AOAC Official Method 941.19 Elixir of Five Bromides
First Action 1941
Final Action
A. Preparation of DilutionFirst Action 1941
Final Action
Transfer 50 mL laboratory sample to 1 L volumetric flask, dilute to volume, and mix. Measure aliquots of this dilution at original temperature
of sample.
B. Determinations
(a) Ammonium bromide.—Place 200 mL aliquot of dilution in Kjeldahl flask; add small piece of paraffin and excess 10% NaOH solution (w/v) (ca 5 mL). Distil NH3 into excess standard acid [40 mL 0.05M H2SO4, 890.01 (see A.1.14), usually is enough]. Titrate excess acid with 0.1M NaOH, 936.16 (see A.1.12), using methyl red. 1 mL 0.05M acid = 0.00979 g NH4Br.
(b) Calcium bromide.—Pipet 100 mL aliquot of dilution into casserole or Pt dish and evaporate to dryness. Ignite at dull red (ca 525°C) until organic matter is thoroughly charred. Cool, add 5 mL HCl (1 + 3) to dissolve calcium salts, filter, and wash well with hot H2O. Return filter and unoxidized C to casserole or dish and ignite at 600°C until residue is white. Treat residue with 5mLHCl (1 + 3), filter, and wash with hot H2O, combining filtrates.
Determine Ca as in 910.01 (see 3.3.02), and reserve filtrate for determination of Na, K, and Li. If 0.1M KMnO4, 940.35 (see A.1.10), is used, 1 mL = 0.0100 g CaBr2.
