Analysis of Impurities in Alcohol-Based Hand Sanitizers by GC-MS

Significance of the Topic

This application note addresses the critical need for reliable quality control of alcohol-based hand sanitizers by enabling simultaneous quantification of regulated impurities and active alcohol content. Trace levels of toxic contaminants such as methanol or benzene pose significant health risks, and a robust, single-run GC-MS method supports rapid evaluation of liquid and gel sanitizer formulations.

Objectives and Study Overview

The study adapts the FDA’s direct injection GC-MS procedure for listed impurities in hand sanitizers to a Shimadzu GCMS-QP2020 NX platform. It aims to demonstrate method performance—precision, accuracy, linearity, and dynamic range—for Level 1 and Level 2 impurities and ethanol content. The potential for untargeted screening of non-listed compounds is also evaluated using FASST mode.

Methodology and Instrumentation

• Sample Preparation: Spiked recovery standards and three commercial ethanol-based sanitizers (two liquid, one gel) at ~80% v/v alcohol.
• Chromatographic Conditions: Shimadzu GCMS-QP2020 NX with AOC-20i Plus injector and AOC-20s Plus autosampler; SH-Rtx-624 column (30 m×0.25 mm, 1.4 μm); injection 250 °C split 50:1; He carrier at 1 mL/min; oven 40 °C (5 min) → 240 °C at 30 °C/min.
• Mass Spectrometry: Electron ionization source at 230 °C; interface 240 °C; FASST mode alternating scan (m/z 29–300) and SIM for target ions.

Instrumentation

• GC-MS System: Shimadzu GCMS-QP2020 NX
• Auto Injector: AOC-20i Plus
• Autosampler: AOC-20s Plus
• Analytical Column: SH-Rtx-624 (30 m×0.25 mm I.D., 1.4 μm)
• Carrier Gas: Helium

Main Results and Discussion

• Calibration: Six-point curves for 13 impurities and ethanol showed excellent linearity (R²>0.999) across µg/mL to ppm ranges.
• Precision and Accuracy: System suitability achieved %RSD<2.5 for all impurities; recovery rates ranged 90–110% in spiked tests.
• Impurity Findings: In two liquid sanitizers, sanitizer 1 contained acetaldehyde (32.5 ppm) and methanol (31.4 ppm); sanitizer 2 showed elevated levels of 1-propanol, ethyl acetate, isobutanol, acetal, and 3-methyl-1-butanol. The gel sanitizer was free of listed impurities.
• Alcohol Content: Ethanol percentages measured at 70.5%, 77.6%, and 78.0% v/v matched expected formulation strengths.
• Untargeted Screening: FASST analysis identified 2-methyl-1-butanol, a non-listed impurity, in the sake-brewer sanitizer sample.

Benefits and Practical Applications

• Single-run method quantifies both alcohol and a broad panel of regulated impurities under fixed conditions.
• Wide dynamic range accommodates low-level toxicants and high-concentration solvents without method changes.
• FASST mode integrates targeted SIM quantitation with full‐scan screening for unexpected contaminants.
• Validated for both liquid and gel hand sanitizer matrices, streamlining QA/QC workflows.

Future Trends and Opportunities

Advancements in GC-MS technology, including high-throughput sample handling and enhanced data analytics, will further accelerate quality control of sanitizers. Portable GC-MS systems and cloud-based spectral libraries may enable on-site screening. Expanding similar methodologies to other disinfectant and personal care products can ensure broader consumer safety.

Conclusion

The Shimadzu GCMS-QP2020 NX method, aligned with FDA guidelines, demonstrated robust performance for simultaneous determination of listed impurities and ethanol in hand sanitizers. High precision, accuracy, and sensitivity across a wide concentration range, combined with FASST screening, offer a comprehensive solution for sanitizer quality assessment.

References

• U.S. Food and Drug Administration. ‘‘Direct Injection Gas Chromatography Mass Spectrometry Method for the Detection of Listed Impurities in Hand Sanitizers.’’
• Iwasa N. ‘‘Analysis of Impurities in Alcohol-Based Hand Sanitizers by GC-MS.’’ Shimadzu Application Note No. M315, March 2021.