Orthophosphate, organophosphorus

Phosphorus from organophosphorus compounds, which are combusted to give mainly orthophosphate, can be absorbed by either sulphuric acid or nitric acid and readily determined spectrophotometrically either by the molybdenum blue method or as the phosphovanadomolybdate (Section 17.39). 

Absorbance detectors are also commonly used in combination with postcolumn reactors. Here, most issues of detector linearity and detection limit have to do with optimization of the performance of the reactor. In a typical application, organophosphorus compounds with weak optical absorbances have been separated, photolyzed to orthophosphate, and reacted with molybdic acid, with measurement being performed by optical absorbance.58... 

I. S. Kulaev, L. A. Okorokov, Fen-Yui-Tsyan and G. A. Kuritsyna (1966b). Organophosphorus compounds in Penicillium chrysogenuin, the phosphorus of which is determined as orthophosphate (in Russian). Dokl. Akad. Nauk SSSR, 171, 473 -75. 

Very little detail is known about the nitrogen and phosphorus cycles. Dissolved orthophosphate is taken up in plant growth and returned eventually after serving in cell fluids and tissues. It appears to be released primarily in the form of organophosphorus compounds, and at certain seasons of the year more than half the phosphorus in the water is described as "dissolved organic phosphorus. Yet as of a year or so ago... 

Most chemical methods for the analysis of organophosphorus compounds involve the initial decomposition and conversion of the P into orthophosphate which can then be analysed by the chemical methods outlined above. Preliminary procedures are, however, often essential and are frequently highly specific to the particular analytical problem involved. These procedures can involve extraction, cleanup, separation and identification, which frequently incorporate the use of physical methods. 

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