NF 31 Official Monographs / Polyethylene 2139 System suitability of 0.3 mL/min. Before calibration or analysis, increase Sample: Standard solution the flow slowly over a 1-min period to 0.8 mL/min. [NOTEÐSee the relative retention times table below.] Continue to pump Mobile phase through the column at this flow rate for at least 1 h before the first Relative injection. Check the flow gravimetrically, and adjust it Retention if necessary. Reduce the flow rate to about 0.1 mL/ Name Time min when the system is not in use.] Injection size: 50 µL Dextrose (glucose) 0.7 System suitability Sorbitol 0.8 Sample: Standard solution An isomer of 1,6-anhydro-D-glucose Chromatograph five replicate injections of the Standard (D-anhydroglucose furanose form) 0.9 solution, allowing 15 min between injections, and 1,6-Anhydro-D-glucose (levoglucosan) record the retention times of the components of the (D-anhydroglucose pyranose form) 1.0 Standard solution. Insert the average retention time along with the Suitability requirements molecular weight of each component in the Standard Resolution: NLT 1.0 solution into the calibration table of the molecular Relative standard derivation: NMT 5.0% weight distribution software. Check the regression Analysis results for a cubic fit of the calibration points, and Samples: Standard solution and Sample solution obtain a correlation coefficient, R, for the line. Use the peak response of USP 1,6-Anhydro-D-glucose Suitability requirements RS in the Standard solution for calculation of the Retention time: The retention times for each percentage of the isomer of 1,6-anhydro-D-glucose in component determined on replicate injections agree the Sample solution. Calculate the percentage of each within ±2 s. monomer in the portion of Hydrogenated Resolution: Dextrose and stachyose are baseline Polydextrose taken: resolved from one another and from the 5800-MW pullulan standard. Result = (rU/rS) × (CS/CU) × 100 [NOTEÐProminent negative baseline valleys are usually observed between the peaks for the 5800-, 23,700-, rU = peak response for the respective monomer and 100,000-MW pullulan standards.] from the Sample solution Correlation coefficient R: NLT 0.9999 rS = peak response for the respective monomer Analysis from the Standard solution Samples: Standard solution and Sample solution CS = concentration of the respective standard Use the molecular weight distribution software of the monomer in the Standard solution (mg/mL) data reduction system to generate a molecular weight CU = concentration of Hydrogenated Polydextrose distribution plot of Hydrogenated Polydextrose. in the Sample solution (mg/mL) Acceptance criteria: No measurable peak above a Acceptance criteria: NMT 4.0% of 1,6-anhydro-D- molecular weight of 22,000 is found. glucose, NMT 5.75% for sorbitol and NMT 0.25% for • PH 〈791〉: 5.0±7.0, in a solution (1 in 10) dextrose • WATER DETERMINATION, Method I 〈921〉: NMT 4.0%. Use a [NOTEÐIn the case of 1,6-anhydro-D-glucose, the peak mixture of Hydranal Solvent and Hydranal Formamide areas for the pyranose and furanose forms are dry (2:1) as a solvent. Perform the titration at 50° in a combined.] jacketed beaker. SPECIFIC TESTS ADDITIONAL REQUIREMENTS • MOLECULAR WEIGHT LIMIT • PACKAGING AND STORAGE: Preserve in tight, light-resistant Mobile phase: Dissolve 35.0 g of sodium nitrate and containers. Store in a cool and dry place. 1.0 g of sodium azide in 100 mL of water. Dilute with • USP REFERENCE STANDARDS 〈11〉 water to 4 L. Pass through a filter of 0.45-µm or finer USP 1,6-Anhydro-D-glucose RS pore size, and degas by applying an aspirator vacuum USP Dextrose RS for 30 min. The resulting Mobile phase is 0.1 N sodium USP Polydextrose RS nitrate containing 0.025% sodium azide. USP Sorbitol RS 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 or finer pore size into a suitable autosampler Polyethylene Glycol vial, and seal. Sample solution: Transfer 50 mg of Hydrogenated 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 or finer pore size into a Poly(oxy-1,2-ethanediyl), α-hydro-ω-hydroxy-; suitable autosampler vial, and seal. Polyethylene glycol [25322-68-3]. Chromatographic system (See Chromatography 〈621〉, System Suitability.) DEFINITION Mode: LC Polyethylene Glycol is an addition polymer of ethylene oxide Detector: Refractive index set at a sensitivity of and water, represented: 4 × 10−6 refractive index units full scale and maintained H(OCH2CH2)nOH at a temperature of 35 ± 0.1° Column: 7.8-mm × 30-cm; packing L39 in which n represents the average number of oxyethylene Column temperature: 45° groups. The average molecular weight is NLT 95.0% and Flow rate: 0.8 mL/min NMT 105.0% of the labeled nominal value if the