Analysis of Residual Solvents in drug products using Nexis GC-2030 combined with HS-20 head space

Significance of the Topic

Residual solvents in pharmaceuticals are volatile organic compounds that can pose health risks if not properly controlled. Regulatory authorities such as the USP classify these solvents into Classes 1–3 and set strict limits. Reliable, sensitive, and reproducible analysis of residual solvents ensures product quality, patient safety, and compliance with global pharmacopeial standards.

Objectives and Study Overview

This work demonstrates the application of Shimadzu’s HS-20 headspace sampler coupled to the Nexis GC-2030 gas chromatograph for the determination of residual solvents in water-soluble drug products. The study aims to validate the USP <467> Procedure A method for both Class 1 and Class 2 solvent mixtures, focusing on sensitivity, separation efficiency, and repeatability.

Methodology and Instrumentation

The analysis follows USP <467> Procedure A using headspace gas chromatography. Key analytical conditions are:

• Gas Chromatograph: Shimadzu Nexis GC-2030 with FID-2030
• Headspace Sampler: Shimadzu HS-20
• Column: SH-Rxi-624SilMS, 30 m × 0.32 mm I.D., 1.8 µm film
• GC Oven Program: 40 °C (20 min) → 10 °C/min → 240 °C (20 min), total 60 min
• Injection Mode: Split 1:5, 1 mL injection
• Carrier Gas: Helium, constant linear velocity 35 cm/s
• FID Conditions: 250 °C, H₂ 40 mL/min, Air 400 mL/min, Make-up He 30 mL/min
• Headspace Settings: Oven 80 °C, Sample Line 110 °C, Transfer Line 120 °C, vial pressurization 75 kPa, equilibration 60 min

Key Results and Discussion

Class 1 Solvents
The Class 1 standard mixture achieved signal-to-noise (S/N) ratios well above USP requirements. For 1,1,1-trichloroethane the S/N was 220 (required ≥5), and even the least sensitive compound, carbon tetrachloride, reached an S/N of 20. Repeatability of peak areas (n=6) yielded RSDs between 2.3% and 3.4%.

Class 2 Solvents
The Class 2 solvent mixture was split into A and B to optimize resolution. Using the low-bleed SH-Rxi-624SilMS column, critical pairs such as acetonitrile/methylene chloride achieved a resolution of 2.4 (required ≥1.0). All 30 Class 2 compounds were baseline-separated with sharp, symmetrical peaks, demonstrating the method’s robustness for complex mixtures.

Benefits and Practical Applications

• High sensitivity and low detection limits for trace solvents.
• Excellent repeatability and robustness across multiple injections.
• Full compliance with USP <467> standards for residual solvent analysis.
• Wide applicability in quality control laboratories of pharmaceutical companies.

Future Trends and Applications

Advances may include faster GC ramps, multidimensional chromatography for even more complex matrices, automated sample preparation, and integration with data analytics for real-time compliance monitoring. Miniaturized or portable headspace-GC systems could further streamline on-site testing.

Conclusion

The Shimadzu HS-20 headspace sampler combined with the Nexis GC-2030 delivers a validated, high-performance solution for USP <467> residual solvent analysis. Its sensitivity, resolution, and precision make it a reliable tool for pharmaceutical QC, ensuring product safety and regulatory compliance.

References

• Shimadzu Application News No. G290, June 2017