〈228〉 ETHYLENE OXIDE AND DIOXANE
〈228〉 ETHYLENE OXIDE AND DIOXANE
〈228〉 ETHYLENE OXIDE AND DIOXANE
(EST)
Printed by: Nguyen Nhan Official Date: Official Prior to 2013 Document Type: GENERAL CHAPTER @2021 USPC
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after preparation.]
Ethylene oxide solution: Tare a glass-stoppered conical flask, and chill it in a refrigerator. Add 35 mL of polyethylene glycol
200, and reweigh the flask. Transfer 1 g of chilled Ethylene oxide stock solution to the tared conical flask. Adjust the weight
of the solution with polyethylene glycol 200 to 50.0 g, replace the stopper, and swirl gently to mix. Transfer 10 g of this
solution to a 50-mL volumetric flask. Add 30 mL of water, and mix. Dilute with water to volume, and mix to obtain a
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solution containing 10 µg/mL of ethylene oxide. [NOTE—Use an adequately chilled apparatus where appropriate. Prepare
immediately before use.]
Dioxane solution: 500 µg/mL of dioxane
Standard solution A: Transfer 0.1 mL of Ethylene oxide solution to a 10-mL pressure headspace vial. [NOTE—Other sizes such
as a 22-mL pressure headspace vial may be used, depending on operating conditions; however, the same size must be
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used for Standard solution A, Standard solution B, and the Sample solution.] Add 0.1 mL of Acetaldehyde solution and 0.1 mL
of Dioxane solution, seal the vial, and mix.
Standard solution B: Transfer 1.0 g of the test substance to a 10-mL pressure headspace vial, and add 0.1 mL of Ethylene
oxide solution, 0.1 mL of Dioxane solution, and 1.0 mL of N,N-dimethylacetamide. Seal the vial, and mix.
Sample solution: Transfer 1.0 g of the test substance to a 10-mL pressure headspace vial, and add 1.0 mL of
N,N-dimethylacetamide and 0.2 mL of water. Seal the vial, and mix.
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Chromatographic system
(See Chromatography á621ñ, System Suitability.)
Mode: Headspace GC
Detector: Flame ionization
Column: 0.32-mm × 30-m glass or quartz capillary; 1.0-µm layer of phase G1
Temperature
Injector port: 150°
Detector: 250°
Column: See the column temperature table below.
50 5 180 —
180 30 230 5
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System suitability
Sample: Standard solution A
[NOTE—The relative retention times for acetaldehyde and ethylene oxide are 0.94 and 1.0, respectively.]
Suitability requirements
Resolution: NLT 2.0 between acetaldehyde and ethylene oxide
Signal-to-noise ratio: NLT 5, determined from the dioxane peak
Relative standard deviation: NMT 15%
Analysis
Samples: Standard solution B and Sample solution
[NOTE—The relative retention times for ethylene oxide and dioxane are 1.0 and 2.5, respectively.]
Calculate the content of ethylene oxide, in ppm, in the portion of the test substance taken:
Calculate the content of dioxane, in ppm, in the portion of the test substance taken:
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Result = AD × rU/[(rS × WU) − (rU × WS)]
Method II
Ethylene oxide standard solution: Dilute 0.5 mL of ethylene oxide in methylene chloride (50 mg/mL)1 with water to
50.0 mL. [NOTE—The solution is stable for 3 months if stored in vials with polytetrafluoroethylene (polytef)-coated silicon
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membrane crimped caps at −20°.] Allow to reach room temperature. Dilute 1.0 mL with water to 250.0 mL to obtain a
solution having a concentration of 2 µg/mL of ethylene oxide. [NOTE—Use this solution immediately after preparation.]
Dioxane standard solution: 0.05 µL/mL of dioxane
Acetaldehyde standard solution: 10 µg/mL of acetaldehyde. [NOTE—Prepare immediately before use.]
Resolution solution: Add 2.0 mL of Acetaldehyde standard solution and 2.0 mL of Ethylene oxide standard solution to a 10-mL
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headspace vial. Seal the vial immediately with a polytef-coated silicon membrane and an aluminum cap, and mix carefully.
Standard solution A: 0.48 µg/mL of ethylene oxide, from Ethylene oxide standard solution, and 0.005 µL/mL of dioxane,
from Dioxane standard solution, in water
Standard solution B: Transfer 1.0 g of the test substance into a 10-mL headspace vial. Add 2.0 mL of Standard solution A,
seal the vial immediately with a polytef-coated silicon membrane and an aluminum cap, and mix carefully.
Sample solution: Transfer 1.0 g of the test substance into a 10-mL headspace vial. Add 2.0 mL of water, seal the vial
immediately with a polytef-coated silicon membrane and an aluminum cap, and mix carefully.
Chromatographic system
(See Chromatography á621ñ, System Suitability.)
Mode: Headspace GC
Detector: Flame ionization
Column: 0.53-mm × 50-m fused-silica capillary column; 5.0-µm layer of phase G27
Temperature
Injector port: 85°
Detector: 250°
Column: See the column temperature table below.
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System suitability
Sample: Resolution solution
[NOTE—The relative retention times for acetaldehyde and ethylene oxide are 0.9 and 1.0, respectively.]
Suitability requirements
Resolution: NLT 2.0 between acetaldehyde and ethylene oxide
Analysis
Samples: Standard solution B and Sample solution
[NOTE—The relative retention times for ethylene oxide and dioxane are 1.0 and 1.9, respectively.]
Calculate the content of ethylene oxide, in ppm, in the portion of the test substance taken:
Calculate the content of dioxane, in ppm, in the portion of the test substance taken:
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CD = concentration of dioxane in Standard solution A (µL/mL)
V = volume of Standard solution A added to Standard solution B (2.0 mL)
ρ = density of dioxane (1.03 g/mL = 1.03 mg/µL)
F = conversion factor (1000 µg/mg)
rU = dioxane peak responses from the Sample solution
rS
WU
WS
= dioxane peak responses from Standard solution B
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= weight of the test substance taken to prepare the Sample solution (g)
= weight of the test substance taken to prepare Standard solution B (g)
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