SPECTROPHOTOMETRIC DETERMINATION OF CALCIUM IN MILK, HAIR AND URINE / 营养学报

ABSTRACT

A spectrophotometric method for the determination of calcium in milk, hair and urine was developed using metal complezing dye orthocresolphth-alein complexone(OCPC).The organic matter in the tested sample was destroyed by digestion. An aliquot of the digested solution was mixed with color developing reagent, alkaline OCPC, cantaining 8-quinolinol to suppress interference such as magnesium, and the absorbance was measured at 570 nm.The coefficients of variation were 0.87, 3.6 and 1.2% for milk, hair and urine samples; and the analytical recoveries of calcium from milk, hair and urine averaged 100.4, 101.0 and 98.5% respectively. The calcium content of milk and hair determined by this method was closely correlated with that of the ICP-AES method (r =0.994, p