Inositol
Click to View Image
C6H12 O6 180.2

cis-1,2,3,5-trans-4,6-Cyclohexanehexol.

myo-Inositol [87-89-8].
» Inositol contains not less than 97.0 percent and not more than 102.0 percent of C6H12O6, calculated on the anhydrous basis.
Packaging and storage— Preserve in well-closed containers, and store at room temperature.
Clarity of solution— [note—The Test solution is to be compared to Reference suspension A in diffused daylight 5 minutes after preparation of Reference suspension A.]
Test solution— Dissolve 10.0 g of Inositol in about 50 mL of water, dilute with water to 100 mL, and mix.
Hydrazine sulfate solution— Transfer 1.0 g of hydrazine sulfate to a 100-mL volumetric flask, dissolve in and dilute with water to volume, and mix. Allow to stand for 4 to 6 hours before use.
Methenamine solution— Transfer 2.5 g of methenamine to a 100-mL glass-stoppered flask, add 25.0 mL of water, insert the glass stopper, and mix to dissolve.
Primary opalescent suspension— [note—This suspension is stable for 2 months, provided it is stored in a glass container free from surface defects. The suspension must not adhere to the glass and must be well mixed before use.] Transfer 25.0 mL of Hydrazine sulfate solution to the Methenamine solution in the 100-mL glass-stoppered flask, and mix. Allow to stand for 24 hours.
Opalescence standard— [note—This suspension should not be used beyond 24 hours after preparation.] Transfer 15.0 mL of the Primary opalescent suspension to a 1000-mL volumetric flask, dilute with water to volume, and mix.
Reference suspensions— Transfer 5.0 mL of the Opalescence standard to a 100-mL volumetric flask, dilute with water to volume, and mix to obtain Reference suspension A. Transfer 10.0 mL of the Opalescence standard to a second 100-mL volumetric flask, dilute with water to volume, and mix to obtain Reference suspension B.
Procedure— Transfer a sufficient portion of the Test solution to a test tube of colorless, transparent, neutral glass, with a flat base and an internal diameter of 15 to 25 mm, to obtain a depth of 40 mm. Similarly transfer portions of Reference suspension A, Reference suspension B, and water to separate matching test tubes. Compare the Test solution, Reference suspension A, Reference suspension B, and water in diffused daylight, viewing vertically against a black background (see Visual Comparison under Spectrophotometry and Light-Scattering 851). [note—The diffusion of light must be such that Reference suspension A can readily be distinguished from water, and that Reference suspension B can readily be distinguished from Reference suspension A.] The Test solution shows the same clarity as that of water.
Color of solution—
Standard stock solutions— Prepare three solutions, A, B, and C, containing, respectively, the following parts of ferric chloride CS, cobaltous chloride CS, cupric sulfate CS, and diluted hydrochloric acid:
Standard stock solution A: 2.4:0.6:0:7.0
Standard stock solution B: 2.4:1.0:0.4:6.2
Standard stock solution C: 9.6:0.2:0.2:0
Standard solutions— [note—Prepare the Standard solutions immediately before use.] Transfer 2.5 mL of Standard stock solution A to a 100-mL volumetric flask, dilute with diluted hydrochloric acid to volume, and mix to obtain Standard solution A. Transfer 2.5 mL of Standard stock solution B to a 100-mL volumetric flask, dilute with diluted hydrochloric acid to volume, and mix to obtain Standard solution B. Transfer 0.75 mL of Standard stock solution C to a 100-mL volumetric flask, dilute with diluted hydrochloric acid to volume, and mix to obtain Standard solution C.
Test solution— Use the Test solution prepared in the test for Clarity of solution.
Procedure— Transfer a sufficient portion of the Test solution to a test tube of colorless, transparent, neutral glass, with a flat base and an internal diameter of 15 to 25 mm, to obtain a depth of 40 mm. Similarly transfer portions of Standard solution A, Standard solution B, Standard solution C, and water to separate matching test tubes. Compare the Test solution, Standard solution A, Standard solution B, Standard solution C, and water in diffused daylight, viewing vertically against a white background (see Visual Comparison under Spectrophotometry and Light-Scattering 851). The Test solution is not more intensely colored than Standard solution A, Standard solution B, Standard solution C, or water.
Identification—
B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.
Conductivity—
Test solution— Transfer about 10.0 g of Inositol, accurately weighed and calculated on the dried basis, to a 50-mL volumetric flask, dissolve in and dilute with water (previously boiled and cooled to room temperature) to volume, and mix.
Apparatus— Use a conductivity meter or a resistivity meter that measures the resistance of the column of liquid between the electrodes of the immersed measuring device. The apparatus is supplied with alternating current to avoid the effects of electrode polarization. It is equipped with a temperature compensation device or a precision thermometer.
Reagents— Prepare three standard solutions of potassium chloride containing 0.7455 g, 0.0746 g, and 0.0149 g, respectively, of potassium chloride per 1000.0 g of solution. These solutions should be prepared with water that has been previously boiled and cooled to room temperature and whose conductivity does not exceed 2 µS per cm. The conductivity and resistivity of these three solutions at 20 are given in the table below.
