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  • Author or Editor: N. Siddique x
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Abstract  

The IAEA conducted the IAEA-CU-2006-06 Proficiency Test (PT) on “The determination of major, minor and trace elements in ancient Chinese ceramic” in 2006. The results of this PT showed that of the 21 analytes reported by our laboratory 9 failed the precision criteria. Therefore the results reported by our laboratory along with the results of other laboratories which carried out analysis using neutron activation analysis (NAA) were studied. It was found that the major factor contributing towards data falling in the “Warning” category, failing the precision criteria was the high uncertainties cited in the certificates of the reference materials (RMs) used for quantification of data. In this regard, it is recommended that synthetic standards should be prepared and used on a routine basis especially for the measurement of the elements K, Eu, Lu, Ta, Tb and Yb.

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Abstract  

The International Atomic Energy Agency Marine Environmental Laboratory (IAEA-MEL) conducted an intercomparison exercise for the “Trace elements and methyl mercury in fish scallop: IAEA-452” in 2009. The Neutron Activation Analysis (NAA) laboratory at PINSTECH, Pakistan took part in this exercise. Comparison with the IAEA results showed that of the 18 elements reported to the IAEA 7 had unacceptable z-scores while the data for two elements was questionable (2< |z-score| <3). Upon investigation it was discovered that the large number of elements having unacceptable z-scores was due to human error and the greater difficulty in analyzing biological samples which have low amounts of trace elements. Therefore selection of values corresponding to matrix matched reference materials (RMs), such as IAEA-436 and IAEA-407, and to non-interfering peaks the results obtained became comparable to the IAEA results with only the result for As having |z-score|> 3.

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Abstract  

A study was undertaken to assess the air quality of Lahore by the elemental analysis of air conditioner (AC) filter dust samples collected from 15 different commercial sites. Samples were prepared using the Leeds Public Analyst Method and were analyzed using instrumental neutron activation analysis (INAA) for up to 31 elements. The elements Al, As, Ba, Ce, Co, Cr, Cs, Fe, Hf, K, La, Lu, Mn, Na, Nd, Rb, Sc, Sm, Sn, Ta, Th, Yb and Zn were detected in all 15 samples whereas the remaining elements have been detected in fewer samples; i.e. Mg, Sb and Tb were detected in 14 samples, Br and V in ten samples, U in nine samples and Ca and Ti in eight samples only. Al, Ca, Fe, K, Mg and Na were determined in all samples at percentage levels. The concentrations of most elements were found to lie around the mean values for the 15 samples studied and were not orders of magnitude different. However the concentrations of Ca, Mg, Sn and Zn were found to be more variable and were found to be dependant on activities such as construction, fruit and vegetable handling, tin plating and transport, respectively.

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Abstract  

A proficiency test (PT) exercise was offered by the International Atomic Energy Agency (IAEA) for major, minor and trace elements in Chinese ceramic reference material (IAEA-CU-2006-06). Neutron activation analysis (NAA) laboratory at PINSTECH, Pakistan participated in the exercise and submitted the results for 28 elements. The aim of participation was to develop a suitable methodology for accurate measurement of as many elements as possible in ceramic material using a low power reactor (PARR-2) as this would help future investigation in a project on the authenticity of art objects, for provenance, conservation and management of ancient cultural heritage of the country. After receiving the final report of the PT exercise, a critical review of our data and final scoring of each element is made to check the suitability of our methodology and reliability of the acquired data. Most of the reported results passed different statistical evaluation criterion such as relative bias, z-score and u-scores and ratio of our results and IAEA target values. One element (Yb) falls in the unacceptable range of relative bias and z-scores. Hf and Tb showed slightly high z-scores within the questionable range. Ho, Mo and Sn were determined during this study but their results were not submitted to the IAEA. The confidence of accuracy observed for most of the elements in ceramic material has made it mandatory to report their results as information values.

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Abstract  

The elements Cd, Cr, Cu, Mn, Ni, Pb and Zn were determined in dust samples collected from air conditioner (AC) filters from 15 commercial sites of Lahore using flame atomic absorption spectroscopy (FAAS). The elements Cr, Mn and Zn were also determined using instrumental neutron activation analysis (INAA). The results obtained showed that higher amounts of these metals were measured in these dust samples than normally found in soil. This was especially true for Cd, Cu, Pb and Zn. Generally the amounts of Cd, Cr and Mn did not vary throughout the city of Lahore but the amounts of the traffic related Cu, Pb and Zn elements had the more variable ranges of 30–140, 30–230 and 74–2810 mg/kg respectively. The concentrations obtained for Cr, Mn and Zn by INAA were found to be higher than those obtained using FAAS. Analysis of the data obtained showed the digestion procedure employed to be the possible cause for this occurrence. It was also found that Mn was being over-estimated by INAA due to the interference from the Mg peak.

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Abstract  

Instrumental Neutron Activation Analysis (INAA) and Atomic Absorption Spectroscopy methodology was developed to characterize the hazardous and other inorganic trace element constituents in new and used domestic plastic food containers. INAA due to its non destructive, highly sensitive, multielement and low detection limits characteristics was found to be a good technique for the characterization of polymeric products. Through the variation of irradiation, cooling and counting protocols Al, Ba, Br, Co, Cr, Eu, Fe, Hg, K, Mn, Na, Nd, Sb, Sc, Th, Ti, V and Zn were determined, while Atomic Absorption Spectroscopy was used as complementary technique to quantify toxic inorganic elements such as Cd, Pb and Cu. These elements are thought to originate from the polymer manufacturing processes. It was found that there was gradual increase in the concentration of most of these elements from new to used plastic samples. Moreover it was also observed that these inorganic elements are present in higher concentrations in the lower grade containers as compared to the high quality containers. It was also observed that the good quality containers even with the long usage do not degrade to such an extent as the low quality containers.

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Summary  

A national intercomparison exercise was conducted to remove inconsistencies and improve analytical procedures in the measurement of hafnium and zirconium in zirconium ores. The ZH-A series of reference samples, prepared at the Pakistan Institute of Nuclear Science and Technology (PINSTECH), were used for this purpose. It was observed that measurement errors decreased with increasing Hf concentration (~298-17500 ppm) for most techniques, especially for AAS due to the sample preparation procedure required for this technique. Of all the tested techniques most reliable results were obtained with neutron activation analysis (NAA) for the measurement of Hf and Zr in such matrices.

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Abstract  

INAA and AAS techniques have been employed to determine 40 elements in soil of a municipal waste dump in sector H-11, Islamabad. Background soil was also analyzed to study the extent of contamination of the dump site soil. Most of the major elements in these soils represented the geochemical composition of the soil in this area. The enrichment factors for quantified elements identified high Sb and Mg contents that could be attributed to the presence of PET and food materials in the waste. Geo-accumulation Index (I geo), Pollution Index (PI) and the Integrated Pollution Index (IPI) have also been calculated for all elements. The values for these indices show that municipal waste has distorted the soil ambiance and the soil of waste dump site is slightly to moderately polluted as compared to the background soil. The dump soil was found to be moderately polluted by the elements Ba, Br, Ga, Rb, Zn, Ni and Pb. Significantly high Cu, Mg and Sb contamination was observed for the waste soil that is likely to pose an environmental issue if current waste disposal procedures are continuously employed.

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