Dextran 1

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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1 DEFINITION 

Dextran 1 is a low molecular weight fraction of dextran, consisting of a mixture of isomaltooligosaccharides. It is obtained by controlled hydrolysis and fractionation of dextrans produced by fermentation of Leuconostoc mesenteroides (strain NRRL B-512; CIP 78.59, or its sub strains, for example L. mesenteroides B-512F; NCTC, 10817), in the presence of sucrose. It is a Glucose polymer in which the linkages between glucose units are almost exclusively α-1,6. Its weight-average molecular weight is about 1000. 

2 IDENTIFICATION 

Change to read: 

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K (CN 1-May-2020) : To 1–2 mg each of USP Dextran 1 RS and the sample, add 1–2 drops of water, grind in an agate mortar for 1–2 min, add 300 mg of potassium bromide, and mix to a slurry. [Note—Do not grind.] Dry under vacuum at 40° for 15 min, and if it is not dry, continue drying for another 15 min. Crush the residue, prepare a disk, and run the IR spectrum with a blank potassium bromide disk in the reference beam. 

B. It meets the requirements of the test for Molecular Weight Distribution and Average Molecular Weight. 

3 IMPURITIES 

3.1 Limit of Sodium Chloride Sample: 5 g 

Titrimetric system (See Titrimetry 〈541〉.) Mode: Direct titration 

Titrant: 0.1 N silver nitrate VS 

Endpoint detection: Visual 

Analysis: Dissolve the Sample in 100 mL of water. Add 0.2 mL of potassium chromate TS, and titrate with Titrant. Each mL of Titrant is equivalent to 5.844 mg of sodium chloride. 

Acceptance criteria: NMT 1.5% 

3.2 Limit of Nitrogenous Impurities

(where it is labeled as intended for use in the preparation of injectables) (See Nitrogen Determination 〈461〉.) 

Sulfate solution: To 1000 mL of sulfuric acid add 5 g of anhydrous cupric sulfate and 500 g of potassium sulfate. Dissolve by heating, and store at 60°. [Note—If storage at 60° is not possible, prepare a smaller quantity of Sulfate solution on the day of use, adjusting proportions accordingly.] 

Indicator: Dilute a mixture of 20 mL of a 0.1% solution of bromocresol green in alcohol and 4 mL of methyl red TS with water to 100 mL. Sample solution: Transfer 0.2 g of Dextran 1, accurately weighed, to a micro-Kjeldahl ask. Add 4 mL of Sulfate solution. Analysis 

Sample: Sample solution 

Heat the Sample solution until the solution exhibits a clear green color and the sides of the ask are free from carbonaceous material. Cool, cautiously add 30 mL of water, and transfer the solution to a steam distillation unit. Rinse the Kjeldahl ask with three 5-mL portions of water, adding the washings to the solution. Add 15 mL of 45% sodium hydroxide solution, immediately close the distillation apparatus, and commence steam distillation without delay. Receive the distillate in 1 mL of Indicator and sucient water to cover the end of the condensing tube. Upon completion of the distillation, remove the receiving ask, and rinse the end of the condensing tube with a small quantity of water, adding the rinse to the distillate. Titrate the distillate with 0.010 N hydrochloric acid until the color changes from blue to reddish violet. Perform a blank determination, and make any necessary correction. 

Acceptance criteria: The corrected volume of 0.010 N hydrochloric acid required to change the color does not exceed 0.15 mL (110 ppm of nitrogen). 

3.3 Limit of Alcohol and Related Impurities 

Standard solution: To 25.0 mL of the Sample solution add 0.5 mL of a 2.5% (w/v) solution of n-propyl alcohol. Sample solution: Dissolve without heating 5.0 g of Dextran 1 in 100 mL of water, and distill the solution, collecting the rst 45 mL of the distillate. Dilute the distillate with water to 50.0 mL, and mix. 

