A fast, simple and reliable method for the microdetermination of phosphorus in biological materials

✍ Scribed by W.R. Morrison

• Publisher: Elsevier Science
• Year: 1964
• Tongue: English
• Weight: 408 KB
• Volume: 7
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(64)90231-3

✦ Synopsis

The determination of phosphorus is one of the basic determinations in biochemical analyses, yet, when a simple, rapid and sensitive method was required for the determination of phosphorus in wheat lipids, standard existing methods were not found to be entirely satisfactory. These methods are based on the destruction of organic matter by wet oxidation, liberating phosphoric acid, formation of a phosphomolybdic acid complex which is quantitatively reduced to a heteropoly blue color, and measurement of the color by spectrophotometry.

The usual disadvantages of the method and its numerous modifications include the need for large samples, prolonged digestion procedures to destroy organic matter, instability of some reagents, and fading of the heteropoly blue color. These disadvantages are not all common to every modification of the method. This paper describes a revised method which eliminates them all, giving a method that is both rapid and reliable. Although developed for lipid materials which are difficult to digest, the method is applicable to all biological material. METHODS Crude wheat lipids were obtained by extracting commercial wheat flour with methanol and methanol-chloroform

(1). The isolated lipids were redissolved in diethyl ether, so that 1 ml contained about 20 ,ug phosphorus. Deionized water was used for making all other solutions.

Reagents

Analytical grade reagents were used throughout. Sulfuric acid, spgr. 1.84, not less than 98% H&SO,. Hydrogen peroxide, 30% (w/v) solution. Sodium sulfite, 33% (w/v) solution of NazSOj *7H20. Ammonium paramolybdate, 2% (w/v) solution of (NH,),Mo,O,,*4H,O.

Ascorbic acid.