Sodium triphosphate, complexing

The category of builders consists predominantly of several types of materials -specific precipitating alkaline materials such as sodium carbonate and sodium silicate complexing agents like sodium triphosphate or nitrilotriacetic acid (NTA) and ion exchangers, such as water-soluble polycarboxylic acids and zeolites (e.g., zeolite A). 

The method using pH determinations, for example, depends on the fact that the pH of a solution of sodium triphosphate is decreased by the addition of salts containing the cation under investigation—c.g., NaCl or CaCl2 95, 248, 345). The quantity of H+ ions set free in this way is determined potentiometrically and the formation constant of the complex is determined on the basis of the equilibria involved, such as ... 

Condensed polyphosphates such as sodium triphosphate are of great industrial importance since they arc used in large tonnages as "builders" in the manufacture of detergents. As such they function to adjust the pH and to complex water-hardening ions such as Ca2+ and Mg2+.17 Industrially, sodium triphosphate is rot made from the reaction of Eq. 16.12 but from dehydration of sodium hydrogen phosphate and sodium dihydrogen phosphate mixtures ... 

A widely applicable masking agent is sodium triphosphate, Na5P3Oi0-6H2O, which readily complexes with a very wide variety of cations in all groups of the Periodic Table, preventing their precipitation by alkali hydroxide, ammonia, phosphate, carbonate or borate. It is used commercially as Calgon to mask calcium which cannot then form precipitates with citrate, fluoride or oxalate ions and in many other instances (see Table 3). 

Sodium triphosphate is used almost solely in one type of product detergents. Some detergents contain up to 50% by weight sodium triphosphate. It has the unique property of complexing or sequestering dipositive ions such as calcium (Ca2+) and magnesium (Mg2+) that are present in water. Tide is an example of a phosphate detergent that has been used for at least 5 decades. 

The builders include complexing agents such as sodium triphosphate, ion exchangers such as Zeolite A, and washing alkalies such as sodium carbonate and sodium silicate. 

Anderson et al. (1963) have described a more comprehensive system for nucleotide analysis. Their system has been recommended for adaptations of some amino acid analysers. A single column 0.9 X 160 cm of Dowex-1 ( x8, 200- 00 hydraulically fractionated to about 60 p particle diameter) washed in acid and alkali was packed in sections in 0.15 M sodium acetate pH 4.4. The sample, vol 0.5-1.5 ml in buffer, was eluted by a 1.4-1 linear gradient from 0.15-3 M sodium acetate at a constant pH (4.4), flow-rate (1 ml/min) and temperature (40°C). The first few peaks were extremely sharp and a lower flow rate could be used here. Good separations of quite complex mixtures were obtained in 28 hr. The triphosphates, UTP, ATP, GTP could be separated more quickly (in 6 hr) on a 0.9 x 50 cm column of the same resin eluted with a 1 1 linear gradient from 0.5 M sodium acetate, 0.25 M NaCl to 1.0 M sodium acetate, 0.5 M NaCl pH 3.6 at 1.7 ml/min at room temperature. A freshly packed column was used for each determination in both cases. 

X. Addition to zinc sulfate results in the precipitation of zinc pyrophosphate and the formation of a complex sodium zinc triphosphate. Formation of both of thcs( substances is accompanied by liberation of hydrogen ions, Tltntion with sodium hydroxide, therefore, effects neutralization of sulfuric acitTUberated by both pyrophosphate and triphosphate. 

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