Monostandard instrumental neutron activation analysis of Chinese Biological Standard Reference Material using short-lived radionuclides

A routine procedure for monostandard INAA using short-lived radionuclides with half-lives from 2 min to 15 hrs is described. Ten elements (Al, Mg, Ti, V, Mn, Cl, Na, K. Br and Cu) are determined in Chinese Biological Standard Reference Material (peach leaves). The quality of analysis was checked by analyzing the U. S. NBS Standard Reference Materials SRM-1571 and SRM-1648.     

Determination of Essential Elements in Ayurvedic Medicinal Leaves by k0 Standardized Instrumental Neutron Activation Analysis

Elemental concentrations of a few medicinal leaves are determined by instrumental neutron activation analysis using the single comparator (k ₀) method. Data obtained for neem leaves, collected from two different places, have been used to see the effect of soil condition. The applicability of the method particularly for the simultaneous determination of Ca, Mg, V and Al in biological matrices has been evaluated in terms of the detection limit, precision and accuracy. The method was validated by analysing the NIST Standard Reference Material (SRM-1571) and it was found that the elemental concentrations measured in SRM-1571 are within ±10% of the reported values.     

Mixed diet reference materials for nutrient analysis of foods: Preparation of SRM-1548 Total Diet

Summary Several mixed component diet materials have been available for use as reference materials for determination of elemental contents in food. These included H-9, issued by the IAEA and RM-8431, issued by NIST. Wide acceptance of these materials has exhausted supplies and they are no longer available. A new mixed food Standard Reference Material, SRM-1548 Total Diet, has been prepared and characterized for a number of elemental and organic constituents. This material was prepared from foods obtained from collections of the US FDA's Total Diet Study, which are representative of foods consumed by the US population. SRM-1548 has been composited from these foods, in proportions that are representative of daily intake. The composited foods were blended, freeze-dried, reblended and bottled in portions of 6 g. Homogeneity studies were carried out along with certification analyses for elements, cholesterol proximate and caloric content. This material is available from NIST and will be useful as a multi-purpose SRM for determinations of constituents in the naturally occurring range in foods and food related materials. Since this is a mixture of foods of both good and poorer sources, levels will be at the lower end of the concentration range for any individual constituent. Availability of further SRM's of individual foods with higher levels of specific constituents, such as SRM-1845 Cholesterol in Whole Egg will be required to extend the range of certified concentration values for food reference materials.     

Neutron activation analysis of 35 elements in Chinese standard rocks (GSR) and soils (GSS) using the SLOWPOKE reactor

Concentrations of 35 elements in Chinese Standard Rocks (GSR-1 to GSR-3) and Soils (GSS-1 to GSS-8) have been measured with INAA using the SLOWPOKE reactor. At the same time, the U. S. NBS reference standards: SRM-1632a (Bituminous Coal), SRM-1633a (Coal Fly Ash) and SRM-1646 (Estuarine Sediment) were also analyzed in order to cross-check the accuracy of this method. The results obtained indicate that the reproducibility of the method is satisfactory for most of the elements, namely the precision in general, is better than ±10%. Comparison of our values for NBS SRM-1632a, 1633a and 1646 with the certified values of NBS or with values cited in the literature indicates good agreement. The results were found to be accurate within ±10% error of the established results.     

Possibilities of the elemental analysis of dry biological material by fast neutron activation analysis

The applicability of a 400 kV neutron generator in the elemental analysis of dry biological material is considered. Data for the specific count-rates of 66 elements are given. A procedure for the determination of N, Mg, Si, P, K and Ca is described. The results for three Standard Reference Materials and some samples are given.     

