Biological elements, table

A selected list of reference materials (sediments as well as biological tissues) distributed by several Canadian, U.S., and E.U. sources shows a wide range of solid samples that could be used for comparative analysis of major organic elements (Table 4.2). These materials are widely available and have been analyzed for at least some constituents. In addition, these materials are homogeneous and can be expected to exhibit stable compositions over time. All of the thirty or so listed reference materials,... 

Multifaceted aspects of research on biomedical polymers are shown in Table 1. End-use devices are manufactured starting from their original concept. To approach the target, materials design is carried out so that the materials can exhibit the desirable property when they are brought into contact with any particular biological element. Fundamental studies are carried out in order to elucidate structure-property relationships in the interaction of materials with biological elements. 

Biocompatibility (See Table 1), which is a phenomenological concept, is the essential property of biomaterials. For instance, the inner surface of an implanted vascular graft or blood pump (artificial heart) must be blood-compatible, while its outer surface must be tissue-compatible. In other words, the material surfaces must not exert any adverse elfects upon blood or tissue, or upon other biological elements at the interfaces. 

Zinc is one of the more abundant trace elements (Table 1), and its essential role in biological processes is now well established. Over 100 enzymes require zinc for activity, even though only a relatively small number of these have been well studied. Examples are listed in Table 12. In this discussion most attention will be paid to the well-characterized zinc enzymes, but it must be stressed that there is increasing interest in other aspects of the biological chemistry of zinc, notably... 

Four essential elements, Ft, O, C, and N, comprise more than 99 atom % and about 96 wt % of the human body. These 4 and 14 other essential elements occur among the first 30 elements (through zinc) of the periodic table. (Uncertainties surround the status of chromium (see Chromium Biological Relevance). ) Three heavier trace elements Se, Mo, and I are also essential in humans. For 17 tabulated essential elements, Table 1 shows the predominant elemental form at pH 7, typical adult concentrations in the blood plasma or serum, the approximate amount found in a 70-kg adult, and a recommended adult daily allowance. In addition to... 

Grey hair indicates a change in hair structure. The biological processes in white hair seem to occur differently than in pigmented hair. This finds expression in a lower concentration of trace elements (Table 1). Hence, a hair sample should be made up of evenly pigmented hair, with hair... 

Biological Elements classified according to Position in the Periodic Table... 

The periodic table can be divided into three regions by means of two lines. Invariable biological elements, with the exception of Be, are those above the upper line variable elements occur between the lines and ultra-micro and non-biological elements lie below the continuous line. 

Fig. 1. Periodic Table showing elements of importance in biological systems principal element of bioorganic compounds essential mineral nutrients for humans and other animals 1 essential mineral nutrient for animals, probably for humans M present in body, not known to be a nutrient or toxic element M element used in medicine element generally poisonous and present in body, possibly toxic.

Miscellaneous. Trace analyses have been performed for a variety of other materials. Table 9 Hsts some uses of electrothermal atomic absorption spectrometry (etaas) for determination of trace amounts of elements in a variety of matrices. The appHcations of icp /ms to geological and biological materials include the following (165) ... 

Figure 22. Correlations between the interfacial term, AX, derived from Fig. 14, and the enthalpy of formation of the oxide MO, corrected for the work to break metal-metal bonds. I, II, in mean first, second, and third periods of the periodic table of elements. From Ref. 26, updated. (From R. Guidelli, ed, Electrified Interfaces in Physics, Chemistry, and Biology, p. 252, Fig. 3. Copyright 1992 Kluwer Academic Publishers. Reproduced with permission.)...

Almost all elements in the periodic table are involved in at least one way or another in the biological cycle of the ocean. Many elements are essential or required nutrients. Others are carried along as passive participants. In either case the rates of biological processes need to be known. 

The chemistry, and hence hazards, of hot, or radioactive, elements parallels that of their cold isotopes. However, the radiation poses additional toxicity hazards. A qualitative classification of selected isotopes in terms of their toxicity is given in Table 10.2. The biological effects of ionizing radiation stem mainly from damage to individual cells following ionization of the water content. Oxidizing species, e.g. hydrogen peroxide. 

The concept of an octet of electrons is one of the foundations of chemical bonding. In fact, C, N, and O, the three elements that occur most frequently in organic and biological molecules, rarely stray from the pattern of octets. Nevertheless, an octet of electrons does not guarantee that an inner atom is in its most stable configuration. In particular, elements that occupy the third and higher rows of the periodic table and have more than four valence electrons may be most stable with more than an octet of electrons. Atoms of these elements have valence d orbitals, which allow them to accommodate more than eight electrons. In the third row, phosphoms, with five valence electrons, can form as many as five bonds. Sulfur, with six valence electrons, can form six bonds, and chlorine, with seven valence electrons, can form as many as seven bonds. 

Table 3.6 presents examples for environmental and biological natural matrix CRMs from BCR, NIST and NRCC certified for elements using the above described analytical multi-method approaches. 

---