Body fluids, elemental analysis

The literature includes a number of mis-matches, the following standing as examples for the many The use of bovine liver and other animal tissues for QC in the analysis of hmnan body fluids should not be considered by analysts. The matrix and the levels of trace elements do not match the levels to be analyzed, which may lead to serious errors. An even more severe mis-use was recently reported by Schuhma-cher et al. (1996) for NIST SRM 1577a Bovine Liver, which was used for QC in the analysis of trace elements in plant materials and soil samples in the vicinity of a municipal waste incinerator. Also recently, Cheung and Wong (1997) described how the quality control for the analysis of trace elements in clams (shellfish) and sediments was performed with the same material NIST SRM 1646, Estuarine sediment. Whilst the selected SRM was appropriate for sediments, its usefulness as a QC tool for clams is difficult to prove see also Chapter 8. This inappropriate use is the more mystifying because a broad selection of suitable shellfish RMs from various producers is available. 

Flame emission spectrometry is used extensively for the determination of trace metals in solution and in particular the alkali and alkaline earth metals. The most notable applications are the determinations of Na, K, Ca and Mg in body fluids and other biological samples for clinical diagnosis. Simple filter instruments generally provide adequate resolution for this type of analysis. The same elements, together with B, Fe, Cu and Mn, are important constituents of soils and fertilizers and the technique is therefore also useful for the analysis of agricultural materials. Although many other trace metals can be determined in a variety of matrices, there has been a preference for the use of atomic absorption spectrometry because variations in flame temperature are much less critical and spectral interference is negligible. Detection limits for flame emission techniques are comparable to those for atomic absorption, i.e. from < 0.01 to 10 ppm (Table 8.6). Flame emission spectrometry complements atomic absorption spectrometry because it operates most effectively for elements which are easily ionized, whilst atomic absorption methods demand a minimum of ionization (Table 8.7). 

Atomic absorption spectrometry is one of the most widely used techniques for the determination of metals at trace levels in solution. Its popularity as compared with that of flame emission is due to its relative freedom from interferences by inter-element effects and its relative insensitivity to variations in flame temperature. Only for the routine determination of alkali and alkaline earth metals, is flame photometry usually preferred. Over sixty elements can be determined in almost any matrix by atomic absorption. Examples include heavy metals in body fluids, polluted waters, foodstuffs, soft drinks and beer, the analysis of metallurgical and geochemical samples and the determination of many metals in soils, crude oils, petroleum products and plastics. Detection limits generally lie in the range 100-0.1 ppb (Table 8.4) but these can be improved by chemical pre-concentration procedures involving solvent extraction or ion exchange. 

The investigation of body fluids with respect to nutrient (essential) elements and toxic elements -which are challenging topics for analytical chemistry - include the determination of concentrations at the trace and ultratrace level. However, isotope variation and isotope effects (especially of lighter elements such as hydrogen, carbon, nitrogen, oxygen but also of iron and calcium) have also been studied.22 23 The most frequently applied mass spectrometric technique for the analysis of body fluids today, which fulfils all requirements and also results in accurate and precise data, is ICP-MS. 

The literature on isotope dilution is so voluminous that it is impossible to cover the subject thoroughly in a single chapter. It is in fact tantamount to impossible to locate all relevant papers, let alone read them. There are also questions arising from the definition of inorganic. Elemental assay has traditionally been an inorganic discipline and analysis of, say, body fluids biological. The question is where, for example, to place analysis of lead in human serum. The area into which such analyses fall depends on whether it is the analyte or the sample that is used for the def-... 

Elemental analysis of body fluids and tissues by electrothermal atomisation and atomic absorption spectrometry... 

Elemental analysis of body tissues and fluids by atomic absorption spectrometry with electrothermal atomisation has advanced significantly the understanding of the role of trace elements in clinical biochemistry. All of those aspects of metabolic processes that are affected by changes in the concentrations of accessible trace elements have been studied. These include deficiencies of essential trace elements as a result of inherited or acquired metabolic disorders, or from nutritional inadequacy and excesses of trace elements producing toxicity states as a result of inherited metabolic disorders involving essential trace elements or from the inappropriate exposure to, or ingestion of, non-essential trace elements. 

PHYSIOLOGICAL CONCENTRATIONS OF ESSENTIAL TRACE ELEMENTS IN BODY FLUIDS AND SAMPLE VOLUMES REQUIRED FOR ANALYSIS BY ETA-AAS... 

