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Accessed from 128.83.63.20 by nEwp0rt1 on Tue Nov 29 23:26:34 EST 2011

NF 30 Official Monographs / Polyethylene 1903

CU = concentration of Polyethylene Glycol in the is within the limits specified in Table 3. For a Polyethylene Sample solution (mg/mL) Glycol not listed in the table, calculate the limits by Calculate the percentage of in the portion interpolation. of Polyethylene Glycol taken: Table 3 Result = (rU2/rS2) × (CS2/CU) × 100 Nominal Nominal rU2 = peak height of diethylene glycol from the Sample Average Average Viscosity solution Molecular Range, Molecular Range, rS2 = peak height of diethylene glycol from the Weight Centistokes Weight Centistokes Standard solution 200 3.9–4.8 2400 49–65 CS2 = concentration of diethylene glycol in the 300 5.4–6.4 2500 51–70 Standard solution (mg/mL) 400 6.8–8.0 2600 54–74 CU = concentration of Polyethylene Glycol in the Sample solution (mg/mL) 500 8.3–9.6 2700 57–78 Acceptance criteria: NMT 0.25% of the sum of 600 9.9–11.3 2800 60–83 glycol and diethylene glycol is found. 700 11.5–13.0 2900 64–88 • LIMIT OF AND DIETHYLENE GLYCOL (for 800 12.5–14.5 3000 67–93 Polyethylene Glycol having a nominal molecular weight 450 900 15.0–17.0 3250 73–105 or more but NMT 1000) Ceric ammonium solution: 6.25 g of ceric 1000 16.0–19.0 3350 76 –110 ammonium nitrate in 100 mL of 0.25 N nitric acid. Use 1100 18.0–22.0 3500 87–123 within 3 days. 1200 20.0–24.5 3750 99–140 Standard stock solution: 2.5 mg/mL of diethylene glycol in 1300 22.0–27.5 4000 110–158 1:1 freshly distilled : 1400 24–30 4250 123–177 Sample stock solution: Dissolve 50.0 g of Polyethylene 1450 25–32 4500 140–200 Glycol in 75 mL of diphenyl , previously warmed if necessary, just to melt the crystals, in a 250-mL distilling 1500 26–33 4750 155–228 flask. Slowly distill at a pressure of 1–2 mm of mercury, into 1600 28–36 5000 170–250 a receiver graduated to 100 mL in 1-mL subdivisions, until 1700 31–39 5500 206–315 25 mL of distillate has been collected. Add 20.0 mL of water 1800 33–42 6000 250–390 to the distillate, shake vigorously, and allow the layers to 1900 35–45 6500 295–480 separate. Cool in an ice bath to solidify the diphenyl ether 2000 38–49 7000 350–590 and facilitate its removal. Filter the separated aqueous layer, wash the diphenyl ether with 5.0 mL of ice-cold water, pass 2100 40–53 7500 405–735 the washings through the filter, and collect the filtrate and 2200 43–56 8000 470–900 washings in a 25-mL volumetric flask. Warm to room 2300 46–60 — — temperature, and dilute with water to volume, if necessary. Mix this solution with 25.0 mL of freshly distilled acetonitrile ADDITIONAL REQUIREMENTS in a glass-stoppered, 125-mL conical flask. • PACKAGING AND STORAGE: Preserve in tight containers. Standard solution: Add 10.0 mL of the Standard stock • LABELING: Label it to state, as part of the official title, the solution to 15.0 mL of Ceric ammonium nitrate solution. average nominal molecular weight of the Polyethylene Within 2–5 min, determine the absorbance of the Standard Glycol. Label it to indicate the name and quantity of any solution. added antioxidant. Sample solution: Add 10.0 mL of the Sample stock solution to 15.0 mL of Ceric ammonium nitrate solution. Within 2–5 min, determine the absorbance of the Sample solution.

