Biomaterial Database

Inorganic phosphate determination: colorimetric assay based on the formation of a rhodamine B-phosphomolybdate complex. 1983

I Debruyne

A sensitive technique for inorganic phosphate determination was developed. It is based on the formation of an insoluble rhodamine B-phosphomolybdate complex. After it is washed with 1 N HCl the precipitate is dissolved in acetone and rhodamine B is measured spectrophotometrically at 555 nm. In 1 N HCl, the complex is composed of three molecules rhodamine B and one molecule phosphomolybdate. Due to the high molar absorbance of rhodamine B in acetone and to the threefold amplification of dye concentration compared to Pi concentration in the precipitated complex, a molar absorption coefficient of 330,000 +/- 5000 M-1 cm-1 (SD) is obtained. This allows the determination of quantities as low as 1.5 nmol Pi with good precision, while quantities as low as 0.5 nmol Pi are detectable. The effect of anions and buffers was studied. Some possible applications of the method are illustrated, as, e.g., enzyme activity measurement at very low substrate concentration and determination of small quantities of Pi and total phosphate in (biological) samples.

UI	MeSH Term	Description	Entries
D008832	Microchemistry	The development and use of techniques and equipment to study or perform chemical reactions, with small quantities of materials, frequently less than a milligram or a milliliter.
D008982	Molybdenum	A metallic element with the atomic symbol Mo, atomic number 42, and atomic weight 95.95. It is an essential trace element, being a component of the enzymes xanthine oxidase, aldehyde oxidase, and nitrate reductase.	Molybdenum-98,Molybdenum 98
D010710	Phosphates	Inorganic salts of phosphoric acid.	Inorganic Phosphate,Phosphates, Inorganic,Inorganic Phosphates,Orthophosphate,Phosphate,Phosphate, Inorganic
D010756	Phosphoric Acids	Inorganic derivatives of phosphoric acid (H3PO4). Note that organic derivatives of phosphoric acids are listed under ORGANOPHOSPHATES.	Pyrophosphoric Acids,Acids, Phosphoric,Acids, Pyrophosphoric
D002621	Chemistry	A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.
D003124	Colorimetry	Any technique by which an unknown color is evaluated in terms of standard colors. The technique may be visual, photoelectric, or indirect by means of spectrophotometry. It is used in chemistry and physics. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
D012235	Rhodamines	A family of 3,6-di(substituted-amino)-9-benzoate derivatives of xanthene that are used as dyes and as indicators for various metals; also used as fluorescent tracers in histochemistry.	Rhodamine
D014966	Xanthenes	Compounds with three aromatic rings in linear arrangement with an OXYGEN in the center ring.	Xanthene
D055598	Chemical Phenomena	The composition, structure, conformation, and properties of atoms and molecules, and their reaction and interaction processes.	Chemical Concepts,Chemical Processes,Physical Chemistry Concepts,Physical Chemistry Processes,Physicochemical Concepts,Physicochemical Phenomena,Physicochemical Processes,Chemical Phenomenon,Chemical Process,Physical Chemistry Phenomena,Physical Chemistry Process,Physicochemical Phenomenon,Physicochemical Process,Chemical Concept,Chemistry Process, Physical,Chemistry Processes, Physical,Concept, Chemical,Concept, Physical Chemistry,Concept, Physicochemical,Concepts, Chemical,Concepts, Physical Chemistry,Concepts, Physicochemical,Phenomena, Chemical,Phenomena, Physical Chemistry,Phenomena, Physicochemical,Phenomenon, Chemical,Phenomenon, Physicochemical,Physical Chemistry Concept,Physicochemical Concept,Process, Chemical,Process, Physical Chemistry,Process, Physicochemical,Processes, Chemical,Processes, Physical Chemistry,Processes, Physicochemical