Polydextrose
[68424-04-4].
(pol'' ee dex' trose).
[68424-04-4].DEFINITION
Polydextrose is a randomly branched polymer prepared by melting and subsequent condensation of the ingredients, which consist of approximately 90 parts dextrose, 10 parts sorbitol, and up to 1 part citric acid or 0.1 part phosphoric acid. The 1,6-glycosidic linkage predominates in the polymer but other linkages are present. It contains NLT 90.0% of dextrose polymer units, calculated on the anhydrous and ash-free basis. It contains small quantities of free dextrose, sorbitol, and 1,6-anhydro-d-glucose (levoglucosan), with traces of citric acid or phosphoric acid.
IDENTIFICATION
• A.
To 1 drop of a solution (1 in 10), add 4 drops of 5% phenol solution, then rapidly add 15 drops of sulfuric acid TS: a deep yellow to orange color is produced.
• B.
With vigorous swirling, add 1 mL of acetone to 1 mL of a solution (1 in 10): the solution remains clear.
• C.
With vigorous swirling, add 2 mL of acetone to the solution obtained in Identification test B: a heavy, milky turbidity develops immediately.
• D.
To 1 mL of a solution (1 in 50), add 4 mL of alkaline cupric citrate TS. Boil vigorously for 2–4 min. Remove from heat, and allow the precipitate (if any) to settle: the supernatant is blue or blue-green.
ASSAY
• Procedure
Mobile phase:
0.001 N sulfuric acid. Pass this solution through a filter of 0.5-µm pore size, and degas.
Standard solution:
4.0 mg/mL of USP Polydextrose RS, calculated on the anhydrous and ash-free basis, in Mobile phase
Sample solution:
4.0 mg/mL of Polydextrose, calculated on the anhydrous and ash-free basis, in Mobile phase
Chromatographic system
Mode:
LC
Detector:
Refractive index
Detector temperature:
35 ± 0.1
Guard column:
4.6-mm × 3.0-cm, packing L17
Analytical column:
7.8-mm × 30-cm, packing L17
Flow rate:
0.6 mL/min
Injection size:
20 µL
System suitability
Sample:
Standard solution
Suitability requirements
Relative standard deviation:
NMT 2.0%
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of dextrose polymer units in the portion of Polydextrose taken:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = peak response of dextrose polymer units from the Sample solution |
| rS | = | = peak response of dextrose polymer units from the Standard solution |
| CS | = | = concentration of USP Polydextrose RS in the Standard solution (mg/mL) |
| CU | = | = concentration of Polydextrose in the Sample solution (mg/mL) |
Acceptance criteria:
NLT 90.0%
IMPURITIES
Inorganic Impurities
• Residue on Ignition 
281
:
NMT 0.3%
281:
NMT 0.3%
• Limit of Lead
[Note—Use reagent-grade chemicals with as low a lead content as is practicable, as well as high-purity water and gases. Before use in this analysis, rinse all glassware and plasticware twice with 10% nitric acid and twice with 10% hydrochloric acid, and then rinse them thoroughly with Purified Water. ]
Matrix modifier solution:
Prepare a solution in water containing 100.0 mg of dibasic ammonium phosphate per 10 mL of solution.
Lead nitrate stock solution:
Dissolve 159.8 mg of lead nitrate in 100 mL of water to which has been added 1 mL of nitric acid, then dilute with water to 1000 mL. Prepare and store this solution in glass containers free from soluble lead salts.
Standard lead solution:
On the day of use, dilute 10.0 mL of Lead nitrate stock solution with water to 100.0 mL. Each mL of Standard lead solution contains the equivalent of 10 µg of lead.
Standard solution A:
0.02 µg/mL of lead, from Standard lead solution in water
Standard solution B:
0.05 µg/mL of lead, from Standard lead solution in water
Standard solution C:
0.1 µg/mL of lead, from Standard lead solution in water
Standard solution D:
0.2 µg/mL of lead, from Standard lead solution in water
Standard solution E:
0.5 µg/mL of lead, from Standard lead solution in water
Sample solution:
Transfer 1.0 g of Polydextrose, weighed and calculated on the anhydrous and ash-free basis, into a 10-mL volumetric flask, and dissolve in and dilute with water to volume.
Spiked sample solution:
Transfer 1.0 g of Polydextrose, weighed and calculated on the anhydrous and ash-free basis, into a 10-mL volumetric flask, and dissolve in water. Add 100 µL of the Standard lead solution, and dilute with water to volume. This solution contains 0.1 µg/mL of added lead.
