Packed Column Analysis of Alcohol Number Determination Conforming to Japanese Pharmacopoeia Using Nexis™ GC-2030 (FID)

Significance of the Topic

Determining the alcohol number of ethanol-containing preparations is a critical quality control measure in pharmaceutical manufacturing and disinfection product testing. The Japanese Pharmacopoeia (JP) defines both distillation and gas chromatographic procedures to ensure accurate, reproducible measurement of ethanol content. Implementing a robust packed-column gas chromatography method enhances laboratory efficiency and compliance with regulatory standards.

Objectives and Overview of the Study

This application note illustrates the procedure for alcohol number determination as stipulated by the JP using the Shimadzu Nexis GC-2030 gas chromatograph. Key aims include:

• Demonstrating compatibility of the Nexis GC-2030 with packed silica columns for ethanol analysis.
• Verifying method performance in terms of resolution, repeatability, and accuracy.
• Highlighting the versatility of a single instrument to handle both packed and capillary column methods for ethanol purity and alcohol number testing.

Methodology and Instrumentation

Sample Preparation:

• Dilute a sample volume equivalent to 5 mL ethanol to 50 mL with water.
• Add 10 mL of aqueous acetonitrile internal standard solution to 25 mL of the diluted sample, then dilute to 100 mL.
• Prepare the standard solution similarly by diluting 5 mL ethanol to 50 mL, adding internal standard, and adjusting to 100 mL.
• Equilibrate sample and standard vials in water at room temperature for 1 hour; inject 1.0 mL of headspace or direct liquid sample.

Instrumentation Configuration:

• Gas Chromatograph: Shimadzu Nexis GC-2030 with SINJ-2030 injector and FID-2030Packed kit.
• Injection Mode/Volume: Direct injection of 1.0 mL at 110 °C.
• Carrier Gas: Nitrogen at ~35 mL/min (adjusted to achieve 5–10 min ethanol retention).
• Column: Porapak™ Q packed column, 1.5 m × 3 mm I.D., 80/100 mesh, operated at 110 °C.
• Detector: Flame Ionization Detector at 150 °C (H₂ 32 mL/min, air 200 mL/min, makeup gas 5 mL/min).

Main Results and Discussion

Standard Solution Performance:

• Chromatographic resolution between ethanol and acetonitrile achieved at 2.56, exceeding the JP requirement of ≥2.0.
• Five replicate measurements of the ethanol/internal standard peak-height ratio (Qs) yielded an average of 1.149 with negligible variation, demonstrating excellent repeatability.

Sample Analysis:

• Overlaid chromatograms for test samples at nominal ethanol concentrations of 60 %, 70 %, and 80 % (vol/vol) showed well-resolved peaks of similar intensity, reflecting consistent sample loading per JP instructions.
• Calculated alcohol numbers were 6.51, 7.59, and 8.59 for the 60 %, 70 %, and 80 % samples, respectively, in close agreement with theoretical values.

The Nexis GC-2030’s ability to switch between packed and capillary column configurations by means of the FID-2030Packed kit simplifies laboratory workflows, enabling both alcohol number determination and ethanol purity testing with one instrument.

Benefits and Practical Applications

The described method offers:

• Regulatory compliance with the Japanese Pharmacopoeia requirements for alcohol number testing.
• Time and space savings by consolidating multiple analyses on a single GC platform.
• High reproducibility and resolution, supporting reliable quality control in pharmaceutical and disinfectant production.

Future Trends and Applications

Emerging developments likely to influence alcohol number analysis include:

• Advances in packed column chemistries for faster separation and enhanced robustness.
• Integration of headspace autosamplers for improved throughput and sample handling.
• Use of alternative detectors or dual-detection systems to broaden analyte scope.
• Adoption of microfluidic or portable GC systems for on-site monitoring of disinfection ethanol content.
• Automated data processing and machine learning algorithms to accelerate result interpretation and reporting.

Conclusion

The Shimadzu Nexis GC-2030, equipped with a packed-column support kit, provides a streamlined, accurate approach to alcohol number determination in accordance with the Japanese Pharmacopoeia. Its dual-capacity for packed and capillary column analyses optimizes laboratory efficiency, reduces equipment redundancy, and maintains high analytical performance for ethanol-based pharmaceuticals and disinfectants.

References

• Japanese Pharmacopoeia, General Tests, Processes and Apparatus, 1.01 Alcohol Number Determination.