A method for the concentration and for the colorimetric determination of nanomoles of inorganic pyrophosphate

✍ Scribed by Jukka K. Heinonen; Sirpa H. Honkasalo; Eila I. Kukko

• Publisher: Elsevier Science
• Year: 1981
• Tongue: English
• Weight: 689 KB
• Volume: 117
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(81)90725-9

✦ Synopsis

A generally applicable, inexpensive, and sensitive method for the determination of inorganic pyrophosphate (PPJ was developed. PPi was quantitatively separable from solution even in nanomolar concentrations by filtration through a membrane filter in the presence of CaCl* and KF. The separated #'Pi was dissolved by immersing the filter in 0.5 N HSO,. Inorganic phosphate (Pi) was removed by precipitating it as a phosphomolybdate-triethylamine complex and the PP, was measured as a green pyrophosphomolybdate in the presence of 2-mercapmethanol. Nucleotides and phosphate esters do not react. PP, can be accurately assayed even when there is a 104-fold excess of Pi. Trimetaphosphate, tripolyphosphate, and tetrapolyphosphate also give this green color, but the rate of the color formation is 50 times slower than that with PP,. Thus this interference of the polyphosphates can be. eliminated or the polyphosphates can be assayed simultaneously with the PPi in the same sample.