Spectrometric conditions
Mode:
Graphite furnace atomic absorption spectrophotometer, equipped with a pyrolytic tube with a platform
Lamp:
A lead hollow-cathode lamp, using a slit width of 0.7 mm (set low) and a deuterium arc lamp for background correction
Analytical wavelength:
Lead emission line of 283.3 nm
Autosampler
Sample volume:
10 µL
Alternative volume:
10 µL of Matrix modifier solution
Furnace program:
See the temperature program table below.
| Step | Dry | Char | Atomize | Clean | Recharge |
|---|---|---|---|---|---|
| Temperature ( ) |
130 | 800 | 2400 | 2600 | 20 |
| Ramp time (s) |
20 | 20 | 0 | 1 | 2 |
| Hold time (s) |
40 | 40 | 6 | 5 | 20 |
| Argon flow rate (mL/min) |
300 | 300 | 50 | 300 | 300 |
Analysis
Samples:
10 µL of the Matrix modifier solution was added into each 10-µL aliquot of the five Standards solutions, a mixture of 10 µL of the Matrix modifier solution and 10 µL of the Sample solution, and a mixture of 10 µL of the Matrix modifier solution and 10 µL of the Spiked sample solution
Concomitantly determine the absorbances of the Samples using the Spectrometric conditions described above. Plot the absorbance of each Standard solution, compensated for background correction, versus its content of lead, in µg/mL, and draw the best straight line fitting the five points. From this plot, determine the concentrations, CT and CST, in µg/mL, of lead in the Sample solution and the Spiked sample solution, respectively.
Calculate the percentage recovery taken:
Result = [(CST 
CT)/A] × 100
CT)/A] × 100| A | = | = quantity of lead added to the Spiked sample solution, 0.1 µg/mL |
Calculate the content, in µg/g, of lead in the portion of Polydextrose taken:
Result = (CT/W) × V
| W | = | = weight of Polydextrose taken to prepare the Sample solution (g) |
| V | = | = volume of the Sample solution, 10 mL |
Acceptance criteria:
NMT 0.5 µg/g. The recovery is 80%–120%.
Organic Impurities
• Procedure 1: Limit of 5-Hydroxymethylfurfural and Related Compounds
Sample solution:
1.0 g of Polydextrose, weighed and calculated on the anhydrous and ash-free basis, diluted with water to 100 mL
Analysis:
Determine the absorbance of the Sample solution in a 1-cm quartz cell at 283 nm, with a suitable spectrophotometer, using water as the blank.
Calculate the percentage of 5-hydroxymethylfurfural and related compounds in the Polydextrose taken:
Result = 100 × (V × Mr × A)/(M × L × W)
| V | = | = volume of the Sample solution, 0.1 L |
| Mr | = | = molecular weight of 5-hydroxymethylfurfural, 126 g/mol |
| A | = | = absorbance of the Sample solution |
| M | = | = molar extinction coefficient of 5-hydroxymethylfurfural at a wavelength of 283 nm, 16,830 L/mol cm |
| L | = | = path length of the spectrophotometer cell (cm) |
| W | = | = weight of Polydextrose taken to prepare the Sample solution (g) |
Acceptance criteria:
NMT 0.1%
• Procedure 2: Limit of Monomers
Mobile phase, Sample solution, and Chromatographic system:
Prepare as directed in the Assay.
