1970, ISBN: 9781158396948

Purchase includes free access to book updates online and a free trial membership in the publisher's book club where you can select from more than a million books without charge. Not illus… More...

Purchase includes free access to book updates online and a free trial membership in the publisher's book club where you can select from more than a million books without charge. Not illustrated. Excerpt: 89 °C (hydrate) Phosphotungstic acid (PTA), tungstophosphoric acid (TPA), is a heteropoly acid with the chemical formula H3PW12O40. It normally present as a hydrate. EPTA is the name of ethanolic phosphotungstic acid, its alcohol solution used in biology. It has the appearance of small, Purchase includes free access to book updates online and a free trial membership in the publisher's book club where you can select from more than a million books without charge. Not illustrated. Excerpt: 89 °C (hydrate) Phosphotungstic acid (PTA), tungstophosphoric acid (TPA), is a heteropoly acid with the chemical formula H3PW12O40. It normally present as a hydrate. EPTA is the name of ethanolic phosphotungstic acid, its alcohol solution used in biology. It has the appearance of small, colorless-grayish or slightly yellow-green crystals, with melting point 89 °C (24 H2O hydrate). It is odorless and soluble in water (200 g/100 ml). It is not especially toxic, but is a mild acidic irritant. The compound is known by a variety of different names and acronyms (see 'other names' section of infobox). In these names the "12" or "dodeca" reflects the fact that the anion contains 12 tungsten atoms. Some early workers who did not know the structure, such as Hsien Wu, called it phospho-24-tungstic acid, formulating it as 3H2O. P2O5 24WO3.59H2O, (P2W24O80H6).29H2O, which correctly identifies the atomic ratios of P, W and O. This formula was still quoted in papers as late as 1970. Phosphotungstic acid is used in histology as a component for staining of cell specimens, often together with haematoxylin as PTAH. It binds to fibrin, collagen, and fibres of connective tissues, and replaces the anions of dyes from these materials, selectively decoloring them. Phosphotungstic acid is electron dense, opaque for electrons. It is a common negative stain for viruses, nerves, polysaccharides, and other biological tissue materials for imaging by a transmission electron microscope. Structure of the phosphotungstate anionGouzerh summarises the historical views on the structure of phosphotungstic acid leading up to Keggin's determination of the structure as: The structure was determined by J.F Keggin first published in 1933and then in 1934 and is general. More: Books, , Heteropoly-Acids~~Books-Llc, , , , , , , , , , General Books LLC<