Blank: Mixture of 15.0 mL of Ceric ammonium nitrate . solution and 10.0 mL of 1:1 freshly distilled acetonitrile:water Instrumental conditions Polyethylene Glycol Ointment (See Spectrophotometry and Light-Scattering 〈851〉.) Mode: UV-Vis » Prepare Polyethylene Glycol Ointment as Cell: 1 cm follows: Analytical wavelength: 450 nm Analysis Samples: Standard solution and Sample solution Polyethylene Glycol 3350 ...... 400 g Acceptance criteria: The absorbance of the Sample solution Polyethylene Glycol 400 ...... 600 g does not exceed that of the Standard solution, corresponding to NMT 0.25% of combined ethylene glycol to make ...... 1000 g and diethylene glycol. Heat the two ingredients on a water bath to 65°. SPECIFIC TESTS Allow to cool, and stir until congealed. If a firmer • PH 〈791〉 preparation is desired, replace up to 100 g of the Sample solution: 5.0 g of Polyethylene Glycol in 100 mL of polyethylene glycol 400 with an equal amount of -free water. Add 0.30 mL of saturated potassium chloride solution. polyethylene glycol 3350. Acceptance criteria: 4.5–7.5 NOTE—If 6 percent to 25 percent of an aqueous • COMPLETENESS AND COLOR OF SOLUTION: A solution of 5 g of solution is to be incorporated in Polyethylene Polyethylene Glycol in 50 mL of water is colorless; it is clear Glycol Ointment, replace 50 g of the polyethyl- for liquid grades and NMT slightly hazy for solid grades. • VISCOSITY 〈911〉: Determine its viscosity by using a capillary ene glycol 3350 with an equal amount of stearyl viscosimeter giving a flow time of NLT 200 s and using a alcohol. liquid bath maintained at 98.9 ± 0.3° (210° F). The viscosity

Official from May 1, 2012 Copyright (c) 2011 The United States Pharmacopeial Convention. All rights reserved. Accessed from 128.83.63.20 by nEwp0rt1 on Tue Nov 29 23:26:34 EST 2011

1904 Polyethylene / Official Monographs NF 30

Packaging and storage—Preserve in well-closed containers. bath, and allow it to cool to room temperature. Uncap the bottle carefully to release any pressure, remove from the bag, add 10 mL of water, and swirl thoroughly. Wait for 2 minutes, add 0.5 mL of a solution of in pyridine (1 in . 100), and titrate with 0.5 N VS to the first Polyethylene Glycol Monomethyl Ether pink color that persists for 15 seconds, recording the volume, in Poly(oxy-1,2-ethanediyl), α-methyl-ω-hydroxy-. mL, of 0.5 N sodium hydroxide required as S. Perform a blank Methoxy polyethylene glycol [9004-74-4]. determination on 25.0 mL of Phthalic anhydride solution plus any additional pyridine added to the bottle, and record the » Polyethylene Glycol Monomethyl Ether is an volume, in mL, of 0.5 N sodium hydroxide required as B. Calcu- addition of and metha- late the average molecular weight by the formula: nol, represented by the formula: [1000W] / [(B − S)(N)]