Concentration of Solution
(g/1000.0 g)
Conductivity
(µS per cm)
Resistivity
(W-cm)
0.7455 1330 752
0.0746 133.0 7519
0.0149 26.6 37,594
Calibration— Choose a conductivity cell that is appropriate for the conductivity of the solution to be examined. The higher the expected conductivity, the higher the cell constant that must be chosen. Commonly used conductivity cells have cell constants of the order 0.1 cm1, 1 cm1, and 10 cm1. Use a standard solution of potassium chloride that is appropriate for the measurement. The conductivity value of the standard solution of potassium chloride should be near the expected conductivity value of the Test solution. Rinse the cell several times with water that has been previously boiled and cooled to room temperature, and at least twice with the potassium chloride solution used for the determination of the cell constant of the conductivity cell. Measure the resistance of the conductivity cell, using the potassium chloride solution at 20 ± 0.1. The constant C (in cm1) of the conductivity cell is given by the expression:
C = RKCl × KKCl
where RKCl is the measured resistance, expressed in mega-ohms; and KKCl is the conductivity of the standard solution of potassium chloride used, expressed in µS per cm. The measured constant, C, of the conductivity cell must be within 5% of the given value.
Procedure— Rinse the conductivity cell several times with water that has been previously boiled and cooled to room temperature, and at least twice with the Test solution. Measure the conductivity of the Test solution, while gently stirring with a magnetic stirrer: the conductivity is not more than 20 µS per cm.
Water, Method I 921: not more than 0.5% determined on a 1.0 g sample.
Barium—
Test solution— Use the Test solution prepared in the test for Clarity of solution. To 10 mL of Test solution add 1 mL of diluted sulfuric acid. When examined immediately and after 1 h, any opalescence in the solution is not more intense than that in a mixture of 1 mL of water and 10 mL of the Test solution prepared in the test for Clarity of solution.
Limit of lead—
Standard lead solution— Prepare as directed for Standard Lead Solution in Special Reagents under Heavy Metals 231.
Test solution— Dissolve 20.0 g of Inositol in diluted acetic acid, and dilute with diluted acetic acid to 100 mL. Add 2.0 mL of a saturated ammonium pyrrolidinedithiocarbamate solution (containing about 10 g of ammonium pyrrolidinedithiocarbamate per L) and 10.0 mL of methyl isobutyl ketone, and shake for 30 seconds. Protect from bright light. Allow the two layers to separate, and use the methyl isobutyl ketone layer.
Blank solution— Prepare as directed for Test solution, except to omit the use of Inositol.
Standard solutions— Prepare as directed for Test solution, except to prepare three standard solutions by adding 0.5 mL, 1.0 mL, and 1.5 mL, respectively, of Standard lead solution in addition to the 20.0 g of Inositol to be examined.
Procedure— Set the atomic absorption spectrophotometer to zero, using methyl isobutyl ketone previously treated as described under Test solution, but without sample added. Use a lead hollow-cathode lamp as the source of radiation, an air–acetylene flame, and an analysis wavelength of 283.3 nm. Introduce the Test solution and each of the three Standard solutions into the instrument, and record the steady absorbance reading. Plot the absorbance readings against the known concentrations of added lead (in µg), and draw a straight line. Extrapolate the line until it meets the concentration axis to obtain the concentration, in mg per kg, of lead in the sample. Not more than 0.5 mg per kg is found.
Related compounds—
Mobile phase, System suitability solution, and Chromatographic system— Proceed as directed in the Assay.
Test solution— Use the Assay preparation.
Standard solution— Transfer 2.0 mL of the Standard preparation, prepared as directed in the Assay, to a 100-mL volumetric flask, dilute with water to volume, and mix. This solution contains about 1 mg of inositol per mL.
Procedure— Separately inject equal volumes (about 20 µL) of the Test solution and the Standard solution into the chromatograph, record the chromatograms, and measure the peak responses. Calculate the percentage of each impurity found by the formula:
VC / W(ri / rS)
in which V is the volume, in mL, of the Test solution; C is the concentration, in mg per mL, of inositol in the Standard solution; W is the quantity, in mg, of inositol taken to prepare the Test solution; ri is the peak response of any impurity obtained from the Test solution; and rS is the response of the inositol peak obtained from the Standard solution: not more than 0.3% of any individual impurity is found, and not more than 1.0% of total impurities is found. Disregard any impurity peak that is less than 0.05%.
Assay—
Mobile phase— Use degassed water.
Standard preparation— Dissolve an accurately weighed quantity of USP Inositol RS in water to obtain a solution having a known concentration of about 50 mg per mL.
Assay preparation— Transfer about 500 mg of Inositol, accurately weighed, to a 10-mL volumetric flask, dissolve in and dilute with water to volume, and mix.
System suitability solution— Transfer accurately weighed quantities of USP Inositol RS and USP Mannitol RS to a suitable volumetric flask, and dissolve in and dilute with water to obtain a solution having known concentrations of about 0.05 mg of each per mL.
Chromatographic system (see Chromatography 621) The liquid chromatograph is equipped with a refractive index detector maintained at a constant temperature of about 30 to 35 and a 7.8-mm × 30-cm column or equivalent that contains packing L19. The column temperature is maintained at 85. The flow rate is about 0.5 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the relative retention times are about 1.0 for inositol and 1.3 for mannitol; and the resolution, R, between inositol and mannitol is not less than 4.0. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 2.0%.
Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms over a period of two times the retention time of inositol, and measure the peak responses. Calculate the quantity, in mg, of C6H12O6 in the portion of Inositol taken by the formula:
VC(rU / rS)
in which V is the volume, in mL, of the Assay preparation; C is the concentration, in mg per mL, of USP Inositol RS in the Standard preparation; and rU and rS are the peak responses for inositol obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Robert H. Lafaver, B.A.
Scientist
1-301-816-8335
(EM105) Excipient Monographs 1
Reference Standards Lili Wang, Technical Services Scientist
1-301-816-8129
RSTech@usp.org
USP32–NF27 Page 1258
Pharmacopeial Forum: Volume No. 33(4) Page 711
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.