Historically, the vitamins, like hormones, presented chemists with a considerable challenge. They are present in foods, tissues, and body fluids in very small amounts, of the order of /xmoles, nmoles, or even pmoles per kilogram, and cannot readily be extracted from the multiplicity of other compounds that might interfere in chemical analyses. Being organic, they are not susceptible to determination by elemental analysis as are the minerals. In addition, for several vitamins, there are multiple vitamers that may have the same biological activity on a molar basis (e.g., the vitamin Be vitamers. Section 9.1), or may have very different biological activity (e.g., the vitamin E vitamers. Section 4.1). 

All these different mechanisms of mass transport through a porous medium can be studied experimentally and theoretically through classical models (Darcy s law, Knudsen diffusion, molecular dynamics, Stefan-Maxwell equations, dusty-gas model etc.) which can be coupled or not with the interactions or even reactions between the solid structure and the fluid elements. Another method for the analysis of the species motion inside a porous structure can be based on the observation that the motion occurs as a result of two or more elementary evolutions that are randomly connected. This is the stochastic way for the analysis of species motion inside a porous body. Some examples that will be analysed here by the stochastic method are the result of the particularisations of the cases presented with the development of stochastic models in Sections 4.4 and 4.5. 

In considering the applications of AAS," the technique has made the biggest contribution to the determination of nonferrous metals and for the transition elements Cu and Ag, in particular, whose measmement is completely free from interferences due to Zn, Cd, Hg, Sn, Pb, Bi, or Sb. Blood sera and other body fluids are analyzed after deproteination using concentrated HCl, while for the analysis of plants, milk, and... 

The most commonly used is AAS (flame and non-flame), which allows both the identification and quantification of metals in solid, liquid, and gas samples [81]. ICP-AES allows analysis of impurities at trace levels (nanogram and picogram traces) [81]. ICP-MS allows both detection and analysis of most of the elements of the periodic table, as well as quantification of the concentrations of different isotopes of a given element in different matrices (body fluids, water, sewage, etc.). The limits of detection for many elements are at the 10 ° to 10 ppm [81]. 

The forces acting on the control volume consist of body forces that act throughout the entire body of the control volume (such as gravity, electric, and magnetic forces) and are proportional to the volume of the body, and surface forces that act on the control surface (such as ihe pressure forces due to hydrostatic pressure and shear stresses due to viscous effects) and are proportional to the surface area. The surface forces appear as the conlrol volume is isolated from it.s surroundings for analysis, and the effect of the detached body is replaced by a force at that location. Note that pres.surc represents the compressive force applied on the fluid element by the surrounding fluid, and i.s always directed to the surface. 

In clinical analysis, flame AAS is very useful for serum analysis. Ca and Mg can be determined directly in serum samples after a 1 50 dilution, even with microaliquots of 20-50 pL [314]. In the case of Ca, La3+ or Sr2+ are added so as to avoid phosphate interferences. Na and K are usually determined in the flame emission mode, which can be realized with almost any flame AAS instrument. The burner head is often turned to shorten the optical path so as to avoid self-reversal. For the direct determination of Fe, Zn and Cu, flame AAS can also be used but with a lower sample dilution. Determination of trace elements such as Al, Cr, Co, Mo and V with flame AAS often requires a pre-concentration stage, but in serum and other body fluids as well as in various other biological matrices some of these elements can be determined directly with furnace AAS. This also applies to toxic elements such as Ni, Cd and Pb, which often must be determined when screening for work place exposure. When aiming towards the direct determination of the latter elements in blood, urine or serum, matrix modification has found wide acceptance in working practices that are now legally accepted for work place surveillance, etc. This applies e.g. for the determination of Pb in whole blood [315] as well as for the determination of Ni in urine (see e.g. Ref. [316]). 

Everts I., Milton D. and Mason R. (1991) Trace element analysis in body fluids by glow discharge mass spectrometry a study of lead mobilization by the drug cis-platin, Biol Mass Spcctrom 20 153-159. 

In the past quarter of a century improvements in methods of total elemental analysis and the development of methods of measuring the different chemical forms in which an element may be present in a sample of tissue or body fluid have shown that metals may play pivotal roles both in health and in disease. Changes in the metal content of the human body may contribute to ill-health in various ways. Accidental or deliberate intake of much larger amounts of metals than those present in the normal diet may cause signs, or symptoms, of acute or chronic poisoning. 

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