Lead content trace elements

During wet digestion, certain components of the sample can be lost, leading to the underestimation of particular elemental contents. Trace elements can be lost by adsorption to the vessel walls, volatilization, coprecipitation, and coextraction. Although the exact nature of adsorption losses is unclear, it may... 

The technological information derived from a study of the early jettons can be summarized quite simply - before ca. AD 1450, European jettons contained on average around 4% tin and 1-2% lead, with a low zinc content, typically less than 10%. Traces of antimony, silver and arsenic are often present at 0.1- 02%. Nickel is very low, usually less than 0.05%. After AD 1450, the zinc content rises quickly to over 20%, with a corresponding fall in the lead (less than 1%) and tin (less than 0.2%). The trace elements are usually less than 0.1%, with the exception of nickel, present up to 0.5%. The combined copper plus zinc total is usually greater than 97%. 

Probably the most effective use of XRF and TXRF continues to be in the analysis of samples of biological origin. For instance, TXRF has been used without a significant amount of sample preparation to determine the metal cofactors in enzyme complexes [86]. The protein content in a number of enzymes has been deduced through a TXRF of the sulfur content of the component methionine and cysteine [87]. It was found that for enzymes with low molecular weights and minor amounts of buffer components that a reliable determination of sulfur was possible. In other works, TXRF was used to determine trace elements in serum and homogenized brain samples [88], selenium and other trace elements in serum and urine [89], lead in whole human blood [90], and the Zn/Cu ratio in serum as a means to aid cancer diagnosis [91]. 

The historic use of trace-element geochemistry around the McArthur River Uranium Deposit has primarily focussed on a limited suite of elements, including uranium, lead, nickel, copper, and boron. At McArthur River, uranium is distributed around the main deposit to significant distances (100 s of meters) in the overlying Athabasca Group (McGill et al. 1993), yet variations in the uranium content of this halo is typically restricted to 1-3 parts per million with little spatial variation, restricting one s ability to vector... 

Several options have been outlined for the reduction of mineral matter to low levels in filtered extract solution. These are mainly applicable to the British Coal process, but have implications for other 2-stage processes. By running the digestion at a pressure above about 30 bar and reducing the filtration temperature as required, low levels of trace elements have been obtained with a series of different coals and HAO solvents. Discarding the fine fraction of the coal from the feed to the digestor will also result in lower levels of trace elements in the extract solution, as will increasing the saturates content of the HAO. However, in the latter case this may also lead to reduced overall conversion. 

Mineral deficiencies are not uncommon and can have quite a variety of causes—e. g., an unbalanced diet, resorption disturbances, and diseases. Calcium deficiency can lead to rickets, osteoporosis, and other disturbances. Chloride deficiency is observed as a result of severe Cr losses due to vomiting. Due to the low content of iodine in food in many regions of central Europe, iodine deficiency is widespread there and can lead to goiter. Magnesium deficiency can be caused by digestive disorders or an unbalanced diet—e.g., in alcoholism. Trace element deficiencies often result in a disturbed blood picture—i. e., forms of anemia. 

The metal content can range from only a few parts per million to >1000 ppm. Trace elements such as iron, sodium, nickel, vanadium, lead, and arsenic can corrode metallic parts and damage heating equipment. Low levels of nickel, vanadium, and copper are known to deactivate refining catalysts. 

Preliminary studies have shown that it is possible to remove over half of the potentially toxic trace elements present in coal when the mineral matter is reduced by coal washing. When coal is burned in a power plant, about 13% of the mercury and about 50% of the lead and cadmium may remain with the fly ash. Analytical chemical techniques have been developed to determine Hg, Cu, Cr, Mn, Ni, Cd, Pb, and F in coal and fly ash. These techniques produce accurate and precise results despite the fact that there are no coals with established trace element content, except for mercury. 

Approximate contents of 14 minor and trace elements in oils produced from three coals by the catalytic hydrogenation process of Gulf Research and Development Co. were determined by emission spectroscopy. The results were compared with corresponding data for the original coals and the solid residues from the process. The contents of ash, sulfur, vanadium, lead, and copper are near or below the limits specified for an oil to be fired directly in a gas turbine while sodium and probably calcium are too high. Titanium appears to be somewhat enriched in the oils analyzed relative to other elements, suggesting its presence in organo-metallic complexes. 

