1.0) Description: Greenish-grey powder, very hygroscopic.
2.0) Solubility: Freely soluble in water, slightly soluble in methanol, practically insoluble in
ethanol (96 per cent).
3.0) Identification:
- A. Add several drops of dilute ammonia R2 1 mL of solution S . A blue precipitate is formed, On further addition of dilute ammonia R2 the precipitate dissolves and a dark blue colour is produced.
- B. Loss on drying .
- C. Dilute 1 mL of solution S to 5 mL with water R.
The solution gives reaction (a) of sulfates .
4.0) Tests:
4.1) Solution S
Dissolve 1.6 g.in water R and dilute to 50 mL with the same solvent.
4.2) Appearance of solution
Solution S is clear .
4.3) Chlorides
Maximum 150 ppm.
Dilute 10 mL of solution S to 15 mL with water R.
4.4) Iron
Maximum 150 ppm.
Atomic absorption spectrometry .
Test solution Dissolve 0.32 g in 10 mL of water R, add 2.5 mL of lead-free nitric acid R and
dilute to 25.0 mL with water R.
Reference solutions Prepare the reference solutions using iron standardsolution (20 ppm Fe)
R, adding 2.5 mL of lead-free nitric acid R and diluting to 25.0 mL with water R.
Source Iron hollow-cathode lamp.
Wavelength 248.3 nm.
Atomisation device Air-acetylene flame.
Copper may form explosive acetylides with acetylene. Therefore, clean the burner
thoroughly before any residues become dry.
4.5) Lead
Maximum 80 ppm.
Atomic absorption spectrometry .
Test solution Dissolve 1.6 gin 10 mL of water R, add 2.5 mL of lead-free nitric acid R
and dilute to 25.0 mL with water R.
Reference solutions Prepare the reference solutions using lead standard solution
(l00 ppm Pb) R, adding 2.5 mL of lead-free nitric acidRand diluting to 25.0 mL with water R.
Source Lead hollow-cathode lamp.
Wavelength 217.0 nm.
Atomisation device Air-acetylene flame.
Copper may form explosive acetylideswith acetylene. Therefore, clean the burner
Thoroughly before any residues become dry.
4.6) Loss on drying
Maximum 1.0 per cent, determined on 0.500 g by drying in an oven at 250 ± 10 “C.
4.7) Assay
Dissolve 0.125 gin: 50 mL of water R. Add 2 mL of sulfuric acid Rand 3 g of potassium
iodide R. Titrate with 0.1 M sodium thiosulfate, using 1 mL of starch solution R towards
the end of the titration.
1 mL 0.1 M sodium thiosulfate is equivalent to 15.96 mg of CuSO4.