Fast, cost-effective quantification of alcohol content in hand sanitizers by direct injection GC-FID

Significance of the Topic

Hand sanitizers containing high concentrations of ethanol or isopropanol are essential for infection control, notably during the COVID-19 pandemic. Accurate quantification of alcohol content ensures product efficacy, regulatory compliance, and consumer safety.

Goals and Overview of the Study

This study demonstrates a rapid, cost-effective gas chromatography method with flame ionization detection for determining ethanol (USP <611>) and isopropanol in hand sanitizers. The method shortens chromatographic run time and expands the analysis scope to include isopropanol.

Applied Methodology and Instrumentation

Samples and standards were diluted to 2% v/v and directly injected into a Thermo Scientific TRACE 1310 GC-FID equipped with an iC-SSL injector and an AS 1310 autosampler. Separation utilized a TraceGOLD TG-624 SilMS capillary column with a HydroGOLD guard column. Chromeleon CDS software controlled instrument setup, data acquisition, and quantitation in compliance with FDA 21 CFR Part 11.

Used Instrumentation

• Thermo Scientific TRACE 1310 Gas Chromatograph with iC-SSL Split/Splitless injector
• TRACE 1310 AS 1310 liquid autosampler
• Flame ionization detector (iC-FID)
• TraceGOLD TG-624 SilMS column (30 m × 0.53 mm × 3.0 µm) with HydroGOLD guard
• Thermo Scientific Chromeleon CDS software v7.3

Main Results and Discussion

The modified USP <611> Method IIb delivered baseline separation of ethanol, isopropanol, and acetonitrile (IS) in under 3 minutes. System suitability tests for 10 consecutive standard injections showed asymmetry factors <1.1, resolutions of 7.05 (ethanol/IS) and 2.19 (IPA/IS), and %RSD of peak area ratios below 0.5%. Quantitative analysis of commercial hand sanitizers matched label claims within ±2% v/v. Robustness testing over 200 injections confirmed stable retention times (%RSD ≤0.04%) and peak area ratios (%RSD ~1.9%) with no maintenance required.

Benefits and Practical Applications of the Method

• Fast run time enables analysis of ~144 samples per day versus ~50 with traditional methods
• High inertness and direct water injections reduce maintenance and downtime
• Cost-effective for pharmaceutical QA/QC laboratories with high throughput demands
• Comprehensive data integrity and reporting via Chromeleon CDS

Future Trends and Opportunities

Future developments may include method adaptation for additional alcohols and complex matrices, integration with automated sample preparation workflows, coupling to mass spectrometric detectors for enhanced selectivity, and further reduction of solvent usage to support green analytical chemistry initiatives.

Conclusion

The Thermo Scientific TRACE 1310 GC-FID method offers a rapid, robust, and compliant solution for accurate measurement of ethanol and isopropanol in hand sanitizers. Shortened analysis time, reliable performance, and streamlined data management make it well suited for high-throughput quality control settings.

References

1. World Health Organization. Hand hygiene and COVID-19. WHO, 2020.
2. USP <611> Alcohol Determination, United States Pharmacopeia, 2020.
3. General Notices and Requirements USP <38>, United States Pharmacopeia, 2015.
4. General Chapter USP <621> Chromatography, First Supplement to USP 40-NF 35, 2017.