Major metals

Considering additionally that the risk assessment of mixtures is presently an urgent issue, and that usually mixtures of exclusively organic chemicals or exclusively metals are investigated, in future more emphasis should be placed on the interactions of xenobiotic HIOCs with metals. Major research questions will include how these interactions influence bioavailability of both metals and HIOCs, interactions with biological membranes, uptake, and common toxic effects. 

METAL MAJOR SOURCE(S) HEALTH EFFECT(S) DRINKING WATER STANDARDS ... 

Total heavy metals Major constituents Heavy metals 28-1820 755... 

OD-R (fresh cut grass, grassy, leafy, metallic) [major damaged leaf green odour insect attractant] OD-R (floral, fruity)... 

Six nonmetallic major bioelements or macroelements are needed to form the multitude of macromolecules in a living cell (C, O, H, N, P, S), and four additional metals to neutralize the predominantly negative charges of these macromolecules (K, Mg, Ca, Na). While the elements from carbon to calcium are undisputed major bioelements, some authors may remove sodium (Na) from this list and insert iron (Fe) instead. However, iron - like most trace elements - is a transition element, whereas sodium is an element of a major group of the periodic system like the other three metallic major bioelements. 

Heavy Metals, Major Metals, Trace Elements... 

The development of studies linked with heavy metals, major metals, and trace metals is of great concern, not only from an analytical viewpoint but also from an environmental one, considering many of these elements can produce severe injuries to human health. A large variety of analytical methods and techniques exist, and are available in a relatively easy way. It is necessary to clearly know several particular conditions of the sample to be treated as well as on the available facilities to select the adequate technique to be used for. So, factors such as the concentration range of the analyte, the precision required, the amount of sample available, or purposes of the analysis must be considered to carry out this selection of analytical technique. 

Lundin (1970), in an investigation of the formation of samarium-type structure in intra rare earth binary alloys included six compositions in the lanthanum-scandium system ranging from 10 to 85at% La. Lundin prepared his alloys using 99.8(wt )% pure lanthanum metal (major impurities, 330 ppm other rare earths, 510 ppm O, 50 ppm each Si, Mg and Zn) and 99 -F (wt )% pure scandium for which there were no details given on the impurities. Lundin found two-phase inuniscibility at low temperatures in the lanthanum-scandium system and, since no samarium-type structure was found, he concluded that scandium behaves more like the neighboring transition elements than it does as a rare earth metal. 

Metals Major Use Activation Method Hydrogenation Acitivy... 

Marcovecchio, J. E., Botte, S. E., Freije, R. H. Heavy Metals, Major Metals, Trace Elements. In Handbook of Water Analysis. Nollet, L. M., Ed., London CRC Press London, 2007,275-311. 

---