Printed on: Sat Jul 31 2021, 06:09:53 PM Official Status: Currently Official on 31-Jul-2021 DocId: 1_GUID-689CC49B-D676-4822-9F97-1404FD00CF7C_4_en-US
(EST)
Printed by: Le Tran Official Date: Official as of 01-May-2020 Document Type: USP & NF @2021 USPC
1
Impurity Table 1
Propylene Glycol
Relative
Retention
Component Time
Ethylene glycol 0.8
Propylene glycol 1.0
Internal standard 1.7
Diethylene glycol 2.4
C3H8O2 76.09
1,2-Propanediol;
Suitability requirements
Propane-1,2-diol [57-55-6].
Resolution: NLT 5 between ethylene glycol and
DEFINITION propylene glycol
Propylene Glycol contains NLT 99.5% of C3H8O2. Analysis
Sample: Sample solution
IDENTIFICATION Acceptance criteria
[NOTE—Compliance is determined by meeting the Diethylene glycol: If a peak at the retention time for
requirements of Identification tests A, B, and C.] diethylene glycol is present in the Sample solution, the
peak response ratio relative to 2,2,2-trichloroethanol is
Change to read: NMT the peak response ratio for diethylene glycol relative
to 2,2,2-trichloroethanol in the Standard solution: NMT
• A. ▲SPECTROSCOPIC IDENTIFICATION TESTS á197ñ, Infrared
al
0.10% for diethylene glycol.
Spectroscopy: 197F▲ (CN 1-May-2020) Ethylene glycol: If a peak at the retention times for
[NOTE—Undried specimen.] ethylene glycol is present in the Sample solution, the peak
• B. LIMIT OF DIETHYLENE GLYCOL AND ETHYLENE GLYCOL response ratio relative to 2,2,2-trichloroethanol is not
Diluent: Methanol more than the peak response ratio for ethylene glycol
Standard solution: 2.0 mg/mL of USP Propylene Glycol RS, ci relative to 2,2,2-trichloroethanol in the Standard solution:
0.050 mg/mL of USP Ethylene Glycol RS, 0.050 mg/mL of NMT 0.10% for ethylene glycol is found.
USP Diethylene Glycol RS, and 0.10 mg/mL of • C. Examine the chromatograms obtained in Identification
2,2,2-trichloroethanol (internal standard) in methanol test B. The retention time of the propylene glycol peak of
Sample solution: 50 mg/mL of Propylene Glycol and the Sample solution corresponds to that of the Standard
0.10 mg/mL of 2,2,2-trichloroethanol (internal standard) solution.
ffi
in methanol
Chromatographic system ASSAY
(See Chromatography á621ñ, System Suitability.) • PROCEDURE
Mode: GC Sample: Propylene Glycol
Detector: Flame ionization Chromatographic system
Column: 0.53-mm × 30-m fused-silica coated with 3.0-µm (See Chromatography á621ñ, System Suitability.)
O
G43 stationary phase, and a deactivated split liner with Mode: GC
glass wool Detector: Thermal conductivity
Temperature Column: 1-m × 4-mm; 5% phase G16; support S5
Injector: 220° Temperature
Detector: 250° Injector: 240°
Column: See the temperature program table below. Detector: 250°
Column: Increase from 120° to 200° at a rate of 5°/min.
Hold Time
Carrier gas: Helium
Initial Temperature Final at Final Injection size: 10 µL
Temperature Ramp Temperature Temperature [NOTE—The approximate retention time for propylene
(°) (°/min) (°) (min) glycol is 5.7 min, and the approximate retention
100 — 100 4 times for the three isomers of dipropylene glycol,
when present, are 8.2, 9.0, and 10.2 min,
100 50 120 10 respectively.]
120 50 220 6 Analysis: Calculate the percentage of C3H8O2 in the Sample
by dividing the area under the propylene glycol peak by the
Carrier gas: Helium sum of the areas under all of the peaks, excluding those due
Injection size: 1.0 µL to air and water, and multiplying by 100:
Flow rate: 4.5 mL/min Result = [rU/(rU + ΣrU)] × 100
Injection type: The split flow ratio is about 10:1.
System suitability rU = peak response for Propylene Glycol from the
Sample: Standard solution Sample
[NOTE—For informational purposes only. See Impurity ΣrU = sum of individual impurity peak responses,
Table 1 for relative retention times for ethylene glycol, excluding those due to air and water, from the
internal standard, and diethylene glycol. The Sample
retention time for propylene glycol is 4 min.]
Acceptance criteria: NLT 99.5%
https://online.uspnf.com/uspnf/document/1_GUID-689CC49B-D676-4822-9F97-1404FD00CF7C_4_en-US 1/2
Printed on: Sat Jul 31 2021, 06:09:53 PM Official Status: Currently Official on 31-Jul-2021 DocId: 1_GUID-689CC49B-D676-4822-9F97-1404FD00CF7C_4_en-US
(EST)
Printed by: Le Tran Official Date: Official as of 01-May-2020 Document Type: USP & NF @2021 USPC
2
IMPURITIES • ACIDITY
INORGANIC IMPURITIES Sample: 10 mL of Propylene Glycol
• Residue on Ignition á281ñ Analysis: Add 1 mL of phenolphthalein TS to 50 mL of
Sample: 50 g water, then add 0.1 N sodium hydroxide until the solution
Analysis: Heat the Sample in a tared 100-mL shallow dish until remains pink for 30 s. Add the Sample, and titrate with
it ignites, and allow it to burn without further application of 0.10 N sodium hydroxide until the original pink color
heat in a place free from drafts. Cool, moisten the residue returns and remains for 30 s.
with 0.5 mL of sulfuric acid, and ignite to constant weight. Acceptance criteria: NMT 0.20 mL of 0.10 N sodium
Acceptance criteria: The weight of the residue is NMT hydroxide
3.5 mg. • WATER DETERMINATION, Method I á921ñ: NMT 0.2%
• Chloride and Sulfate, Chloride á221ñ: A 1-mL portion shows
no more chloride than corresponds to 0.10 mL of 0.020 N ADDITIONAL REQUIREMENTS
hydrochloric acid (70 ppm). • PACKAGING AND STORAGE: Preserve in tight containers.
• Chloride and Sulfate, Sulfate á221ñ: A 5.0-mL portion • USP REFERENCE STANDARDS á11ñ
shows no more sulfate than corresponds to 0.30 mL of USP Diethylene Glycol RS
0.020 N sulfuric acid (60 ppm). USP Ethylene Glycol RS
USP Propylene Glycol RS
SPECIFIC TESTS
• SPECIFIC GRAVITY á841ñ: 1.035–1.037
al
ci
ffi
O
https://online.uspnf.com/uspnf/document/1_GUID-689CC49B-D676-4822-9F97-1404FD00CF7C_4_en-US 2/2
