Quantitative determination of volatile impurities in ethanol used for hand sanitizers

Importance of the Topic

The emergence of COVID-19 triggered a surge in hand sanitizer use, making the control of volatile impurities in ethanol-based disinfectants essential. European Pharmacopeia guidelines impose strict limits on contaminants such as methanol, acetaldehyde, benzene and other volatile organics to protect human health.

Objectives and Study Overview

This study aimed to quantify regulated volatile impurities in ethanol for hand sanitizers according to European Pharmacopeia requirements. Specific goals included:

• Measurement of methanol, acetaldehyde, 1,1-diethoxyethane, benzene, and 4-methylpentan-2-ol.
• Verification of system suitability via chromatographic resolution.
• Quantification by comparing test solutions spiked with reference standards.

Methodology and Instrumentation

Analyses were performed by gas chromatography with flame ionization detection (GC-FID). Key parameters were:

• Instrument: Shimadzu GC-2030 with FID-2030 detector
• Column: SH-Rtx-624, 30 m × 0.32 mm ID, 1.8 µm film thickness
• Carrier gas: Helium, linear velocity 35.0 cm/s
• Injection: Split 1:20, 1 µL at 200 °C
• Oven program: 40 °C for 12 min, ramp at 10 °C/min to 240 °C, hold 10 min (total 42 min)

Main Results and Discussion

All target analytes eluted within 18 min. System suitability was confirmed by a resolution of 1.54 between acetaldehyde and methanol peaks (>1.5 required). Key findings:

• Methanol: test solution peak area 452 vs. reference 34 787 (RSD ≤ 7.8 %), corresponding to <50 % of the 200 ppm limit.
• Acetaldehyde + 1,1-diethoxyethane: combined concentration 0.361 ppm (limit 10 ppm).
• Benzene: not detected, below the 2 ppm threshold.
• Aggregate other impurities: total peak area (17 941) significantly lower than the 4-methylpentan-2-ol reference (153 375).

Benefits and Practical Applications

This validated GC-FID method provides:

• Accurate quantification of trace impurities in sanitizer-grade ethanol.
• Compliance with Pharmacopeial requirements for QC laboratories.
• Fast analysis with clear separation of regulated compounds.

Future Trends and Potential Applications

Further improvements may include advanced stationary phases and detectors to reduce detection limits. Integration of automated, high-throughput GC systems can enhance routine QC capacity. Coupling GC-FID with mass spectrometry could improve identification of unknown volatiles in complex matrices.

Conclusions

The described GC-FID approach reliably measures critical volatile impurities in ethanol at levels mandated by the European Pharmacopeia, supporting manufacturers and regulators in ensuring hand sanitizer safety and quality.

Reference

• Statista. Hand sanitizer sales growth in Germany after COVID-19 outbreak. June 2020.
• World Health Organization. Guidelines on hand hygiene in health care. July 2020.
• European Pharmacopoeia, 10th Edition. Monograph “Ethanol (96 per cent)”. July 2019.