Metaphosphate
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Template:Cleanup A metaphosphate is a salt or an ester of metaphosphoric acid, HPO3. Metaphosphates are condensation products of orthophosphoric acid (H3PO4) with the sum formula (M'PO3)n, where n=1, 2, 3, ..., (M': univalent cation). In contrast to polyphosphates, metaphosphates store themselves to ring molecules together. As an example the 6-Ring of the trimetaphosphate is represented. Tetrametaphosphates form a similar 8-Ring.
Trimetaphosphates were used in former times in detergents; today due to the fertilization effect of the phosphates zeolites (stand silicates, as e.g. zeolite A) are used.
Sodium metaphosphates
Although sodium metaphosphate is the general term for any polyphosphate salt with four or more phosphate units, the four-phosphate unit version of sodium metaphosphate has been used commercially as an oral care agent; i.e., a chelating agent in cosmetic formulations.[1] The four-phosphate unit version is cyclic.[1]
Sodium trimetaphosphate has served as a buffering agent and sodium hexametaphosphate as a corrosion inhibitor.[1] Both of these sodium metaphosphates are staight chains.[1] Because of the corrosive nature of each of these sodium metaphosphates, these ingredients can be used safely if each formulation is prepared to avoid skin irritation.[1]
References
Sources
http://translate.google.com/translate?sourceid=navclient-menuext&hl=en&u=http%3A//de.wikipedia.org/wiki/Metaphosphate (in English)
Von „http://de.wikipedia.org/wiki/Metaphosphate“ (German page)