamma-ray analysis (PGA) was examined for the determination of Na and Mg in geological and cosmochemical rock samples, because they tend to have been erroneously determined for such samples. JB-1 (basalt standard rock) and Allende (chondritic meteorite) powder samples were repeatedly analyzed by using thermal or cold neutron-guided beams of the JRR-3M research reactor at Japan Atomic Energy Agency. In critically evaluating calculated values for major prompt gamma-rays of Na and Mg, it was observed that a 472.2 keV peak for Na and a 2828.2 keV peak for Mg yielded reasonable consistency with corresponding recommended values. Sodium and Mg were determined for five lunar meteorites by PGA using these prompt gamma-rays, and were found to be consistent with their data obtained by instrumental neutron activation analysis.     

An Internal-Standard Method for Determination of Trace Impurities in Semiconductor Grade Silicon by Neutron Activation Analysis

An internal-standard method^1–4) has been applied for the determination of La, Sb, Au, Cr and Ag in silicon single-crystal by neutron activation analysis using cobalt as an internal-standard element. No chemical separation is required in this case and the precision obtained with the present method is satisfactory.     

Instrumental neutron activation analysis of a sulfide ore and some ore benefication products

Samples of a pyritic lead-zinc ore and some benefication products were examined by instrumental activation analysis using Ge(Li) gamma-spectrometry. The following elements were determined using thermal neutron activation: Sc, Cr, Co, Zn, As, Se, Ag, Sb, Ir, Au and Th. The technique is especially favourable for the determination of cobalt, arsenic, antimony and gold, but selenium, silver and thorium can also be determined in most fractions. Activation with epithermal neutrons will improve conditions for the determination of As, Sb, Se, Ag, Au and Th.     

Extractive separation of thorium(IV) as a sulphate complex with N-n-octylaniline

The distribution of Th(IV) between aqueous sulphuric acid and organic phases of N-n-octylaniline in xylene is described. The dependence of the metal extraction on acidity and extractant concentration is investigated. Based on the results obtained, the possible extraction mechanism is discussed. The determination of Th(IV) and its separation from synthetic mixtures is suggested. The method is extended to the analysis of thorium in monazite and gas mantles.     

Activation analysis of trace metals in several kinds of tissues of even-toed ungulates

The normal concentration levels of trace metals in several kinds of tissues of even-toed ungulates have been determined by instrumental neutron activation analysis, photon activation analysis, and flame atomic absorption spectrometry. In the present work the concentrations of 13 elements (Ag, Br, Ca, Co, Cu, Fe, Mg, Mn, Mo, Na, Rb, Se, and Zn) were analyzed.     

Determination of the silver content of ancient silver coins by neutron activation analysis

A reactor neutron activation analysis procedure for the determination of the silver content of silver coins is described. The samples are irradiated for 1 s, cooled for 85 s and measured for 60 s with a Ge-detector. The analysis is based on the measurement of¹¹⁰Ag and¹⁰⁸Ag. Aluminium is used for flux monitoring and pulse pile-up correction. A calibration curve is prepared by irradiating and measureing a series of discs with known silver contents. An average precision of ±2.1% is obtained. The analysis of coins with known silver contents shows good agreement with the given values. The analysis time is 2.5 minutes per sample.     

Comparison of solid phase extraction, saponification and gel permeation chromatography for the clean-up of microwave-assisted biological extracts in the analysis of polycyclic aromatic hydrocarbons

The feasibility of different clean-up procedures was studied for the determination of polycyclic aromatic hydrocarbons (PAHs) in biota samples such as oysters, mussels and fish liver. In this sense, once the samples were extracted--essentially with acetone and in a microwave system--and before they could be analysed by gas chromatography-mass spectrometry (GC-MS), three different approaches were studied for the clean-up step: solid phase extraction (SPE), microwave-assisted saponification (MAS) and gel permeation chromatography (GPC). The main aim of this work was to maximise the recoveries of PAHs and to minimise the presence of interfering compounds in the last extract. In the case of SPE, Florisil cartridges of 1, 2 and 5 g, and silica cartridges of 5 g were studied. In that case, and with oysters and mussels, microwave-assisted extraction and 5 g Florisil cartridges provided good results. In addition, the concentrations obtained for Standard Reference Material (SRM) NIST 2977 (mussel tissue) were in good agreement with the certified values. In the case of microwave-assisted saponification, the extracts were not as clean as those obtained with 5 g Florisil and this fact lead to overestimate the concentration of the heaviest PAHs. Finally, the cleanest extracts were obtained by GPC. The method was successfully applied to mussels, oysters and hake liver, and the results obtained for NIST 2977 (mussel tissue) were within the confidence interval of the certified reference material for most of the certified analytes.     

(Li/Ag)CoO2: a new intergrowth cobalt oxide composed of rock salt and delafossite layers

A new ordered (Li/Ag)CoO(2) layered compound with an unusual oxygen packing combining rock salt and delafossite layers is obtained during the (Li(+), Na(+))/Ag(+) ionic exchange from the OP4-(Li/Na)CoO(2) precursor. This compound is actually an intermediate step to the final D4-AgCoO(2) delafossite and can be isolated thanks to the kinetics difference between the Li(+)/Ag(+) and Na(+)/Ag(+) exchange processes. It crystallizes in the P6(3)/mmc space group with cell parameters a(hex.) = 2.848(3) ? and c(hex.) = 21.607(7) ?. The details of the structure as well as its thermal stability and transport properties are presented and discussed.