AOAC Official Method 931.06 Phosphorus (Total) (P2O5) in Eggs
First Action 1931
Final Action
A. Preparation of Test Solution
(a) Liquid eggs.—From well-mixed test portion, 925.29(a) or (b) (see 34.1.01), accurately weigh, by difference, into 250 mL Pyrex beaker, ca 2 g yolks, 4 g whole eggs, or 10 g whites. Record weight to nearest 0.0001 g. Add 20 mL 10% Na2CO3 (w/v) solution and evaporate to dryness on hot plate or in oven overnight at 100–105°C. Transfer beaker while hot to furnace at 500°C for 1 h. Cool, add few drops H2O, break up residue with flat-end glass rod, and cover beaker with watch glass; slowly add 10 mL HNO3 (1 + 3) while stirring, mix, wash watch glass, and filter, collecting filtrate in 300 or 500 mL Erlenmeyer. Thoroughly wash charred material and filter with H2O.
(b) Dried eggs.—Transfer 1 g well-mixed test portion, 925.29(c) (see 34.1.01), to 150 mL Pyrex beaker, add 20 mL 10% Na2CO3 (w/v) solution, and evaporate to dryness on hot plate or in oven overnight at 100–105°C. Transfer beaker while hot to furnace at 500°C for 1 h. Cool, add few drops water, break up residue with flat-end glass rod, and cover beaker with watch glass; slowly add 10 mL nitric acid (1 + 3) while stirring, mix, wash watch glass, and filter, collecting filtrate in 300 or 500mLErlenmeyer flask. Thoroughly wash charred material and filter with water.
