Analysis of Ethanol and Isopropanol in Alcoholbased hand sanitizers by direct injection GC/FID

Importance of the topic

Alcohol-based hand sanitizers rely on ethanol or isopropanol as active agents. Accurate quantification of these alcohols is critical for efficacy and compliance with regulatory standards such as USP <611> and ASTM D3695. Robust analytical methods ensure product safety and performance in healthcare and consumer settings.

Objectives and study overview

This study evaluates the performance of Agilent J&W DB-624 Ultra Inert and DB-WAX Ultra Inert GC columns for direct injection GC/FID analysis of ethanol and isopropanol in hand sanitizer formulations. Key goals include assessing chromatographic performance, calibration linearity, and suitability for detecting additional volatile compounds like fusel oils.

Methodology and instrumentation

• Instrument: Agilent 7890 GC with flame ionization detector
• Autosampler: Agilent 7693A with 5 µL syringe
• Columns: DB-624 UI (30 m × 0.32 mm, 1.8 µm) and DB-WAX UI (30 m × 0.25 mm, 0.25 µm)
• Carrier gas: Helium, constant flow 6 mL/min
• Oven program: 40 °C (5 min) then 20 °C/min to 225 °C (2.5 min), total runtime 16.75 min
• Injection: 1 µL, split 40:1, inlet temperature 140 °C

Main results and discussion

Both columns produced sharp, symmetric peaks for high levels of water–alcohol mixtures, demonstrating high inertness. Calibration for isopropanol (30–80 % v/v) yielded R² values of 0.9974 (DB-624 UI) and 0.9991 (DB-WAX UI). Ethanol calibration (50–90 % v/v) showed R² of 0.9955 (DB-624 UI) and 0.9945 (DB-WAX UI). DB-624 UI provided superior resolution for fusel oils present in ethanol-based sanitizers.

Benefits and practical applications

• Direct injection simplifies sample preparation and reduces analysis time.
• High column inertness ensures reproducible retention times and peak shapes in aqueous matrices.
• Wide calibration ranges with excellent linearity support regulatory compliance.
• DB-624 UI allows detection of fermentation by-products such as fusel oils.

Future trends and potential uses

Emerging needs for rapid quality control may drive further miniaturization and automation of GC/FID methods. Advancements in ultra-inert column technologies could expand applications to complex formulations and trace-level impurities. Integration with data analytics and cloud-based monitoring may streamline regulatory reporting and product development.

Conclusion

The Agilent J&W DB-624 UI and DB-WAX UI columns deliver robust performance for quantifying ethanol and isopropanol in hand sanitizers by GC/FID. Both phases exhibit high inertness, reproducible chromatographic behavior, and strong calibration linearity, meeting pharmacopeial requirements. DB-624 UI offers additional selectivity for resolving fusel oils when required.

Reference

1. Isopropyl Alcohol, Monograph US Pharmacopeia, 2020
2. USP <611> Alcohol Determination, Monograph US Pharmacopeia, 2020
3. Temporary policy for preparation of certain alcohol-based hand sanitizers products during the public health emergency, FDA