Stannous Chloride
SnCl2·2H2O 225.65
Tin chloride (SnCl2) dihydrate
[10025-69-1].
(stan' us klor' ide).
SnCl2·2H2O 225.65
Tin chloride (SnCl2) dihydrate
[10025-69-1].DEFINITION
Stannous Chloride contains NLT 98.0% and NMT 102.0% of SnCl2·2H2O.
IDENTIFICATION
• A.
Sample solution:
To 0.40 g of Stannous Chloride add 1 mL of dilute hydrochloric acid solution (236 mL/L of hydrochloric acid), and dilute with water to 20 mL. [Note—Keep a portion for the Limit of Sulfate test. ]
Analysis:
To 1 mL of the Sample solution add a mixture of 5 mL of water and 0.05 mL of mercuric chloride TS.
Acceptance criteria:
A blackish-gray precipitate forms.
• B.
Sample:
1.0 g
Analysis 1:
Dissolve the Sample in 3.0 mL of water. Add 0.5 mL of dilute sodium hydroxide solution (85 mg/mL of sodium hydroxide) to the cloudy solution.
Acceptance criteria 1:
A yellowish, flocculent precipitate is formed.
Analysis 2:
Add 6.5 mL of water to the solution resulting from Analysis 1. To 1.0 mL of the previously shaken suspension add 1.0 mL of sodium hydroxide solution (420 mg/mL of sodium hydroxide).
Acceptance criteria 2:
The precipitate dissolves, and the resulting solution is clear and colorless.
• C. Identification Tests—General, Chloride 
191
191
Sample solution:
Dissolve 10 mg of Stannous Chloride in 2 mL of 20% nitric acid.
Acceptance criteria:
Meets the requirements
ASSAY
• Procedure
Sample:
0.1 g of Stannous Chloride
Titrimetric system
(See Titrimetry 541.)
541.)
Mode:
Direct titration
Titrant:
0.1 N iodine VS
Blank:
50 mL of water
Endpoint detection:
Colorimetric
Analysis:
Dissolve the Sample in 50 mL of water freed from oxygen by purging with carbon dioxide or nitrogen for 15 min prior to the addition. Add 1.5 mL of 0.8 N hydrochloric acid, 5 g of potassium sodium tartrate, 10 g of sodium bicarbonate, and 1 mL of starch TS. Titrate the resulting solution immediately with Titrant. Perform a blank determination.
Calculate the percentage of stannous chloride (SnCl2·2H2O) in the Sample:
Result = {[(VS 
VB) × N × F]/W} ×100
VB) × N × F]/W} ×100| VS | = | = Titrant consumed by the Sample (mL) |
| VB | = | = Titrant consumed by the Blank (mL) |
| N | = | = actual normality of the Titrant (mEq/mL) |
| F | = | = equivalency factor, 112.8 mg/mEq |
| W | = | = Sample weight (mg) |
Acceptance criteria:
98.0%–102.0%
IMPURITIES
• Limit of Sulfate
Acetic acid solution:
Dilute 30 mL of glacial acetic acid with water to 100 mL.
30% alcohol:
Dilute 30 mL of alcohol with water to 100 mL.
Potassium sulfate solution:
1.8 mg/mL of potassium sulfate in 30% alcohol
Standard solution:
Mix 3 mL of barium chloride solution (250 mg/mL) and 4.5 mL of Potassium sulfate solution. Shake, and let stand for 1 min. To 2.5 mL of this solution add 15 mL of Potassium sulfate solution and 0.5 mL of Acetic acid solution. Allow to stand for 5 min.
Sample solution:
Use 15 mL of the Sample solution prepared as directed in Identification test A.
Analysis:
Mix 3 mL of barium chloride solution (250 mg/mL) and 4.5 mL of Potassium sulfate solution. Shake, and let stand for 1 min. To 2.5 mL of this solution add the Sample solution and 0.5 mL of Acetic acid solution. Allow to stand for 5 min.
Acceptance criteria:
Any opalescence in the Sample solution is not more intense than that in the Standard solution (500 ppm).
• Limit of Iron
Standard iron solution:
Prepare as directed under Iron 241, Special Reagents.
241, Special Reagents.
Standard solution:
Immediately before use, dilute 1 mL of Standard iron solution with water to 10 mL. This solution contains the equivalent of 1 µg/mL of iron.
