Nigerian coal analysis by PIXE and RBS techniques

PIXE and RBS techniques were employed for the measurement of the concentrations of the major, minor and trace elements in Nigerian coal samples from a major deposit. The samples were irradiated with 2.55 MeV protons from the 3 MeV tandem accelerator (NEC 3 UDH) in Lund. The PIXE results are reported and compared with an earlier work on Nigerian coal using FNAA and INAA analytical techniques while the RBS results are compared with ASTM previous results. The results show that Nigerian coals have a low (0.82–0.99)% sulfur content. This is quite important for pollution control reasons.     

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.     

INAA multielemental analysis of Nigerian bituminous coal and coal ash

Instrumental neutron activation analysis (INAA) was used to analyzed Nigerian bituminous coal and ash. Good statistical agreement (p0.05) between the literature and reported elemental values of USGS AGV-1 sample was found. Many elements were determined in the coal with some enrichment in the coal ash. Arsenic was measured only in the ash while Hg was present only in the coal. Coal ashing at 800°C contributed to a loss of Hg in the ash. Al, Na, Mg, Ti, Fe, which are major elements were found in the coal as expected, with slight enrichment in the ash. Ca and Si were only obtained in the ash. High ash Al (14.9±0.19%) and Si (25.3±4.11%) levels are of concem due to possible cases of pneumononiosis from inhalation of the particulates. Graphical illustration of the lanthanide concentrations peaked at Ce with a decrease from Sm to Lu. U and Th were also present in the samples showing slight enhancement in the ash. Comparatively low coal elemental values, notably S(1.8%), highly advocate this coal as a good quality fuel-coal.     

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.     

Multielement analysis of Nigerian traditional (black) soaps

The element contents of some Nigerian traditional soap samples have been determined using thermal neutron activation analysis technique. The quality control consists of replicate analyses of standard 1632A bituminous coal for precision and accuracy determination. Potassium is found to be the major element in the soaps. While some elements show fairly constant concentration in all the samples analyzed, others have high maximum/minimum ratios. The elemental concentration variation in the soaps may likely have effects on their relative foaming capability and such variation is linked to the physical environment where the startingmaterials are obtained.To whom correspondence should be addressed at the Department of Chemistry, University of Ife, Ife-Ife, Nigeria.     

Determination of constituent elements in some Nigerian medicinal plants by thermal-neutron activation analysis

This study of the inorganic chemical composition of 10 different Nigerian medicinal plant species, using the technique of instrumental neutron activation analysis /INAA/, resulted in the determination of the concentrations of 18 major, minor, and trace elements: Al, Ba, Br, Ca, Cl, Eu, Fe, Ga, K, La, Mn, Na, Sb, Sc, Si, Sm, V, and Zn. The parts of the plants used were roots, leaves, and bark. The NBS SRM 1571 Orchard Leaves was also analyzed to assess the accuracy of the procedures used.     

Application of the k0 standardization method in reactor nuetron activation analysis of standard steels and fly ash

The method of k₀ standardization is suitable for routine multi-element determinations by reactor neutron activation. Investigation of NBS steel standards showed the systematic error of the method to be less than 3%. Numerical evaluation of the spectra was found to be fast and convenient. Fourteen elements in the steel samples were determined; for nine, the standard deviation was less than 4%. Thirty seven elements were determined in NBS SRM-1663a Coal Fly Ash; agreement with certified values was again very good.     

Assessment of ICP-MS for routine multielement analysis of soil samples in environmental trace element studies