Instrumental neutron activation analysis of trace elements in quartz

A scheme for INAA of 32 elements (As, Au, Ba, Br, Ca, Cd, Ce, Co, Cr, Cs, Eu, Fe, Hf, Hg, Ir, K, La, Lu, Mn, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, W. Yb, Zn) in quartz glass is proposed. The accuracy of the procedure is evaluated by the analysis of two NBS standard reference materials (SRM-1571 and SRM-1632-a). The method is convenient for routine work. The method was used for the determination of impurities in laboratory quartz glass. Dedicated to the 60th birthday of acad. prof. g. bliznakov     

Characterization and traceability of two generations of standard reference material for the measurement of vitamin K1(phylloquinone) at endogenous concentrations in human plasma and serum

Vitamin K is an essential micronutrient required for blood coagulation, regulation of vascular calcification and bone mineralization. Plasma and serum measurements of vitamin K₁(phylloquinone, K₁) made using high-performance liquid chromatography with fluorescence detection, or tandem mass spectrometry are used clinically and in population studies to assess vitamin K status. Standard reference materials provide a validation tool for laboratories, helping assure clinical diagnosis and the comparability of data from different populations. We manufactured two K₁ standard reference materials, in 2009 (KEQAS SRM-001) and in 2019 (KEQAS SRM-002). The target concentrations of K₁ were assigned to each SRM using the All Laboratory Trimmed Mean of results reported by selected laboratories enrolled in the Vitamin K External Quality Assurance Scheme (KEQAS). The assigned concentrations of K₁ for KEQAS SRM-001 and SRM-002 were 0.25 and 0.36 μg/L respectively. In 2019 KEQAS SRM-001 was re-analysed simultaneously with KEQAS SRM-002 to provide traceability between the two standards, therefore aiding comparability of analysis performed using these materials. Both standards were stored as aliquots at −80°C in the dark; annual re-analysis of the materials indicated that K₁ is stable for at least 12 years in these conditions.     

Possibilities of low-level determination of silicon in biological materials by activation analysis

The capabilities of neutron and photon activation analysis (NAA and PAA, respectively) for low-level determination of silicon in biological materials have been examined. Sensitivities of a variety of modes of NAA and PAA with radiochemical separation have been evaluated. Results are presented for silicon in reference materials CSRM 12-2-03 Lucerne, Bowen's Kale, NIST SRM-1571 Orchard Leaves, and NIST SRM-1515 Apple Leaves. The results were obtained by employing the 29Si(n,p)29Al reaction with fast reactor neutrons and the radiochemical procedure developed for aluminium separation. Possibilities of further improvement of the silicon determination limit down to the microg g(-1) level by employing NAA and PAA with radiochemical separation are outlined.     

Possibilities of low-level determination of silicon in biological materials by activation analysis

The capabilities of neutron and photon activation analysis (NAA and PAA, respectively) for low-level determination of silicon in biological materials have been examined. Sensitivities of a variety of modes of NAA and PAA with radiochemical separation have been evaluated. Results are presented for silicon in reference materials CSRM 12–2-03 Lucerne, Bowen’s Kale, NIST SRM-1571 Orchard Leaves, and NIST SRM-1515 Apple Leaves. The results were obtained by employing the ²⁹Si(n,p)²⁹Al reaction with fast reactor neutrons and the radiochemical procedure developed for aluminium separation. Possibilities of further improvement of the silicon determination limit down to the μg g^–1 level by employing NAA and PAA with radiochemical separation are outlined.     

Direct determination of normal physiological concentrations of major,minor and trace elements in undiluted microlitre volumes of human body fluids by discrete nebulization and atomic emission spectrometry with a nitrous oxide/acetylene flame

The concentrations of major (Na, K, Ca, Mg), minor (Cu, Fe) and trace (Li, Sr, Ba) elements in untreated, undiluted human body fluids (serum, urine, saliva, cerebrospinal fiuid) are determined. The sample volume is 110 μl. Micro-standard addition procedures and manual background correction are used to minimize matrix interferences. The RSD ranged from 3.1. to 8.6%. Accuracy was evaluated with NIES Candidate Reference Material freeze-dried human serum and NBS SRM-2670 freeze-dried urine.     