Sample solution:
Dilute 5 mL of the Sample solution prepared as directed in Substances Not Precipitated by Thioacetamide with water to 10 mL.
Analysis:
To 10 mL each of the Standard solution and the Sample solution add 2 mL of dilute citric acid (200 mg/mL) and 0.1 mL of thioglycolic acid, and mix. Make alkaline with a dilute ammonia solution (620 mL/L of ammonium hydroxide). Dilute with water to 20 mL. Allow the treated Standard solution and the treated Sample solution to stand for 5 min.
Acceptance criteria:
Any pink color in the Sample solution is not more intense than that in the Standard solution (100 ppm).
• Limit of Lead
Dilute thioacetamide solution:
[Note—Prepare immediately before use. ] To 0.2 mL of thioacetamide TS add 1 mL of a mixture of 5 mL of water, 15 mL of 1 N sodium hydroxide, and 20 mL of 85% glycerin. Heat in a water bath for 20 s.
Standard lead solution:
Prepare as directed under Heavy Metals 231, Special Reagents.
231, Special Reagents.
Standard solution:
On the day of use, mix 1.0 mL of Standard lead solution, 6 mL of water, 3 mL of sodium hydroxide solution (420 mg/mL of sodium hydroxide), and 0.5 mL of Dilute thioacetamide solution.
Sample solution:
Dissolve 1.0 g of Stannous Chloride in 2 mL of a mixture of nitric acid and hydrochloric acid (1:3). Heat the solution on a water bath until nitrous vapor is no longer evolved. Dissolve the residue in water, and dilute with water to 25 mL. To 5 mL of this solution add 3 mL of sodium hydroxide solution (420 mg/mL of sodium hydroxide) and 2 mL of water. Heat until a clear solution is obtained, and cool. Add 0.5 mL of Dilute thioacetamide solution, and allow to stand for 2 min.
Analysis:
Compare the Standard solution and the Sample solution.
Acceptance criteria:
Any color in the Sample solution is not more intense than that in the Standard solution (50 ppm).
SPECIFIC TESTS
• Appearance of Solution
Standard stock solution:
Pipet 30.0 mL of ferric chloride CS, 30.0 mL of cobaltous chloride CS, and 24.0 mL of cupric sulfate CS into a 100-mL volumetric flask. Dilute with 1% (w/v) hydrochloric acid to volume.
Standard solution:
Dilute 1.0 mL of the Standard stock solution with 1% (w/v) hydrochloric acid to 100 mL.
Sample solution:
Dissolve 10.0 g of Stannous Chloride in dilute hydrochloric acid solution, and dilute with dilute hydrochloric acid solution to 20 mL.
Acceptance criteria:
The Sample solution is clear and colorless, or if not, not more intensely colored than the Standard solution.
• Substances Not Precipitated by Thioacetamide
Sample solution:
Dissolve 1.0 g of Stannous Chloride in dilute hydrochloric acid solution, and dilute with the same acid to 30 mL. Heat to boiling. Add 30 mL of thioacetamide TS, and boil for 15 min to produce Solution A. Filter 5 mL of Solution A, and heat the filtrate to boiling. Add 5 mL of thioacetamide TS, and boil for 15 min. If a precipitate is formed, add the remainder of Solution A to the mixture to produce Solution A1. Add 10 mL of thioacetamide TS, and boil. Repeat the series of operations from “Filter 5 mL” until a precipitate is no longer formed on addition of thioacetamide TS to the filtrate obtained from the 5 mL of Solution A (Solution A1, Solution A2, and so on, respectively). If no precipitate is formed, or if no more precipitate is formed, combine the solution obtained with the remainder of Solution A (Solution A1, Solution A2, and so on, respectively), filter, and wash the precipitate with 10 mL of water. Heat the filtrate until the resulting vapor no longer turns a moistened piece of lead acetate test paper blackish-gray. Allow to cool, and dilute with water to 50 mL. [Note—Keep a portion for the Limit of Iron test. ]
Analysis:
Evaporate 25 mL of the Sample solution to dryness, and ignite at 600
.
.
Acceptance criteria:
The residue weighs NMT 1 mg (0.2%).
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers. No storage requirements specified.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Robert H. Lafaver, M.S.
Scientific Liaison 1-301-816-8335 |
(EXC2010) Monographs - Excipients |
USP35–NF30 Page 1970
Pharmacopeial Forum: Volume No. 33(5) Page 978