Chromatographic system 

Mode: GC 

Detector: Flame ionization 

Column: 2-mm × 1.8-m; packed with S3 

Temperatures 

Column: 160° 

Injection port: 240° 

Detector: 210° 

Carrier gas: Nitrogen 

Flow rate: 25 mL/min. [Note—Injector seals may deteriorate after multiple injections of the Standard solution and Sample solution. Inspect the seals before making a series of injections.] 

Injection volume: 1 µL 

Analysis 

Samples: Standard solution, Sample solution, and a 0.05% (w/v) solution of n-propyl alcohol and water 

Acceptance criteria: After corrections for any impurities in the n-propyl alcohol solution and water, the total area of peaks from impurities in the Sample solution does not exceed the area of the n-propyl alcohol solution peak. 

4 SPECIFIC TESTS 

4.1 Ultraviolet-Visible Spectroscopy 〈857〉 

Sample solution: 15% 

Instrumental conditions 

Mode: UV 

Analytical wavelength: 375 nm 

Blank: Water 

Acceptance criteria: NMT 0.12 

4.2 Optical Rotation, Specific Rotation〈781S〉 

Sample solution: A solution in water at 20°, on the dried basis (dried at 70° under vacuum to constant weight), corrected for sodium chloride content 

Acceptance criteria: +148° to +164° 

4.3 Microbial Enumeration Tests 〈61〉and Tests for Specified Microorganisms 〈62〉:

The total aerobic microbial count does not exceed 102 cfu/g, determined by plate-count, and the total combined molds and yeasts count does not exceed 10 cfu/g. 

4.4 pH 〈791〉 

Sample solution: A 15% solution in water 

Acceptance criteria: 4.5–7.0 

4.5 Loss on Drying 〈731〉 

Analysis: Dry at 100°–105° for 5 h. 

Acceptance criteria: NMT 5.0% 

4.6 Bacterial Endotoxins Test 〈85〉

(where it is labeled as intended for use in the preparation of injectables): NMT 25.0 USP Endotoxin Units/g 

4.7 Molecular Weight Distribution and Average Molecular Weight 

Mobile phase: 2.9 mg/mL of sodium chloride, ltered and degassed 

Calibration solution: 0.45 mg of isomaltotriose (3 glucose units) and 0.60 mg of sodium chloride per mL 

Standard solution: 6.0–6.5 mg/mL of USP Dextran 1 RS in Mobile phase 

Sample solution: 6.0–6.5 mg/mL solution of Dextran 1 in Mobile phase 

Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: LC 

Detector: Differential refractive index 

Column: Two 10-mm × 30-cm columns in series; packing L54 

Column temperature: 20°–25° 

Flow rate: 0.07–0.08 mL/min, maintained constant to ±1% 

Injection volume: 100 µL 

System suitability 

Sample: Standard solution 

Suitability requirements: The M and the amounts of the fractions obtained for the Standard solution are within the values stated in the w 

data sheet that accompanies USP Dextran 1 RS. 

Analysis 

Samples: Calibration solution and Sample solution 

Using the retention times in the chromatogram of the Calibration solution, identify the peaks due to isomaltotriose and sodium chloride in the chromatograms of the Standard solution and the Sample solution. Disregard the peak due to sodium chloride in the Standard solution and the Sample solution. 

Calculate the weight-average molecular weight, M_W : 

Result = ΣW_iM_i

W_i = weight proportion of oligosaccharide i 

M_i = molecular weight of oligosaccharide i 

Use the molecular weight values for calculation from Table 1. 

Table 1 

Calculate the amounts of the fractions with fewer than 3 and with more than 9 glucose units for the Standard solution and the Sample solution. 

Acceptance criteria: The M_W of Dextran 1 is 850–1150. The fraction with fewer than 3 units of glucose is less than 15%, and the fraction with more than 9 units of glucose is less than 20%. 

5 ADDITIONAL REQUIREMENTS 

Packaging and Storage: Store in well-closed containers at a temperature between 4° and 30°. 

Labeling: Where it is intended for use in preparing injectable dosage forms, the label states that it is sterile or must be subjected to further processing during the preparation of injectable dosage forms. 

USP Reference Standards 〈11〉 

USP Dextran 1 RS