Lactose Monohydrate
Heavy Metals 
231
(lak' tose mon'' oh hye' drate).
Portions of the monograph text that are national USP text, and are not part of the harmonized text, are marked with symbols () to specify this fact.
) to specify this fact.DEFINITION
Lactose Monohydrate is the monohydrate of O-
-d-galactopyranosyl-(1®4)-
-d-glucopyranose. [Note—Lactose Monohydrate may be modified as to its physical characteristics. It may contain varying proportions of amorphous lactose. ]
-d-galactopyranosyl-(1®4)--d-glucopyranose. [Note—Lactose Monohydrate may be modified as to its physical characteristics. It may contain varying proportions of amorphous lactose. ]
IDENTIFICATION
• B. Thin-Layer Chromatographic Identification Test 201
B. Thin-Layer Chromatographic Identification Test 201
Diluent:
Methanol and water (3:2)
Standard solution A:
0.5 mg/mL of USP Lactose Monohydrate RS in Diluent
Standard solution B:
0.5 mg/mL each of USP Dextrose RS, USP Lactose Monohydrate RS, USP Fructose RS, and USP Sucrose RS in Diluent
Sample solution:
0.5 mg/mL of Lactose Monohydrate in Diluent
Adsorbent:
0.25-mm layer of chromatographic silica gel
Application volume:
2 µL
Developing solvent system:
Ethylene dichloride, glacial acetic acid, methanol, and water (10:5:3:2)
Spray reagent:
5 mg/mL of thymol in a mixture of alcohol and sulfuric acid (19:1)
Analysis
Samples:
Standard solution A, Standard solution B, and Sample solution
Allow the spots to dry, and develop the plate in a paper-lined chromatographic chamber equilibrated with Developing solvent system for about 1 h prior to use. Allow the chromatogram to develop until the solvent front has moved about three-quarters of the length of the plate. Remove the plate from the chamber, dry in a current of warm air, and redevelop the plate in fresh Developing solvent system. Remove the plate from the chamber, mark the solvent front, and dry the plate in a current of warm air. Spray the plate evenly with Spray reagent. Heat the plate at 130
for 10 min.
for 10 min.
System suitability:
The test is not valid unless the chromatogram of Standard solution B shows four clearly discernible spots, disregarding any spots at the origin.
Acceptance criteria:
The principal spot from the Sample solution corresponds in appearance and RF value to that from Standard solution A.
IMPURITIES
• Residue on Ignition 281
281
Analysis:
A sample ignited at a temperature of 600 ± 50
Acceptance criteria:
NMT 0.1%
Delete the following:
Heavy Metals 231
Sample solution:
Acceptance criteria:
(Official 1-Dec-2015)
SPECIFIC TESTS
• Clarity and Color of Solution
Sample solution:
1 g in 10 mL of boiling water
Analysis:
The Sample solution is clear and nearly colorless. Determine the absorbance of this solution at a wavelength of 400 nm.
Acceptance criteria:
The absorbance divided by the path length, in cm, is NMT 0.04.
• Microbial Enumeration Tests 61 and Tests for Specified Microorganisms 62:
The total aerobic microbial count does not exceed 1 × 102 cfu/g, the total combined molds and yeasts count does not exceed 5 × 101 cfu/g, and it meets the requirements of the test for absence of Escherichia coli.
Microbial Enumeration Tests 61 and Tests for Specified Microorganisms 62:
The total aerobic microbial count does not exceed 1 × 102 cfu/g, the total combined molds and yeasts count does not exceed 5 × 101 cfu/g, and it meets the requirements of the test for absence of Escherichia coli.
• Optical Rotation, Specific Rotation 781S
781S
Sample solution:
Dissolve 10 g by heating in 80 mL of water to 50. Allow to cool, and add 0.2 mL of 6 N ammonium hydroxide. Allow to stand for 30 min, and dilute with water to 100 mL.
. Allow to cool, and add 0.2 mL of 6 N ammonium hydroxide. Allow to stand for 30 min, and dilute with water to 100 mL.
Acceptance criteria:
+54.4 to +55.9, calculated on the anhydrous basis, determined at 20
to +55.9, calculated on the anhydrous basis, determined at 20
• Acidity or Alkalinity
Sample solution:
Dissolve 6 g by heating in 25 mL of carbon dioxide-free water, cool, and add 0.3 mL of phenolphthalein TS.
Acceptance criteria:
The solution is colorless, and NMT 0.4 mL of 0.1 N sodium hydroxide VS is required to produce a pink or red color.
• Loss on Drying 731
Loss on Drying 731
Analysis:
Dry a sample at 80 for 2 h.
for 2 h.
Acceptance criteria
Monohydrate:
NMT 0.5%
Monohydrate, modified:
NMT 1.0%
• Water Determination, Method I 921
921
Sample solution:
Prepare a preparation containing Lactose Monohydrate in a mixture of methanol and formamide (2:1).
Acceptance criteria:
4.5%–5.5%
• Protein and Light-Absorbing Impurities
Sample solution:
1% (w/v)
Analysis:
Measure the light absorption of the Sample solution in the range of 210–300 nm.
Acceptance criteria:
The absorbance divided by the path length, in cm, is NMT 0.25 in the range of 210–220 nm and is NMT 0.07 in the range of 270–300 nm.
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight containers.
Packaging and Storage:
Preserve in tight containers.
• Labeling:
Where the labeling states the particle size distribution, it also indicates the d10, d50, and d90 values and the range for each. For modified Lactose Monohydrate, also label it to indicate the method of modification.
• USP Reference Standards 11
11
USP Dextrose RS 
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USP Fructose RS
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USP Lactose Monohydrate RS
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USP Sucrose RS
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Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Kevin T. Moore, Ph.D.
Manager, Pharmacopeial Harmonization (301) 816-8369 |
(EXC2010) Monographs - Excipients |
| 61 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison (301) 816-8339 |
(GCM2010) General Chapters - Microbiology |
| 62 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison (301) 816-8339 |
(GCM2010) General Chapters - Microbiology |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP38–NF33 Page 6721