Summary The suitability of inductively coupled plasma mass spectrometry (ICP-MS) following acid digestion of samples was evaluated for the routine determination of trace elements in contaminated and control soil samples. The contaminated samples were collected near an expressway and two secondary lead smelters in Toronto. All samples were acid digested in pressure vessels using a combination of reagents including hydrofluoric and perchloric acids. Consequently, the total amount of the elements (Pb, Sb, Cd, As, Mn, Mo and Cr) were being determined. In the case of lead direct comparison and isotope dilutional MS procedures were compared. Standard Reference Materials (SRM's) were run to allow an assessment of precision and accuracy. Isotope ratios were determined in the contaminated samples to evaluate whether this approach could be used, routinely, to determine the source of the lead. National Bureau of standards (NBS) 981 isotope ratio reference sample was used to evaluate the accuracy of the lead isotopic ratio data.Generally, the results obtained for the total amounts of the elements in the SRM's were in satisfactory agreement with the certified values. The measured isotopic ratios had a small positive bias compared to the NBS certified values. Isotope dilution MS values for Pb were superior in accuracy and precision to those obtained by direct comparison calibration. At the present state-of-the-art, routine isotope ratio measurements are not good enough for source typing in a study such as this. Values obtained in the present investigation compared well with those reported in a 1974 study of same areas.     

Characterization of coal fly-ash particles by laser microprobe mass spectrometry

Laser microprobe mass spectrometry (LMMS) was applied to coal fly-ash particles prefractionated to homogeneous composition with respect to particle size and density. For major elements, semiquantitative results (<50% relative standard deviation) were obtained; and the characteristic density dependence found for Si, K, Ca and Fe was in good agreement with that obtained by scanning electron microscopy/energy-dispersive x-ray analysis (EDX). The relative sensitivity coefficients, based on concentrations evaluated from the EDX data, coincided with those obtained for the NBS glass particle standard in previous work.     

Homogeneity tests and certification analyses of coal fly ash reference materials by instrumental neutron activation analysis

The instrumental neutron activation analysis technique (INAA) was used for homogeneity tests and certification analyses of coal fly ash reference materials ENO, ECH, and EOP prepared at the Institute of Radioecology and Nuclear Techniques (IRANT), Koice, Czechoslovakia. Quantitative estimation of a degree of inhomogeneity was suggested. The relative standard deviations due to inhomogeneity were found to be <1% for macroconstituents and <3% for minor and trace elements for sample weights about 25 mg. The results of determination of the elements Al, As, Ba, Ca, Ce, Co, Cr, Cs, Dy, Eu, Fe, Ga, Hf, In, K, La, Mn, Na, Nd, Ni, Rb, Sb, Sc, Sm, Sr, Ta, Th, Ti, U, V, W, and Zn were compared with the IRANT certified or information values. NBS SRM 1633a Trace Elements in Coal Fly Ash was also analyzed as a control sample and the results for the above elements were compared with the NBS certified, information or literature available values. From these comparisons, inference was made on the quality of the IRANT specified values for the element contents.     

INAA of toxic elements in coal and their transfer into environments

An instrumental neutron activation analytical (INAA) technique is described for the determination of 26 toxic and other trace elements in Eastern Coal (NBS SRM-1632a), local coal and its ash. The coal ash was produced by heating coal at 750°C in a muffled furnace. The transfer of these elements to the environment on the complete compustion of coal is estimated from the difference between the elemental concentration of coal and its ash.     

Determination of oxygen, nitrogen, and silicon in Nigerian fossil fuels by 14 MeV neutron activation analysis

Classification, assessment, and utilization of coal and crude oil extracts are enhanced by analysis of their oxygen content. Values of oxygen obtained "by difference" from chemical analysis have proved inaccurate. The oxygen, nitrogen, and silicon content of Nigerian coal samples, crude oils, bitumen extracts, and tar sand samples were measured directly using instrumental fast neutron activation analysis (FNAA). The total oxygen in the coal ranges from 5.20% to 23.3%, in the oil and extracts from 0.14% to 1.08%, and in the tar sands from 38% to 47%. The nitrogen content in the coal ranges from 0.54% to 1.35%, in the crude oil and bitumen extracts from ; 0.014% to 0.490%, and in the tar sands from 0.082% to 0.611%. The silicon content in the coal ranges from 1.50% to 8.86%; in the oil and the bitumen extracts it is <1%, and in the tar sands between 25.1% and 37.5%. The results show that Nigerian coals are mostly sub-bituminous. However, one of the samples showed bituminous properties as evidenced by the dry ash-free (daf) percent of carbon obtained. This same sample indicated a higher ash content resulting in a comparatively high percentage of silicon. In oils and tar sands from various locations, a comparison of elements is made.     

