Graphite-Furnace Atomic Absorption Spectrometric Determination And Survey Of Total Aluminum, Copper, Manganese, Molybdenum, And Tin In Infant Formulas And Evaporated Milks

Abstract

Abstract A graphite-furnace atomic absorption spectrometric (GFAAS) method using a single simple digestion was developed to determine aluminum, copper, manganese, molybdenum, and tin in infant formulas and evaporated (evap.) milks. Citric acid (0.5 mL 20%) and 3 mL HNO3 were added to 2 g formula (ready-to-use basis) in unwashed polystyrene test tubes. Tubes were capped, and solutions were digested 6-18 h at 55C. Digests were diluted to 10 mL with water and analyzed. Standards were prepared in a matrix of 30% HNO3 and 1% citric acid without digestion. Palladium (1 μg) was used as matrix modifier for aluminum and tin determinations. The mean detection limits of the method were 0.021,0.043, 0.006, 0.063, and 0.073 μg/g for aluminum, copper, manganese, molybdenum, and tin, respectively. The elements were determined in 191 Canadian infant formulas and evap. milk samples. Means, medians, and ranges (μ/g) of metals in soy-based ready-to-use formulas were as follows: 1.62, 0.54, and 0.23-5.2 for aluminum; 0.87,0.88, and 0.71-1.14 for copper; 0.63,0.22, and 0.042-2.4 for manganese; 0.068, <0.049, and <0.048-0.14 for molybdenum; and 0.20, 0.15, and <0.074-0.54 for tin. Means, medians, and ranges (μg/g) of metals in milk-based ready-to-use formulas were as follows: 0.18,0.13, and <0.011-0.66 for aluminum; 0.61, 0.58, and 0.44-0.93 for copper; 0.097,0.094, and 0.053- 0.16 for manganese; 0.033, <0.042, and <0.012- 0.067 for molybdenum; and 0.23,0.18, and 0.067-0.91 for tin. Respective levels in evap. milks (as sold) were as follows: 0.08, 0.051, and <0.017- 0.27 for aluminum; 0.103, 0.087, and 0.045-0.31 for copper; 0.071, 0.062, and 0.048-0.16 for manganese; 0.14, <0.17, and <0.07-<0.19 for molybdenum; and 2.84,0.46, and 0.032-48 for tin.