Optimization of an urban particulate matter multi-element analysis method by inductively coupled plasma--atomic emission spectrometry (ICP-AES)

In the present work a method for simultaneous metals determination, in urban air particulate matter by ICP-AES has been set up. A large number of elements (18) has been analyzed, including major (Al, Fe, K, and Mg), minor (Na, Pb and Zn) and trace (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Sb, Sr and V) elements. The procedure consists of microwave sample acidic total digestion by HNO3/HF mixture and subsequent analysis by ICP-AES, using different assemblies depending on sample treatment procedure: a quartz Meinhard nebulizer/cyclonic chamber, if HF excess was eliminated, or a cross-flow nebulizer/plastic Scott chamber, suitable for application with HF. A cyclonic chamber for hydride generation was used for As, Sb and Hg determination. The procedure was tested with Standard Reference Materials 1648 NIST Urban Particulate Matter and Certified Reference Material No8 NIES "Vehicle Exhaust Particulates". Two sampling supports, quartz fibre and polycarbonate filters, have been examined in order to find the most suitable i.e. the one characterized by less interference. Some real samples of urban air particulate matter, TSP, PM10 and PM2.5 fractions, collected during an intercomparison campaign promoted by Regione Lombardia, have been analyzed with the procedure developed.     

Determination of multielement in optical waveguide and standard reference materials by instrumental neutron activation analysis

Trace amounts of transition elements (Co, Cr, Cu, Fe, Mn and V) and other seven elements in optical waveguide samples were determined by INAA. The contents of impurities in ultra-pure materials are less than those of high-purity materials and of G.R. grade. The increase of contamination of trace transition elements and iridium from furnace or crucible are observed in the production of optical glass fibers. Up to seventeen elements were determined in five NBS biological standard reference materials: Oyster Tissue: SRM-1566, Brewers Yeast: SRM-1569, Spinach: SRM-1570, Orchard Leaves: SRM-1571 and Tuna Fish, and in four Japanese biological standard reference materials: Tea Leaves B&C, Pepperbush and Shark Meat. The analytical results in NBS and Japanese standard reference materials are in good agreement with published values and certified values by NBS.     

Exploiting in situ hydride trapping in tungsten coil atomizer for Se and As determination in biological and water samples

A flow injection hydride manifold was coupled to a 150 W tungsten coil electrothermal atomizer for in situ hydride collection followed by selenium and arsenic determination by ET AAS. Rhodium (200 μg), thermally reduced over the double layer tungsten atomizer, was very efficient at collecting selenium or arsenic hydrides. Prior to analysis, biological samples were digested in closed-vessels microwave digestion system. Prior to the hydride formation, both selenium and arsenic were reduced to valence state (IV) and (III), respectively. The detection limit was 35 ng L⁻¹ for selenium and 110 ng L⁻¹ for arsenic. Sample throughput was 70 h⁻¹ using 30 s of hydride trapping time. Method accuracy was evaluated by analyzing biological-certified reference materials from the National Institute of Standard and Technology (SRM-1577a and SRM-1577b “bovine liver” and RM-8414 “bovine muscle powder”) and from the International Agency for Energy Atomic (A-13 “animal blood”) and one water-certified reference material from the National Institute of Standard and Technology (SRM-1640 trace elements in natural water). By applying a t-test, there was no significant difference at the 95% probability level between the results obtained with the proposed method and those certified values.     

Neutron activation analysis of dry biological materials using mineralization with a saturated Mg(NO3)2-solution and scavenging by activated carbon

The combination of wet open mineralization with a saturated Mg(NO₃)₂-solution and the scavening of trace elements by active carbon are discussed. Experiments with spiked aliquuots serve to establish the chemical yeilds. The procedure is then checked by the analysis of Standard (Reference) Materials from the NBS and the IAEA. The elements Sc, Fe, Co, Zn, Cu, Se, Sb, W, Hg, Au and some lanthanides can be obtained with no apparent systematic bias and at a reasonable precision.     

Simultaneous determination of sixteen major and minor elements in river sediments by energy-dispersive x-ray fluorescence spectrometry after fusion in lithium tetraborate glass

