Calcium Lactobionate
(kal' see um lak'' toe bye' oh nate).
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C24H42CaO24·2H2O 790.68
d-Gluconic acid, 4-O--d-galactopyranosyl-, calcium salt (2:1), dihydrate;    
Lactobionic acid, calcium salt (2:1), dihydrate;    
Calcium lactobionate (1:2), dihydrate     [110638-68-1].
Calcium Lactobionate contains NLT 96.0% and NMT 102.0% of calcium lactobionate (C24H42CaO24·2H2O).
•  A. Identification Tests—General, Calcium 191: A 20 mg/mL solution meets the requirements.
•  C. Thin Layer Chromatography
Standard solution:  10 mg/mL of USP Calcium Lactobionate RS in water
Sample solution:  10 mg/mL of Calcium Lactobionate in water
Chromatographic system 
Mode:  TLC
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, dilute with 2 N sulfuric acid to volume, and mix.
Samples:  Standard solution and Sample solution
Develop the chromatogram until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the chamber, and dry at 100 for 20 min. Allow to cool, and spray with the 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:  800 mg of Calcium Lactobionate
Blank:  150 mL of water and 2 mL of 3 N hydrochloric acid
Titrimetric system 
Mode:  Direct titration
Titrant:  0.05 M edetate disodium VS
Endpoint detection:  Visual
Analysis:  Dissolve the Sample in a mixture of water and 3 N hydrochloric acid (150:2). While stirring with a magnetic stirrer, add 15 mL of Titrant from the titration buret. Add 15 mL of 1 N sodium hydroxide and 300 mg of hydroxy naphthol blue, and continue the titration to a blue endpoint. Perform the Blank determination.
Calculate the percentage of calcium lactobionate (C24H42CaO24·2H2O) in the Sample 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== Titrant molarity (mM/mL)
F== equivalency factor, 790.7 mg/mmol
W== Sample weight (mg)
Acceptance criteria:  96.0%–102.0%
•  Halides
Standard solution:  0.7 mL of 0.020 N hydrochloric acid
Sample:  1.2 g
Analysis:  Proceed as directed for Chloride and Sulfate 221, Chloride.
Acceptance criteria:  NMT 0.04%
•  Chloride and Sulfate, Sulfate 221
Standard solution:  1 mL of 0.020 N sulfuric acid
Sample:  2.0 g
Analysis:  Dissolve the Sample in boiling water.
Acceptance criteria:  NMT 0.05%
•  Heavy Metals 231
Test preparation:  Mix 1 g in 4 mL of 1.2 N hydrochloric acid. Add water to make 25 mL, warm gently until dissolved, and cool to room temperature.
Acceptance criteria:  NMT 20 ppm
•  Reducing Substances
Sample:  1.0 g of Calcium Lactobionate
Blank:  20 mL of water
Titrimetric system 
Mode:  Residual titration
Titrant:  0.1 N iodine VS
Back-titrant:  0.1 N sodium thiosulfate VS
Endpoint detection:  Visual
Analysis:  Transfer the Sample to a 250-mL conical flask, dissolve in the Blank, and add 25 mL of alkaline cupric citrate TS. Cover the flask, boil gently for 5 min, accurately timed, and cool rapidly to room temperature. Add 25 mL of 0.6 N acetic acid, 10.0 mL of Titrant, and 10 mL of 3 N hydrochloric acid, and titrate with Back-titrant, adding 3 mL of starch TS as the endpoint is approached. Perform the Blank determination.
Calculate the percentage of reducing substances (as dextrose) in the Sample taken:
Result = {[(VB VS) × N × F]/W} × 100
VB== Back-titrant volume consumed by the Blank (mL)
VS== Back-titrant volume consumed by the Sample (mL)
N== Back-titrant normality (mEq/mL)
F== equivalency factor, 27 mg/mEq
W== Sample weight (mg)
Acceptance criteria:  NMT 1.0%
•  Optical Rotation, Specific Rotation 781S
Sample solution:  100 mg/mL
Acceptance criteria:  +22.0 to +26.5
•  pH 791
Sample solution:  50 mg/mL
Acceptance criteria:  5.4–7.4
•  Packaging and Storage: Preserve in well-closed containers.
•  USP Reference Standards 11
USP Calcium Lactobionate RS Click to View Structure
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Huy T. Dinh, M.S.
Scientific Liaison
(DS2010) Monographs - Dietary Supplements
Reference Standards RS Technical Services
USP35–NF30 Page 2459
Pharmacopeial Forum: Volume No. 27(6) Page 3260