Standard solution:
0.08 mg/mL of each of USP 1,6-Anhydro-d-glucose RS and USP Sorbitol RS, and 0.16 mg/mL of USP Dextrose RS, in Mobile phase
System suitability
Sample:
Standard solution
[Note—For relative retention times, see Table 1 below. ]
Table 1
| Name | Relative Retention Time |
|---|---|
| Dextrose (glucose) | 0.7 |
| Sorbitol | 0.8 |
| An isomer of 1,6-anhydro-d-glucose (d-anhydroglucose furanose form) | 0.9 |
| 1,6-Anhydro-d-glucose (d-anhydroglucose pyranose form) | 1.0 |
Suitability requirements
Resolution:
NLT 1.0
Relative standard derivation:
NMT 5.0%
Analysis
Samples:
Standard solution and Sample solution
Use peak response of USP 1,6-Anhydro-d-glucose RS in the Standard solution for calculation of percentage of the isomer of 1,6-anhydro-d-glucose in the Sample solution. Calculate the percentage of each monomer in the portion of Polydextrose taken:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = peak response of the respective monomer from the Sample solution |
| rS | = | = peak response of the respective monomer from the Standard solution |
| CS | = | = concentration of the respective standard monomer in the Standard solution (mg/mL) |
| CU | = | = concentration of Polydextrose in the Sample solution (mg/mL) |
Acceptance criteria:
NMT 4.0% for 1,6-anhydro-d-glucose, NMT 4.0% for dextrose, and NMT 2.0% for sorbitol. [Note—In the case of 1,6-anhydro-d-glucose, the peak areas for the pyranose and furanose forms are combined. ]
SPECIFIC TESTS
• Molecular Weight Limit
Mobile phase:
Dissolve 35.0 g of sodium nitrate and 1.0 g of sodium azide in 100 mL of water. Dilute with water to 4 L. Pass through a filter of 0.45-µm pore size, and degas by applying an aspirator vacuum for 30 min. The resulting Mobile phase is 0.1 N sodium nitrate containing 0.025% sodium azide.
Standard solution:
Transfer 20 mg each of USP Dextrose RS, stachyose, and 5800-, 23,700-, and 100,000-molecular weight (MW) pullulan standards into a 10-mL volumetric flask. Dissolve in and dilute with Mobile phase to volume. Pass through a syringe filter of 0.45-µm pore size into a suitable autosampler vial, and seal.
Sample solution:
Transfer 50 mg of Polydextrose into a 10-mL volumetric flask. Dissolve in and dilute with Mobile phase to volume. Pass through a syringe filter of 0.45-µm pore size into a suitable autosampler vial, and seal.
Chromatographic system
Mode:
LC
Detector:
Refractive index set at a sensitivity of 4 × 106 refractive index units full scale and maintained at a temperature of 35 ± 0.1
6 refractive index units full scale and maintained at a temperature of 35 ± 0.1
Column:
7.8-mm × 30-cm; packing L39
Column temperature:
45
Flow rate:
0.8 mL/min
[Note—After installation of a new column, pump Mobile phase through the column overnight at a rate of 0.3 mL/min. Before calibration or analysis, increase the flow slowly over a 1-min period to 0.8 mL/min. Continue to pump Mobile phase through the column at this flow rate for at least 1 h before the first injection. Check the flow gravimetrically, and adjust it if necessary. Reduce the flow rate to about 0.1 mL/min when the system is not in use. ]
Injection size:
50 µL
System suitability
Sample:
Standard solution
[Note—The retention times for each component determined on replicate injections agree within ±2 s. ]
Chromatograph five replicate injections of the Standard solution, allowing 15 min between injections, and record the retention times of the components of the Standard solution.
Insert the average retention time along with the molecular weight of each component in the Standard solution into the calibration table of the molecular weight distribution software. Check the regression results for a cubic fit of the calibration points, and obtain a correlation coefficient, R, for the line.
Suitability requirements
Resolution:
Dextrose and stachyose are baseline resolved from one another and from the 5800-MW pullulan standard.
[Note—Prominent negative baseline valleys are usually observed between the peaks for the 5800-; 23,700-; and 100,000-MW pullulan standards. ]
Correlation coefficient R:
NLT 0.9999
Analysis
Samples:
Standard solution and Sample solution
Use the molecular weight distribution software of the data reduction system to generate a molecular weight distribution plot of Polydextrose.
Acceptance criteria:
No measurable peak above a molecular weight of 22,000 is found.
• pH 791:
2.5–5.0, in a solution (1 in 10)
791:
2.5–5.0, in a solution (1 in 10)
• Water Determination, Method I 921:
NMT 4.0%. Use a mixture of Hydranal solvent and Hydranal formamide dry (2:1) as a solvent. Perform the titration at 50 in a jacketed beaker.
921:
NMT 4.0%. Use a mixture of Hydranal solvent and Hydranal formamide dry (2:1) as a solvent. Perform the titration at 50 in a jacketed beaker.
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight, light-resistant containers. Store in a cool and dry place.
• USP Reference Standards 11
11
USP 1,6-Anhydro-d-glucose RS 
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USP Dextrose RS
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USP Sorbitol RS
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Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Robert H. Lafaver, M.S.
Scientific Liaison 1-301-816-8335 |
(EXC2010) Monographs - Excipients |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 1896
Pharmacopeial Forum: Volume No. 35(5) Page 1206