Anhydrous Lactose
Legend: + will adopt and implement; will not stipulate.
Nonharmonized attributes: Characters, Labeling, Microbial limits, Heavy metals, Packaging and storage, Identification (IR).
Specific local attributes: Identification B and C (USP), Particle size distribution (USP), Particle size distribution EP (FRC).
» Anhydrous Lactose is O-
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Packaging and storage
Preserve in tight containers.
Labeling
Where the labeling indicates the relative quantities of alpha and beta lactose, determine compliance using Content of alpha and beta anomers. Where the labeling states the particle size distribution, it also indicates the d10, d50, and d90 values and the range for each.
USP Reference standards
![]() ![]() USP Anhydrous Lactose RS. USP Sucrose RS. USP Fructose RS. USP Dextrose RS.
Clarity and color of solution
A solution of 1 g in 10 mL of boiling water is clear and nearly colorless. Determine the absorbance of this solution at a wavelength of 400 nm. The absorbance divided by the path length, in cm, is not more than 0.04.
Identification
B:
Proceed as directed in Identification test B under Lactose Monohydrate, except to use USP Anhydrous Lactose RS instead of USP Lactose Monohydrate RS in Standard solution A and B and to use Anhydrous Lactose in the Test solution.
Specific rotation
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Microbial enumeration tests
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Acidity or alkalinity
Dissolve 6 g by heating in 25 mL of carbon dioxide-free water, cool, and add 0.3 mL of phenolphthalein TS: the solution is colorless, and not more than 0.4 mL of 0.1 N sodium hydroxide is required to produce a red color.
Loss on drying
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Water, Method I
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Residue on ignition
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Heavy metals, Method II
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Protein and light-absorbing impurities
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Content of alpha and beta anomers
Silylation reagent
Prepare a mixture of pyridine and trimethylsilylimidazole (72:28).
Resolution mixture
Prepare a mixture of alpha lactose monohydrate and beta lactose having an anomeric ratio of about 1:1 based on the labeled anomeric contents of the alpha lactose monohydrate and the beta lactose.
Chromatographic system
(see Chromatography
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Derivatization procedure
Transfer about 1 mg of Anhydrous Lactose to a 5-mL reaction vial equipped with a screw cap, add 0.45 mL of dimethyl sulfoxide, seal the vial tightly with a screw cap, and mix on a vortex mixer to dissolve. Add 1.8 mL of Silylation reagent, seal the vial tightly with a screw cap, and mix gently. Transfer about 1 mg of Resolution mixture to a second 5-mL reaction vial equipped with a screw cap, add 0.45 mL of dimethyl sulfoxide, seal the vial tightly with a screw cap, and mix on a vortex mixer to dissolve. Add 1.8 mL of Silylation reagent, seal the vial tightly with a screw cap, and mix gently. Maintain both vials at room temperature for 20 minutes before using.
Procedure
Inject a 2.0-µL portion of the derivatized Resolution mixture into the chromatograph, and record the peak areas for the major peaks: the relative retention times are about 0.7 for the silyl derivative of alpha lactose and 1.0 for the silyl derivative of beta lactose, and the resolution, R, between the two peaks is not less than 3.0. Similarly inject a 2.0-µL portion of the derivatized Anhydrous Lactose into the chromatograph, and record the peak areas for the major peaks. Determine the percentage of alpha anomer in the Anhydrous Lactose by the formula:
100ra / (ra + rb)
in which ra is the response of the alpha anomer silyl derivative peak and rb is the response of the beta anomer silyl derivative peak. Determine the percentage of beta anomer in the Anhydrous Lactose by the formula:
100rb / (ra + rb)
in which the terms are as defined above.
Auxiliary Information
Please check for your question in the FAQs before contacting USP.
Chromatographic Column
USP32NF27 Page 1263
Pharmacopeial Forum: Volume No. 32(6) Page 1847
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.
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