DETERMINATION OF CALCIUM AND PHOSPHORUS IN MILK

A fast, accurate method for determining Ca and P in milk was developed. A 1‐ml samples of milk was ashed without pre‐drying for 1 h and the diluted HCl extract was used for the determination of Ca by atomic absorption spectroscopy and P by colorimetry with measurement of the phosphomolybdenum blue complex at 880 nm for maximum sensitivity. Results were in good agreement with those found for 2 h ashing with or without the preliminary step for evaporating to dryness prior to ashing. Recovery ranged fiom 101.3 to 102.0% for Ca and 99.1 to 100.1 % for P when 1 ml sample of milk was spiked with a 1‐ml aliquot of a CaHPO4 standard solution and analysed by the method. The method had a precision of approximately 1.0 % coeficient of variation for both Ca and P in milk and in the CaHPO4 standard solution. Copyright © 1990 John Wiley & Sons, Ltd