Search Results

You are looking at 31 - 40 of 886 items for :

  • "trace elements" x
  • Chemistry and Chemical Engineering x
  • Refine by Access: All Content x
Clear All

Determination of trace elements in petroleum by neutron activation analysis

I. Determination of Na, S, Cl, K, Ca, V, Mn, Cu, Ga and Br

Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Shah, R. Filby, and W. Haller

Abstract  

Using thermal neutron activation and a large-volume high-resolution Ge(Li) γ-ray spectrometer, the feasibility of the determination of the concentrations of Na, S, Cl, K, Ca, V, Mn, Cu, Ga, and Br in crude oils has been demonstrated. This instrumental method, which requires neither a chemical separation technique nor pre-concentration or post-concentration of trace elements by ashing, eliminates many inherent errors associated with chemical determination. The method is sensitive, precise and suitable for routine analysis. Fast neutron (n, p) and (n, α) reactions do not appreciably interfere and where necessary corrections may be applied. Loss of volatile elements, e.g. chlorine and bromine, due to recoil during irradiation is negligible.

Restricted access

Abstract  

Concentrations of up to 16 elements have been determined in subcellular fractions of bovine kidney using INAA methods. Levels of Rb and Se have been measured by a cyclic INAA method. A conventional INAA method consisting of 2 irradiations and 3 counting periods has been employed to determine the other elements. Accuracy of measurements has been evaluated by analyzing several standard reference materials. Trace element content of reagents used has been investigated in detail. Fresh samples of bovine kidney have been homogenized in a buffer containing sucrose and HEPES, and the homogeneate separated into nuclei, mitochondrial, lysosomal, microsomal and cytosol fractions by successive differential centrifugation. Concentrations of trace elements have been measured in these fractions using the INAA methods.

Restricted access

Abstract  

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.

Restricted access

Abstract  

Instant soups are a new group of dried foods and will play an important role in the nutrition of people because they fulfill present and future social consumer requirements. Instrumental neutron activation analysis has been applied in this work to determine the trace elements cesium, cobalt, iron, rubidiu, scandium, strontiu, silver and zinc in instant and long-time soups from the Greek market. According to our results, instant soups have the same iron content as those reported in the literature for bovine muscle, rice, legumes, porcine muscle and some meat products. Instant soup zinc content is the same as those reported for avian muscle, onions, rice, potatoes and sausages. Moreover the consumption of one planteful of instant soup offers to the human body about 8% of the daily required iron and about 2% of the daily required zinc.

Restricted access

Abstract  

Lake Nasser, one of the largest man made lakes in the world, is the reservoir created by the High Dam in the southermost part of Egypt and extends beyond Daal Cataract in the Sudan. The reservoir is about 480 kms long, of which, 300 kms are in Egypt (Lake Nasser) and 180 kms in the Sudan (Lake Nubia) and extends approximately within the latitudes of 21 No in the Sudan and 24 No in Egypt. In the west is the Great Western Desert and in the east the Eastern Desert of Egypt which extends up to the Red Sea. The deepest part is found near the High Dam (Lake Nasser) which reaches approximately about 86 metres. The depth decreases to the south and reaches approximately about 15 meters at Akasha in the Sudan. The Lake is much more wider in the egyptian part. The attached map shows the geographical locations of the lake from which the samples were collected. This work deals with the determination of 38 trace elements in water by neutron activation analysis (NAA). Also some parameters such as pH, (electric conductance), CO2−, HCO 3 , CO2, SO 4 2− , residue (after evaporation), dissolved oxygen, NO 2 and temperature were determined in the field. The temperature ranged from 20.7–29.7°C, while the pH values from 7.45 to 9 (for the bottom and surface waters). The dissolved oxygen was determined and found to be 0.8–9.4 mg/l for bottom and surface waters, respectively.

Restricted access

Abstract  

The fruit bodies of wild-growing higher fungi (macromycetes), commonly called mushrooms, of various genera and species collected in localities with different geochemical features and man-made burden in the Czech Republic were analyzed by different modes of activation analysis. The elements Na, Mg, Al, S, Cl, K, Ti, V, Mn, Cu, Br, Ba and Dy were determined by short-term instrumental neutron activation analysis (INAA). Short-term epithermal INAA (ENAA) was used for determination of I and other elements, such as Rb, Ag, and U. The elements Na, K, Sc, Cr, Fe, Co, Cu, Zn, As, Se, Br, Rb, Ag, Cd, Sb, Cs, Ba, La, Ce, Sm, Eu, Hf, Au, Hg and Th were determined by long-term INAA, whereas long-term ENAA enabled determination of several other elements, such as Ni, Ta, W and U. The analytical possibilities of instrumental photon activation analysis (IPAA) using a microtron were also explored and found useful for determination of several additional elements, namely Sr, Y, Zr, Nb, and Pb. High concentrations of several essential and toxic trace elements found (up to hundreds of mg.g-1, dry mass) should be of concern in nutritional studies, because mushrooms form non-negligible part of diet in many countries, especially in Middle and East Europe.

Restricted access

Abstract  

The potteries found on the Tremiti Isles (Italy, Adriatic Sea) have been characterized through their trace elements content. The goal of the work was to find out the number of ore deposits that supplied the clay used to manufacture the pottery. Neutron activation analysis has been employed for trace elements content determinations; the results have been statistically evaluated, clusterized and discussed.

Restricted access

Abstract  

Activated charcoals were analyzed by neutron activation analysis to test their applicability as sorbents for some volatile trace elements in volcanic exhalations. A high temperature volatilization process was applied, which reduces the concentrations of some trace elements, in particular Br, Hg, Sb and Zn.

Restricted access

Abstract  

Three watersheds were studied by sampling bulk precipitation deposition, seepage water at 50 cm soil depth and spring water. As the main analytical method for determination of trace elements and heavy metals in water samples, thek 0-based method of INAA was used. The results showed an increased content and concentration range of trace elements in precipitation, soil water and spring water in the vicinity of the otanj Thermal Power Plant. We demonstrated that thek 0-based method of INAA as a multielement nondestructive technique is a highly suitable approach to determining some toxic trace elements in environmental studies of the water cycle.

Restricted access

Abstract  

The suitability of zone electrophoresis and of free-liquid electrophoresis for investigation of the physico-chemical forms of trace elements in aqueous solutions has been examined. Comparison of the electrophoretic mobilities of tervalent cerium determined by these two methods has demonstrated that adsorption of trace elements on the supporting medium renders zone electrophoresis unsuitable for investigation of hydrolytic and other reversible reactions of trace elements accompanied or preceded by significant adsorption. Free-liquid electrophoresis should be preferably used for this purpose as it is much less complicated by adsorption effects.

Restricted access