Elemental analysis of local soda samples using instrumental neutron activation analysis

Nigerian soda samples have been analyzed for major, minor and trace elements using instrumental neutron activation analysis. The following elements were determined; Na, Sm, U, La, Cr, Eu, Zn, Hf, Fe, Sc, Ba, Rb, Cs, Co, Au, Yb, Lu, Th, Ce, Zr, Se, As and Ta. The samples appear safe to use in human diet, although they may still require industrial purification to bring down the level of nonessential elements and those that could be toxic when present at high concentration.     

Determination of trace elements in reference materials by the k(0)-standardization method (INAA)

Instrumental neutron activation analysis was applied to four reference materials: NBS 1573 (Tomato Leaves), NBS 1645 (Citrus Leaves), NBS 1645 (River Sediment), and IAEA MA-A-2 (TM) (Fish Flesh). The k(0)-standardization method was used. The results are compared with (i) reference values (mostly non-certified) and (ii) published values obtained by other methods. Good agreement is found for most of the elements. For some elements, large discrepancies are observed.     

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.     

Neutron activation analysis of geological and biological samples using short-term reactor irradiation and successive counting

Short-term reactor irradiation followed by successive counting over long periods has been used for the nondestructive determination of more the 20 elements in geological and biological samples. The samples, along with USGS standards and NBS SRMs, were irradiated for 5 m, 10 m, 15 m, 1 h, 2.5 h, and 10 h, followed by counting on a Ge/Li/ gamma-ray spectrometer. The technique has been employed for the determination of several major, minor, and trace constituents in geological, biological and environmental samples.     

Trace elements in Nigerian oil sands and extracted bitumens

The Nigerian oil sands are very extensive with an estimated in place reserves of bitumen/heavy oil of over 30 billion barrels. Instrumental Neutron Activation Analysis (INAA) has been used to determine the trace and minor elements in the raw oil sands and bitumens. About 43 trace elements in the raw oil sands and 30 in bitumen extracts were determined. The results are compared with values of Canadian bitumens and some Nigerian conventional light crude oils. In general, the Nigerian bitumens has higher hydrocarbon concentration than the Athabasca bitumen but slightly lower than in the Nigerian crude oils. The sulphur, vanadium and nickel contents of the Nigerian bitumens and crude oils are appreciably lower than those of Athabasca bitumen, thus indicating that the extraction and refining of Nigerian tar sand oil would pose less technological and environmental problems than the Athabasca syncrude.     

电感耦合等离子体原子发射光谱法同时测定植物样品中多种元素

本文为环境样品分析建立了准确、灵敏、快速的分析方法,探讨了酸类及酸度对谱线强度的影响,同时对基体元素的谱线干扰进行了校正和背景扣除,测定了环境背景值样品树干和树叶中15种元素,经标样测定结果满意。     

Simultaneous multielement analysis of various human tissues by inductively-coupled plasma atomic-emission spectrometry

Human soft tissues were analysed by inductively-coupled plasma atomic-emission spectrometry (ICP-AES) for twelve elements. The tissues had been vacuum-dried for storage and were dry-ashed at low temperature and then digested with nitric acid prior to analysis. Accuracy and precision were examined by analysing NBS Standard Reference Material 1577 Bovine Liver. For P, K, Na, Mg, Ca, Fe, Cu, Zn and Cd, the concentrations obtained were within 4% of the certified or informational values. It was found that cerebrum, cerebellum, heart, kidney, liver, pancreas, spleen and muscle samples in portions of less than 1 g dry weight could be conveniently analysed for these elements.     

Trace determination of iron,cobalt, nickel and copper in zirconium fluoride by substoichiometric radioactivation analysis

Trace amounts of transition elements (Fe, Co, Ni and Cu) in zirconium fluoride and NBS SRM's were determined by substoichiometric radioactivation analysis. The contents of impurities in sublimed sample were less than those of high-purity material and of reagent grade. The detection limits of these elements in zirconium fluoride were 10 ng/g for iron, 0.01 ng/g for cobalt, 1 ng/g for nickel and 0.1 ng/g for copper. The analytical results for iron, cobalt, nickel and copper in NBS SRM's were in good agreement with certified values.