Rapid Separative Determination of Orthoand Polyphosphates in Foods

Abstract

Rapid determination method of various phosphates in several kinds of foods were developed. Five grams of homogenized sample were defatted with 10ml of ethylether, and extracted twice with 10 and 5ml of ice-cold 20% trichloroacetic acid solution while cooling for 1min by using test tube shaker and filtered through cotton plug. The Filtrates were mixed and made up to 20ml. One ml of the extracted solution was neutralyzed with 1N NaOH and diluted with 300ml of 5 mM EDTA·2Na-EDTA·4Na solution (pH 5.0). This solution was poured into anion exchange column (Dowex 1×4, 100-200 mesh, chloride form, 1×8cm) and the column was washed with 30ml of the above 5mM EDTA solution. The ortho-, pyro-, tri- and another poly-phosphates were separatively eluted with 50ml of 0.09, 0.19 and 0.30M KCl in 5mM EDTA solution, and 50ml of 2N HCl solution. Ten ml of each eluate was added with 1ml of 1.5% ammoniummolybdate·HCl solution and heated for 10min in boiling water bath and after adding with 1ml of 1% hydrazize-sulfate again heated for 10min, then absorbance at the wavelength of 830nm was measured. Recovery of phosphate and polyphosphates were 69.3-104% within the addition level of 0.02-2%.