Analysis of Ethylene Glycol and Diethylene Glycol in Propylene Glycol

Importance of the Topic

The presence of ethylene glycol and diethylene glycol in propylene glycol poses health and regulatory concerns in pharmaceutical, cosmetic and food industries. Reliable detection and quantification of these toxic impurities ensure product safety and compliance with pharmacopeial standards.

Study Objectives and Overview

This application note from Shimadzu demonstrates a gas chromatographic method with flame ionization detection for simultaneous analysis of ethylene glycol and diethylene glycol in a propylene glycol matrix. The goal is to achieve clear separation and accurate determination at pharmacopeia-required levels.

Methodology

A detailed temperature-programmed GC method is used to resolve target glycols. Sample injections of 1 µL are performed in split mode under defined conditions. Key parameters include:

• Column: SH-1701, 30 m × 0.32 mm I.D., 1.0 µm film
• Oven Program: 100 °C initial, ramp 7.5 °C/min to 220 °C, hold 4 min
• Carrier Gas: Helium at 38 cm/s
• Injector Temp: 220 °C, Detector Temp: 250 °C
• Split Ratio: 1:20

Used Instrumentation

This method employs a Shimadzu GC-2010 Plus gas chromatograph coupled with an AOC-20i autosampler and a flame ionization detector. The SH-1701 capillary column provides selectivity for polyol separation.

Main Results and Discussion

Under the described conditions, ethylene glycol, propylene glycol and diethylene glycol are baseline separated within a single run. Calibration at 0.5 mg/mL for each analyte shows linear response and satisfactory sensitivity. The method delivers reproducible retention times and peak areas, demonstrating robust performance for routine quality control.

Benefits and Practical Applications

The described GC-FID approach offers:

• High specificity and sensitivity for glycol impurities
• Compliance with Japanese Pharmacopoeia 16th edition requirements
• Rapid analysis suitable for high-throughput laboratories
• Minimal sample preparation and straightforward data interpretation

Future Trends and Potential Applications

Further enhancements may include coupling to mass spectrometry for confirmatory analysis, adoption of faster temperature ramps or shorter columns to reduce run times, and integration with automated data processing for improved laboratory efficiency.

Conclusion

This application note validates a robust GC-FID method for simultaneous quantification of ethylene glycol and diethylene glycol in propylene glycol. The procedure supports regulatory compliance and ensures product safety in pharmaceutical and related industries.

References

Shimadzu Application News G282, First Edition September 2022, ERAS-1000-0305.