Glycerin, Diethylene glycol, Ethylene glycol

Importance of the Topic

Determination of glycerin, ethylene glycol, and diethylene glycol in pharmaceutical and industrial samples is essential for ensuring product safety and quality. These polyols and glycols can be toxic at elevated levels, so reliable analytical methods are critical in quality control, regulatory compliance, and process monitoring.

Objectives and Study Overview

This application note demonstrates a gas chromatography–flame ionization detection (GC–FID) method using an InertCap 1701 capillary column. The goal is to achieve rapid, baseline separation of three analytes—ethylene glycol, diethylene glycol, and glycerin—in a single run, with robust performance suitable for routine analysis.

Methodology and Instrumentation

Instrumentation:

• Gas chromatograph equipped with FID
• InertCap 1701 column (30 m × 0.32 mm I.D., 1.0 µm film thickness)
• Carrier gas: helium at 80 kPa
• Injection: split mode, 40 mL/min, injector at 220 °C
• FID conditions: detector at 250 °C, range 100

Chromatographic conditions:

• Column temperature program: start at 100 °C, ramp at 7.5 °C/min to 220 °C
• Sample: 500 µg/mL in methanol, injection volume 1.0 µL

Main Results and Discussion

The method accomplished clear separation within 15 minutes. Retention times were well resolved: ethylene glycol eluted first, followed by diethylene glycol, and finally glycerin. The baseline separation was confirmed by a representative chromatogram. Peak shapes were symmetrical, indicating minimal interaction with active sites. The inert surface treatment of the InertCap 1701 column minimized adsorption of polar analytes, ensuring sharp peaks and reproducible retention.

Benefits and Practical Applications

This GC–FID approach offers:

• High throughput with short analysis time
• Accurate quantitation of low‐volatility, polar compounds
• Versatility for quality control in pharmaceutical, food, and environmental laboratories

The method supports regulatory testing and contamination screening in manufacturing processes.

Future Trends and Potential Applications

Advancements in column surface treatments and detector sensitivity will further reduce detection limits and improve robustness. Coupling with mass spectrometry could enable simultaneous identification of additional impurities. Miniaturized GC systems may facilitate on‐site screening in industrial plants or field laboratories.

Conclusion

The described GC–FID method using an InertCap 1701 column provides a reliable, efficient solution for analyzing ethylene glycol, diethylene glycol, and glycerin. Its simplicity and robustness make it suitable for routine QC applications, ensuring product safety and compliance.

Reference

GA209-0644, GL Sciences Inc.