Fluvial sediments, including the NBS SRM-1645 Standard River Sediment, were fused in lithium tetraborate to form glass discs on which determinations of 16 elements (K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr and Pb) were obtained simultaneously at a single set of x-ray conditions by energy-dispersive x-ray fluorescence spectrometry (e.d.x.r.f.). Relatively high sample-to-flux ratios of 1:3 were employed to obtained determinations of several minor as well as major elements on a single disc. Lower sample concentrations 1:6 and 1:10 were also used with the NBS SRM-1645. Inter-element corrections for absorption by iron were significant for detectable elements heavier than iron. In the NBS SRM-1645 samples, corrections were made for the fluorescence of chromium by the Fe K lines as well as the absorption of the Fe K lines by chromium. A background correction was also necessary for manganese in NBS SRM-1645. At the lowest sample-to-flux ratio (1:10) good agreement was obtained between the e.d.x.r.f. determinations and the NBS values for all quantifiable elements except zinc. At higher sample-to-flux ratios, agreement with the NBS values was generally poorer with increasing sample concentration. The relative standard deviation (RSD) of the eight quantifiable major and minor elements (K, Ca, Ti, Mn, Fe, Zn, Sr and Zr) determined under a single set of x-ray conditions ranged from 2 to 9% (RSD) with a mean RSD of 4.4% for a set of replica discs fused with Lake Pueblo/Arkansas River sediment samples.     

Use of INAA in the preparation of a set of soil reference materials with certified values of total element contents

A set of certified Reference Materials was prepared consisting of four natural agricultural soils with normal (n) and elevated (e) levels of element contents: CRM 7001 Light Sandy Soil (n), CRM 7002 Light Sandy Soil (e), CRM 7003 Silty Clay Loam (n), and CRM 7004 Loam (e). In these materials, certified and/or information values of the total contents of the elements As, Ba, Be, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, V and Zn, and their fractions extractable by aqua regia, boiling and cold 2M nitric acid were derived from an interlaboratory comparison in which 28 laboratories participated. Highly precise and accurate procedures of instrumental neutron activation analysis (INAA) were employed for homogeneity testing and also for certification of the total element contents. For comparation purposes, NIST SRM-2704 Buffalo River Sediment was analyzed by INAA, as well. The INAA results obtained compared very well with the certified and/or information values for four soil CRMs and also with NIST values for SRM-2704. From this agreement, a very high reliability of the new soil CRMs can be inferred.     

Analysis of biological reference materials, prepared by microwave dissolution, using inductively coupled plasma mass spectrometry

A procedure has been developed for the analysis of biological materials by inductively coupled plasma mass spectrometry (ICP-MS). Fast, efficient and complete sample digestion is achieved by a combined microwave-nitric acid/open beaker-nitric acid-hydrogen peroxide procedure. The ICP-MS analysis is performed with an on-line five-element internal standard to correct for matrix and instrumental drift effects. Results are presented for 24 elements in three biological reference materials (National Institute of Standards and Technology Standard Reference Materials 5277a Liver and 1566 Oyster and International Atomic Energy Agency Certified Reference Material H4 Animal Muscle). For all elements significantly above the detection limit and reagent blank concentrations, good agreement exists between ICP-MS and certified values.     

Data quality of PAH determinations in environmental monitoring

The sources of uncertainty affecting measurements of pollutants include sample collection, handling and stocking, and analytical procedure. With regard to chemical analysis, MS detection offers a series of advantages for resolving complex mixtures and identify and quantify analytes present at very small extents. Nevertheless, it presents some problems of reproducibility, which can affect the quality of quantitative data. PAH represent key-compounds among atmospheric pollutants and are usually evaluated by means of dedicated methods comprising MS detection. Based upon the above considerations, an analytical method has been standardized, suitable for determining PAH in atmospheric aerosols and diesel particulate exhausts. To test the procedure, both diesel particulate and urban aerosol NIST reference materials (SRM-2975 and SRM-1649A, respectively) have been processed and the results have been compared with certified and/or literature data. The results obtained are shortly discussed.     

A different approach to hair analysis: Application to multiple sclerosis

The results connected with the preparations of uranium and plutonium Standard Reference Materials, in which the content of the main compound is certified are considered.     

Homogeneity test of Chinese Biological Standard Reference Material by means of instrumental neutron activation analysis

A homogeneity test of 14 elements (Al, Cl, Mn, K, Ca, Ce, Th, Hf, Cs, Sc, Fe, Zn, Co and Eu) was made in Chinese Biological Standard Reference Material (peach leaves) by means of INAA. The procedures are described and the results are presented and discussed.