Calcium Gluconate Tablets
Calcium Gluconate Tablets contain NLT 95.0% and NMT 105.0% of the labeled amount of calcium gluconate (C12H22CaO14).
•  A. Identification Tests—General, Calcium 191
Sample stock solution:  A warm, filtered solution in water, equivalent to 100 mg/mL of calcium gluconate from powdered Tablets
Sample solution:  Equivalent to 20 mg/mL of calcium gluconate from a dilution of the Sample stock solution
Acceptance criteria:  Meet the requirements
•  B. Thin-Layer Chromatographic Identification Test
Standard solution:  10 mg/mL of USP Potassium Gluconate RS
Sample solution:  Equivalent to 10 mg/mL of calcium gluconate from a dilution of the Sample stock solution obtained from Identification test A
Chromatographic system 
Adsorbent:  0.25-mm layer of chromatographic silica gel
Application volume:  5 µL
Developing solvent system:  Alcohol, ethyl acetate, ammonium hydroxide, and water (50:10:10:30)
Spray reagent:  Dissolve 2.5 g of ammonium molybdate in 50 mL of 2 N sulfuric acid in a 100-mL volumetric flask, add 1.0 g of ceric sulfate, swirl to dissolve, and dilute with 2 N sulfuric acid to volume.
Samples:  Standard solution and Sample solution
Develop until the solvent front has moved about three-fourths of the length of the plate. Remove the plate, and dry at 110 for 20 min. Allow to cool, and spray with Spray reagent. Heat the plate at 110 for about 10 min.
Acceptance criteria:  The principal spot of the Sample solution corresponds in color, size, and RF value to that of the Standard solution.
•  Procedure
Sample:  A portion of the powder from NLT 20 finely powdered Tablets, equivalent to 500 mg of calcium gluconate
Blank:  Proceed as directed in the Analysis, without the Sample.
Titrimetric system 
Mode:  Direct titration
Titrant:  0.05 M edetate disodium VS
Indicator:  Hydroxy naphthol blue, 300 mg
Endpoint detection:  Visual
Analysis:  Transfer the Sample to a suitable crucible. Ignite, gently at first, until free from carbon. Cool the crucible. Add 10 mL of water, and dissolve the residue by adding sufficient 3 N hydrochloric acid, dropwise, to achieve complete solution. Transfer the solution to a suitable container, and add about 150 mL of water. While stirring, preferably with a magnetic stirrer, add 20 mL of Titrant from a 50-mL buret. Add 15 mL of 1 N sodium hydroxide, then add the Indicator. Continue the titration to a blue endpoint. Perform a Blank determination.
Calculate the percentage of the labeled amount of calcium gluconate (C12H22CaO14) in the portion of Tablets taken:
Result = {[(VS VB) × M × F]/W} × 100
VS== Titrant volume consumed by the Sample (mL)
VB== Titrant volume consumed by the Blank (mL)
M== actual molarity of the Titrant (mM/mL)
F== equivalency factor, 430.4 (mg/mM)
W== nominal weight of calcium gluconate in the Sample (mg)
Acceptance criteria:  95.0%–105.0%
•  Dissolution 711
Medium:  Water; 900 mL
Apparatus 2:  50 rpm
Time:  45 min
Standard solution:  Solution having a known concentration of calcium in Medium
Sample solution:  Filtered portion of the solution under test, suitably diluted with Medium if necessary
Instrumental conditions 
Mode:  Atomic absorption spectrophotometry
Analytical wavelength:  422.8 nm
Lamp:  Calcium hollow-cathode
Flame:  Air–acetylene
Samples:  Standard solution and Sample solution
Calculate the percentage of the labeled amount of calcium gluconate (C12H22CaO14) dissolved:
Result = (AU/AS) × (CS × D × V/L) × (Mr/Ar) × 100
AU== absorbance of the Sample solution
AS== absorbance of the Standard solution
CS== concentration of calcium in the Standard solution (mg/mL)
D== dilution factor for the Sample solution
V== volume of Medium, 900 mL
L== label claim (mg/Tablet)
Mr== molecular weight of calcium gluconate, 430.4
Ar== atomic weight of calcium, 40.078
Tolerances:  NLT 75% (Q) of the labeled amount of calcium gluconate (C12H22CaO14) is dissolved.
•  Uniformity of Dosage Units 905: Meet the requirements
•  Packaging and Storage: Preserve in well-closed containers.
•  USP Reference Standards 11
USP Potassium Gluconate RS Click to View Structure
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Natalia Davydova
Scientific Liaison
(DS2010) Monographs - Dietary Supplements
711 Margareth R.C. Marques, Ph.D.
Senior Scientific Liaison
(GCDF2010) General Chapters - Dosage Forms
Reference Standards RS Technical Services
USP35–NF30 Page 2456
Pharmacopeial Forum: Volume No. 27(6) Page 3258