Zinc Carbonate USP Grade Specifications:
3Zn(OH)2-2ZnCO3 --- 548.96
Basic zinc carbonate;
Zinc subcarbonate CAS 5263-02-5

DEFINITION
Zinc Carbonate contains the equivalent of NLT 70.0% of zinc oxide (ZnO).

This 70% ZnO is equivalent to 56.1% Zinc content. We can also offer Zinc Carbonate of minimum 60% Zinc content.

IDENTIFICATION
A. Identification Tests—General, Zinc.

ASSAY
Procedure
Analysis: Transfer 2.0 g to a 125-mL conical flask, add 50.0 mL of 1 N sulfuric acid and swirl to dissolve. Add 3 drops of methyl orange and titrate with 1 N sodium hydroxide to a yellow endpoint. Each mL of 1 N sulfuric acid is equivalent to 40.69 mg of zinc oxide (ZnO).
Acceptance criteria: NLT 70.0%

Chloride and Sulfate
Chloride:
Sample solution: Dissolve 1.0 g in a mixture of 20 mL of water and 3 mL of nitric acid.
Acceptance criteria: The Sample solution shows no more chloride than corresponds to 0.03 mL of 0.02 N hydrochloric acid (0.002%).
Sulfate:
Sample solution: Dissolve 10.0 g in a mixture of 75 mL of water and 10 mL of hydrochloric acid, and filter. Neutralize the filtrate with ammonium hydroxide and dilute with water to 100 mL.
Analysis: To 10.0 mL of the Sample solution add 1 mL of 0.6 N hydrochloric acid and 1 mL of barium chloride and allow to stand for 10 min.
Acceptance criteria: The Sample solution shows no more turbidity than that produced in a solution containing 0.10 mL of 0.02 N sulfuric acid and the same quantities of reagents used to prepare the Sample solution (0.01%).