labeled [NOTEÐAfter installation of a new column, pump nominal value is less than 1000; it is NLT 90.0% and Mobile phase through the column overnight at a rate NMT 110.0% of the labeled nominal value if the labeled 2140 Polyethylene / Official Monographs NF 31 nominal value is between 1000 and 7000; and it is NLT Accceptance criteria: NMT 0.1% 87.5% and NMT 112.5% of the labeled nominal value if • HEAVY METALS 〈231〉 the labeled nominal value is more than 7000. It may con- Test preparation: 4.0 g in 5.0 mL of 0.1 N hydrochloric tain a suitable antioxidant. acid. Dilute with water to 25 mL. Acceptance criteria: NMT 5 ppm ASSAY • LIMIT OF FREE ETHYLENE OXIDE AND 1,4-DIOXANE • AVERAGE MOLECULAR WEIGHT Stripped polyethylene glycol 400: Into a 5000-mL, Phthalic anhydride solution: Place 49.0 g of phthalic 3-neck, round-bottom flask equipped with a stirrer, a anhydride into an amber bottle, and dissolve in 300 mL gas dispersion tube, and a vacuum outlet, place 3000 g of pyridine from a freshly opened bottle or pyridine of Polyethylene Glycol 400. At room temperature, that has been freshly distilled over phthalic anhydride. evacuate the flask carefully to a pressure of less than Shake vigorously until completely dissolved. Add 7 g of 1 mm of mercury, applying the vacuum slowly while imidazole, swirl carefully to dissolve, and allow to stand observing for excessive foaming due to entrapped for 16 h before using. gases. After any foaming has subsided and while stirring Sample solution for liquid Polyethylene Glycols: continuously, sparge with nitrogen, allowing the Carefully introduce 25.0 mL of the Phthalic anhydride pressure to rise to 10 mm of mercury. Continue solution into a dry, heat-resistant pressure bottle. Add stripping for a minimum of 1 h. Completeness of the an amount of the specimen equivalent to its expected stripping procedure should be verified by making a average molecular weight divided by 160. Insert the headspace injection of the stripped polyethylene glycol stopper in the bottle, and wrap it securely in a cloth 400. [NOTEÐThe 10-mm value is a guideline. Deviations bag. from this value affect only the total time required to Sample solution for solid Polyethylene Glycols: Care- strip the Polyethylene Glycol 400.] fully introduce 25.0 mL of Phthalic anhydride solution Shut off the vacuum pump, and bring the flask into a dry, heat-resistant pressure bottle. Add an pressure back to atmospheric pressure while amount of the specimen equivalent to its expected mo- maintaining nitrogen sparging. Remove the gas lecular weight divided by 160; however, because of lim- dispersion tube with the gas still flowing, and then turn ited solubility, do not use more than 25 g. Add 25 mL off the gas flow. Transfer the Stripped polyethylene glycol of pyridine, from a freshly opened bottle or pyridine 400 to a suitable nitrogen-filled container. that has been freshly distilled over phthalic anhydride. Standard solution: Transfer 4.90 g of Stripped Swirl to dissolve, insert the stopper in the bottle, and polyethylene glycol 400 to a tared 22-mL pressure wrap it securely in a cloth bag. headspace vial that can be sealed. Add 48 µL of 1,4- Blank: 25.0 mL of Phthalic anhydride solution plus any dioxane, equivalent to 50 mg of 1,4-dioxane, from a additional pyridine added to the bottle syringe; seal; and cap the vial. Analysis: Immerse the bottle in a water bath main- [CAUTIONÐEthylene oxide and 1,4-dioxane are toxic and tained at a temperature between 96° and 100°, to the flammable. Prepare these solutions in a well-ventilated same depth as that of the mixture in the bottle. Re- fume hood.] move the bottles from the bath after 5 min and, with- Using the special handling described in the following, out unwrapping, swirl for 30 s to homogenize. Heat in complete the preparation. Ethylene oxide is a gas at the water bath for 30 min (60 min for Polyethylene room temperature. It is usually stored in a lecture-type Glycols having molecular weights of 3000 or more), gas cylinder or small metal pressure bomb. Chill the then remove from the bath, and allow it to cool to cylinder in a refrigerator before use. Transfer 5 mL of room temperature. Uncap the bottle carefully to release the liquid ethylene oxide to a 100-mL beaker chilled in any pressure, remove from the bag, add 10 mL of wet ice. Using a gas-tight syringe that has been chilled water, and swirl thoroughly. Wait 2 min, add 0.5 mL of in a refrigerator, transfer 57 µL of the liquid ethylene a solution of phenolphthalein in pyridine (1 in 100), oxide, equivalent to 50 mg of ethylene oxide, to the and titrate with 0.5 N sodium hydroxide VS to the first mixture contained in the headspace vial, and mix.