Total element analysis

In characterizing layered silicate, including layered titanate (HTO), the surface charge density is particularly important because it determines the interlayer structure of the intercalants as well as the cation exchange capacity (CEC). Lagaly proposed a method of calculation consisting of total elemental analysis and the dimensions of the unit cell [15] ... 

In soil analysis, the sample pretreatment varies depending on whether a total elemental analysis or an exchangeable cation analysis is required. In the former, a silicate analysis method (see below) is appropriate. In the latter, the soil is shaken with an extractant solution, e.g. 1 M ammonium acetate, ammonium chloride or disodium EDTA. After filtration, the extractant solution is analysed. Fertilizers and crops can be treated as chemical and food samples, respectively. 

Extraction of soils for analysis of die readily available nutrients include replacement of exchangeable cations by salt solutions, dilute acids, and dilute alkalies such as NaHCCh. Fluoride solutions ate employed to repress iron, aluminum, and calcium activity during the extraction of phosphorus. Extraction of the soil solution is effected by displacement in a soil column, often through the application of pressure across a pressure membrane. The soil solution is analyzed by conductance and elemental analysis methods. Also, the total elemental analysis of soils is made by Na2CC>3 fusion of the soil followed by classical geochemical analysis methods. 

This section is not intended to give a comprehensive account of environmental sampling problems, but rather to emphasize the importance of giving the necessary thought to sampling technique. Because many environmental samples are biologically active even when handed into the analytical laboratory, they must be stored and handled accordingly, especially if speciation studies are to be performed rather than total element analysis. 

METHODS FOR TOTAL ELEMENTAL ANALYSIS IN WHOLE MILK... 

Atomic spectrometry techniques are the most widely used for the total elemental analysis in milk samples. The choice of FAAS, ET-AAS, or ICP-AES depends on the concentration of the element sought, the required accuracy and precision, the number of elements to be determined, and so on. 

TABLE 13.7. Most Relevant Applications of Atomic Techniques for the Total Elemental Analysis of Milk Samples... 

If a water sample contains both soluble and insoluble manganese (Mn) compounds and ions, and it is filtered to separate the dissolved and insoluble fractions, and the filtrate and insoluble residue are analyzed separately, the results can be expressed as total dissolved Mn and total suspended or insoluble Mn. Phosphorus (P) can be determined colorimet-rically as the ortho-phosphate ion, P043, in aqueous samples after a reaction that forms an intensely blue-colored derivative. However polyphosphate ions and other ions and compounds containing P do not form this derivative. Total P in a sample can be determined with the same colorimetric procedure after acid hydrolysis and oxidation of all ions and compounds containing P to P04 3. In some elemental analyses the sample is treated with reagents designed to make available for measurement some fraction of an element or elements but not the total amount. For example, a soil sample may be treated with water at pH 3 to simulate the leaching process of acid rain. A total elemental analysis of the filtrate provides information about just those elements solubilized by the mild acid treatment. This can be called the determination of total mild acid leachable elements. 

Most water samples do not require pre-treatment for total elemental analysis, but where organic arsenic or selenium compounds are suspected, pretreatment by digestion with a strong acid mixture, for example, a 3 min sulfuric acid-potassium persulfate digestion or a nitric acid digestion, is necessary. Where pre-concentration is required, cold trapping of the hydrides or liquid-solid extraction has been used but this is very labor intensive when performed offline. 

Most readily mobilised elements such as calcium, phosphorus and potassium must be extracted in acid after pretreatment, often at high temperature (Kamp and Krist, 1988). Total element analysis involves complete... 

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. 

Lim CH and Jackson ML (1982), Dissolution for total elemental analysis. In Page AL, Miller RH and Keeney DR, eds. Methods of Sod Analysis, Part 2, Chemical and Microbiological Properties, second edition, pp. 1-12. American Society of Agronomy Sod Science Society of America, Madison. 

The determination of chemical species in an environmental or biological sample can be difficult and time consuming. The accuracy and precision generally achieved for this type of work is not as good as that for total elemental analysis, even for laboratories with a proven track record in speciation analysis. Only a limited number of high purity standards are available, and so calibration of the method is an important area for improvement in methodology. Standard additions and external calibration strategies have been applied and recently, the use of IDMS has been described. 

An analytical procedure consists of proper sampling, sample storage, if necessary, sample preparation, which is different for total elemental analysis and species analysis, separation procedures, if speciation or preconcentration is required, the quantification step, and quality assurance. All this applies to arsenic analysis and thus will be treated subsequently and demonstrated by practical examples for all these steps. Since speciation for arsenic is of paramount importance, it will be described in some detail. 

In all of these cases the final chars are composed of Si and C only. (2) record the char yield. (3) perform a total elemental analysis and (4) the following calculations are made based on 1 gram of polymer where char yield and % Si are expressed as fractions, and IV is a whole number between 1.5 and 2.5. 

Yamasaki, S. I. (1995). Total elemental analysis of soils by inductively coupled plasma-mass spectrometry (ICP-MS)./4RQ 29(1), 17. 

Total elemental analysis of K and Na has been used extensively to estimate the amount of mica present in a sample free of potassium-feldspars (see Sections BIIIl and BIII2). Micas are dissolved preferentially by Na2S207 fusion (Kiely and Jackson [1965]). In their study, this procedure was applicable to fractions greater than 50 nm in diameter, but in the 2 to 0.2 ixm fraction of a sample, only 68 % of the feldspar was recovered because of dissolution of this mineral. 

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