Monographs: Pharmaceutical substances: Aqua pro injectione - Water for injections
2.2.3 Limit test for heavy metals, procedure 1; determine the heavy metals content according to Method A, allowing to stand for 10 minutes; the colour is not darker than that of 40 mL of the same untreated Water for injections, the pH of which has been similarly adjusted.
Ammonia. Transfer 50 mL to a comparison tube, add 2 mL of alkaline potassio-mercuric iodide TS, and observe down the vertical axis of the tube in diffused light against a white background; the colour produced is not more intense than that of 50 mL of ammonia-free water R with the addition of 2 mL of dilute ammonium chloride TS.
Calcium and magnesium. To 100 mL add 2 mL of ammonium chloride buffer, pH 10.0, TS, 50 mg of mordant black 11 R, and 0.5 mL of disodium edetate (0.01 mol/l) VS; a pure blue colour is produced.
Carbon dioxide. To 25 mL add 25 mL of calcium hydroxide TS; it remains clear.
Chlorides. To 10 mL add 1 mL of silver nitrate (40 g/l) TS and allow to stand for 5 minutes; it remains clear and colourless.
Nitrates. Carefully superimpose 5 mL on 5 mL of diphenylamine/sulfuric acid TS, ensuring that the liquids do not mix; no blue colour appears at the interface of the two liquids.
Sulfates. To 10 mL add 1 mL of barium chloride (50 g/l) TS and allow to stand for 5 minutes; it remains clear and colourless.
Oxidizable matter. To 100 mL add 10 mL of sulfuric acid (~100 g/l) TS and 0.2 mL of potassium permanganate (0.02 mol/l) VS and boil for 3 minutes; the colour is not completely destroyed.
Non-volatile residue. Boil 500 mL on a hot plate or over a flame until the volume is reduced to about 50 mL, then evaporate on a water-bath to dryness. Dry the residue for 1 hour at 105 °C; not more than 5 mg (0.01 mg/mL).
Acidity or alkalinity. To 10 mL add 2 drops of methyl red/ethanol TS; no red colour appears. To a further 10 mL portion add 5 drops of bromothymol blue/ethanol TS; no blue colour develops.
Bacterial endotoxins. Carry out the test as described under
3.4 Test for bacterial endotoxins; contains not more than 0.25 IU of endotoxin RS per mL.