Propylene glycol, Diethylene glycol, Ethylene glycol

Significance of the Topic

Quantitative analysis of low–molecular-weight glycols such as ethylene glycol, propylene glycol and diethylene glycol is critical in pharmaceutical quality control, environmental monitoring and chemical manufacturing. Accurate determination of these polar compounds helps ensure product safety, regulatory compliance and process optimization.

Objectives and Overview

This application note demonstrates a gas chromatographic method with flame ionization detection (GC/FID) for the separation and quantification of ethylene glycol, propylene glycol and diethylene glycol. The study aims to achieve baseline resolution of all three analytes within a short runtime using an inert capillary column.

Methodology

A methanolic standard solution containing each glycol at 500 μg/mL was injected (1.0 μL) in split mode. The temperature program started at 100 °C, ramped at 7.5 °C/min to 220 °C, and held to elute higher-boiling species. Helium at 80 kPa served as carrier gas. GC/FID provided quantitative detection under robust conditions suitable for routine analysis.

Instrumentation Used

• Gas chromatograph with FID detector
• InertCap® 1701 capillary column (0.32 mm I.D. × 30 m, 1.00 μm film thickness)
• Split injection (40 mL/min), injector at 220 °C
• Detector temperature: 250 °C
• Carrier gas: He, 80 kPa

Main Results and Discussion

The chromatogram displayed three well-resolved peaks with retention times near 4, 6 and 8 minutes corresponding to ethylene glycol, propylene glycol and diethylene glycol, respectively. The inert surface of the column minimized peak tailing and sample adsorption, ensuring sharp peak shapes. Total analysis time was under 15 minutes, demonstrating high throughput.

Benefits and Practical Applications

• High resolution and reproducibility for polar analytes
• Short runtime suitable for routine QC workflows
• Inert column chemistry reduces active site interactions
• Applicable to pharmaceutical, food and environmental testing

Future Trends and Potential Uses

Coupling inert GC columns with mass spectrometric detection can enhance selectivity for trace-level glycols in complex matrices. Development of faster temperature programs and miniaturized systems will further shorten analysis times. Integration with automated sample preparation platforms can improve throughput in high-volume laboratories.

Conclusion

The presented GC/FID method offers a reliable, fast and reproducible approach for the analysis of ethylene glycol, propylene glycol and diethylene glycol. The inert capillary column ensures minimal sample-column interactions, making the method ideal for routine quality control and environmental monitoring.

Reference

No literature references were provided in the original document.