Analysis of Methanol in Ethanol-based Sanitizer - No. 353

Analysis of Methanol in Ethanol-based Sanitizers

Importance of the Topic

Ethanol-based hand sanitizers are essential for public health and hygiene. Ensuring these products are free from toxic impurities such as methanol is critical to consumer safety and regulatory compliance. Accurate quantification of methanol helps manufacturers maintain quality control and supports authorities in enforcing safety standards.

Aims and Study Overview

This study demonstrates a gas chromatography–flame ionization detection (GC–FID) method for the determination of methanol in both liquid and gel ethanol-based sanitizers. The primary objectives are to achieve baseline separation of methanol from ethanol and other common volatiles, and to validate the method for routine quality assurance.

Methodology

A Shimadzu Nexis GC-2030 system coupled with an AOC-20i Plus autosampler and an FID-2030 detector was employed. Chromatographic separation was achieved on a 30 m × 0.32 mm I.D. SH-Wax column with a 0.50 µm film thickness. The oven program started at 40 °C (held for 5 min), ramped at 10 °C/min to 100 °C, and held for 2 min, yielding a total run time of 13 min. Injector and detector temperatures were set at 250 °C. Samples (1 µL) were introduced in split mode (1:100) with helium carrier gas at 1 mL/min (constant flow). FID gases: H₂ at 32 mL/min, He makeup at 24 mL/min, air at 200 mL/min.

Used Instrumentation

• GC System: Nexis GC-2030
• Autosampler: AOC-20i Plus
• Detector: FID-2030
• Column: SH-Wax, 30 m × 0.32 mm I.D., 0.50 µm film

Main Results and Discussion

Chromatograms of both liquid and gel samples showed clear separation of methanol (peak 1), ethyl acetate (peak 2), and ethanol (peak 3) within 13 minutes. Calibration using standards at 63 ppm and 630 ppm methanol produced linear responses, demonstrating the method’s suitability for detecting trace to moderate levels of contamination. Sample preparation involved dilution of liquid sanitizers with water and gel formulations with ethanol, ensuring matrix compatibility.

Benefits and Practical Applications

• Rapid analysis with a short runtime supports high-throughput testing in manufacturing and regulatory labs.
• High sensitivity and selectivity for methanol ensure product safety.
• Simple sample preparation procedures facilitate routine implementation.

Future Trends and Possibilities

Advances may include coupling GC with mass spectrometry for enhanced specificity, automation of sample preparation to reduce labor, and development of portable GC systems for field testing. Further work on green chromatography—using alternative carrier gases or solventless sample introduction—could reduce environmental impact.

Conclusion

The presented GC–FID method on the SH-Wax column offers a reliable, efficient approach for quantifying methanol in ethanol-based sanitizers. It meets the demands of quality control and regulatory monitoring, ensuring consumer safety.

References

• Shimadzu Application News G337 (JP, ENG)
• Shimadzu Corporation, First Edition: Sep. 2022, ERAS-1000-0353