Many analysts are faced with the problem of determining the content of trace and microtrace components in samples with complex and often varying matrix compositions. There is no doubt that this kind of analytical work poses a special challenge. The end result of analysis is influenced by a number of additional factors, which are not taken into account when the presence of higher content components is determined (these issues have been discussed in a great many publications).40 52 But the lack of awareness of these specific requirements when performing analytical research on various types of samples for trace elements may lead to situations where the obtained result, instead of being a reliable source of analytical data, will supply erroneous information. 

Aqueous washing of the fly ash provides a sorbent with the capacity to remove the elements in amounts in excess of that originally leached. The sorbent characteristic of fly ash is favored by combustion temperatures that lead to the fusion of the fly ash during its formation and the time it remains in the fused state. No correlation could be established between the sorbent characteristic of the fly ashes and their bulk major, minor, trace elemental compositions and the particle size of the fly ash particles. Only the carbon content of the fly ash could be related to its organic removal properties. 

Cahen, L., P. Eberhardt, J. Geiss, F. G. Houtermans, J. Jedwab, and P. Signer On a correlation between the common lead model age and the trace element content of galenas. Geochim. cosmochim. Acta 14, 134 (1958). 

The variations in trace elements in vegetables may be considerable (Warren 1972a) and may depend to a large extent on the nature of the soil in which the vegetables are grown. Table 5-12 illustrates the extent of the variability in the content of copper, zinc, lead, and molybdenum of a number of vege-... 

Some of the objects from Kastri falling in Trojan field B need further discussion. Four of these objects (16167, 16169, 16171, and 16174) have lead isotope compositions that resemble the fingerprint of Cypriot copper ores however, we have rejected the hypothesis that these metal objects at Kastri are Cypriot in origin by comparing their trace elemental composition, particularly gold and silver content, with some Cypriot copper artifacts excavated on Cyprus. The results of the neutron activation analyses of these objects are presented in Figure 11. 

Interactions Overabundance of one trace element can interfere with the metabolic use of another element available at normal levels. For example, addition of large amounts of zinc to a diet interferes with (antagonizes) intestinal copper absorption, resulting in copper deficiency from a diet with adequate copper content. Copper deficiency can provoke iron deficiency and anaemia. Molybdenum deficiency in animals can be induced by co-administration of large amounts of the similar element tungsten. Iron deficiency can also increase retention of cadmium and lead, and selenium has been proposed to protect against cadmium and mercury toxicity. 

Five of 19 Bassus quadrantes, BMC 265, contain > 0.300% iron. The concentrations of the remainder of the trace elements are quite normal in these 19 coins. The Capella coins, BMC 267, are quite ordinary with only one high iron content and one high lead content, 0.30% lead. The Blandus quadrantes, BMC 269, are also normal with only a few of the 24 coins having high iron or lead. No coin from these three series has relatively high tin (> 0.200% ) or high antimony (> 0.200% ). 

Using the Compton line of the tube as an internal standard reference sometimes enables a thorough correction of the matrix effects. This is illustrated by the analysis of trace elements Ni and V in petroleum products where the sulphur content is variable. Whilst, in the absence of sulphur, the matrix is extremely light and thus not particularly absorbent, an increase in sulphur content leads to a noticeable absorption of the Ni and V signals. The first curve in Figure 4.11 is plotted from net intensity levels measured on vanadium, whereas, in the lower curve the net V K. intensity levels have been replaced by the intensity ratios ... 

The problem of crustal contamination is particularly acute for low mg continental flood basalts and smaller volume continental tholeiitic basalts, both of which have low trace-element concentrations (see Sections 3.03.3.2.3 and 3.03.3.3). The issue is less critical for many smaller volume continental rocks, such as kimberlites and alkali basalts, which have much higher abundances of many trace elements. As a result of their high strontium and neodymium content, for example, the isotopic compositions of these elements in kimberlites and alkali basalts are relatively insensitive to modification during crustal contamination. Conversely, the osmium and lead concentration of basaltic magmas are so low that these isotope systems are particularly vulnerable to modification by interaction with cmstal rocks (McBride et al, 2001 Chesley et al, 2002) hence these systems provide relatively sensitive indicators of crustal assimilation. 

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