CH3(OCH2CH2)nOH in which W is the weight, in g, of the Polyethylene Glycol Monomethyl Ether taken for the Test preparation; (B − S) is the in which n represents the average number of difference between the volumes of 0.5 N sodium hydroxide oxyethylene groups. The average molecular consumed by the blank and by the specimen; and N is the weight is not less than 95.0 percent and not normality of the sodium hydroxide solution. more than 105.0 percent of the labeled nominal Nominal Nominal value if the labeled nominal value is below 1000; Average Viscosity Average Viscosity it is not less than 90.0 percent and not more Molecular Range, Molecular Range, than 110.0 percent of the labeled nominal value Weight Centistokes Weight Centistokes if the labeled nominal value is between 1000 and 350 3.5 to 4.5 2750 50 to 78 4750; it is not less than 87.5 percent and not 450 4.9 to 6.0 3000 60 to 95 more than 112.5 percent of the labeled nominal 550 6.1 to 7.3 3250 72 to 113 value if the labeled nominal value is above 4750. 650 7.9 to 9.2 3500 85 to 133 750 9.7 to 11.1 3750 99 to 155 Packaging and storage—Preserve in tight containers. 850 11.5 to 13.1 4000 114 to 178 Labeling—Label it to state, as part of the official title, the aver- 950 13.3 to 15.2 4250 130 to 204 age nominal molecular weight of the Polyethylene Glycol 1000 13.3 to 17.3 4500 148 to 231 Monomethyl Ether. 1100 15.0 to 19.7 4750 167 to 260 Completeness and color of solution—A solution of 5 g of Polyethylene Glycol Monomethyl Ether in 50 mL of water is 1200 16.9 to 22.1 5000 175 to 305 colorless; it is clear for liquid grades and not more than slightly 1300 18.8 to 24.6 5500 215 to 375 hazy for solid grades. 1400 20.7 to 27.1 6000 260 to 455 Viscosity 〈911〉—Determine its viscosity, using a capillary visco- 1500 23 to 30 6500 310 to 545 simeter giving a flow time of not less than 200 seconds, and a 1600 25 to 33 7000 365 to 640 liquid bath maintained at 98.9 ± 0.3° C (210° F). The viscosity 1700 27 to 35 7500 425 to 745 is within the limits specified in the accompanying table. For a 1800 29 to 38 8000 490 to 860 Polyethylene Glycol Monomethyl Ether not listed in the table, calculate the limits by interpolation. 1900 31 to 41 8500 560 to 980 2000 33 to 44 9000 640 to 1110 Average molecular weight— 2250 36 to 54 9500 715 to 1250 Phthalic anhydride solution—Place 49.0 g of phthalic anhy- dride into an amber bottle, and dissolve in 300 mL of pyridine 2500 40 to 64 10000 775 to 1475 from a freshly opened bottle or that has been freshly distilled over phthalic anhydride. Shake vigorously until completely dis- pH 〈791〉: between 4.5 and 7.5, determined potentiometri- solved. Add 7 g of imidazole, swirl carefully to dissolve, and cally, in a solution prepared by dissolving 5.0 g of Polyethylene allow to stand for 16 hours before using. Glycol Monomethyl Ether in 100 mL of carbon dioxide-free Test preparation for liquid Polyethylene Glycol Monomethyl water and adding 0.30 mL of saturated potassium chloride —Carefully introduce 25.0 mL of the Phthalic anhydride solution. solution into a dry, heat-resistant pressure bottle. Add an accu- Residue on ignition 〈281〉: not more than 0.1%, a 25-g rately weighed amount of the specimen, equivalent to its ex- specimen and a tared platinum dish being used, and the resi- pected average molecular weight divided by 80. Insert the stop- due being moistened with 2 mL of sulfuric acid. per in the bottle, and wrap it securely in a cloth bag. Heavy metals 〈231〉—Mix 4.0 g with 5.0 mL of 0.1 N hydro- Test preparation for solid Polyethylene Glycol Monomethyl chloric acid, and dilute with water to 25 mL: the limit is 5 ppm. Ethers—Carefully introduce 25.0 mL of Phthalic anhydride solu- Free ethylene oxide and 1,4-dioxane— tion into a dry, heat-resistant pressure bottle. Add an accurately Stripped MPEG 350—Into a 5000-mL 4-neck, round-bottom weighed amount of the specimen, equivalent to its expected flask, equipped with a stirrer, a thermometer, a gas dispersion molecular weight divided by 80; however, because of limited tube, a dry ice trap, a vacuum outlet, and a heating mantle, solubility, do not use more than 25 g. Add 25 mL of pyridine, place 3000 g of Polyethylene Glycol Monomethyl Ether 350. At from a freshly opened bottle or that has been freshly distilled room temperature, evacuate the flask carefully to a pressure of over phthalic anhydride, swirl to dissolve, insert the stopper in less than 1 mm of mercury, applying the vacuum slowly while the bottle, and wrap it securely in a cloth bag. observing for excessive foaming due to entrapped gases. After Procedure—Immerse the bottle in a water bath maintained at any foaming has subsided, sparge with nitrogen, allowing the a temperature between 96° and 100°, to the same depth as pressure to rise to 10 mm of mercury. Heat the flask to 130° that of the mixture in the bottle. Remove the bottles from the while increasing the pressure to about 60 mm of mercury. Con- bath after 5 minutes, and, without unwrapping, swirl for 30 tinue stripping for 4 hours; then cool to room temperature. seconds to homogenize. Heat in the water bath for 30 minutes Shut off the vacuum pump, and bring the flask pressure back to (60 minutes for Polyethylene Glycol Monomethyl Ethers having atmospheric pressure while maintaining nitrogen sparging. Re- molecular weights of 3000 or higher), then remove from the move the sparging tube with the gas still flowing, then turn off

Official from May 1, 2012 Copyright (c) 2011 The United States Pharmacopeial Convention. All rights reserved.