Analysis of Residual Solvents in Pharmaceuticals - Report No. 338

Importance of the Topic

Ensuring the absence or controlled levels of residual organic solvents is a fundamental quality and safety requirement in pharmaceutical development and manufacturing. Headspace gas chromatography coupled with flame ionization detection (HS-GC-FID) provides a robust, sensitive, and reproducible approach for the quantification of volatile impurities in drug substances and formulations.

Objectives and Study Overview

This application note outlines a validated procedure for the simultaneous analysis of 24 target residual solvents in water-soluble pharmaceutical samples. The study follows guidelines from Japanese Pharmacopoeia (JP17 Supplement II) and United States Pharmacopeia (USP <467>). Key aims were to evaluate chromatographic separation, calibration linearity, detection limits, and total analysis time using Shimadzu’s Nexis™ GC-2030 system.

Methodology and Instrumentation

The analysis employed a Nexis™ GC-2030 gas chromatograph equipped with an HS-20 headspace unit and FID-2030 flame ionization detector. A 30 m × 0.32 mm I.D. SH-I-624Sil MS capillary column (1.8 μm film) was used. Nitrogen was the carrier gas under linear velocity control (35 cm/s). The GC oven program held at 40 °C for 20 min, ramped at 10 °C/min to 240 °C and held for 20 min (total run time 60 min). Headspace conditions included vial equilibration at 80 °C for 60 min under 75 kPa pressure.

• Injection mode: Split 1:5, injection volume 1.0 mL
• FID temperatures: detector 250 °C; H2 flow 32 mL/min; air flow 200 mL/min; makeup N2 flow 24 mL/min
• Headspace transfer line: 120 °C; sample line: 110 °C

Main Results and Discussion

The method achieved baseline separation of all 24 residual solvents, including aliphatic hydrocarbons, chlorinated solvents, ketones, and aromatics. Calibration curves exhibited excellent linearity (R2 > 0.999) across typical specification ranges. Limits of detection and quantification met pharmacopeial criteria. Repeatability and accuracy studies showed relative standard deviations below 5% and recoveries within 90–110%. Chromatograms demonstrated sharp, symmetric peaks with no significant coelution or matrix interference.

Benefits and Practical Applications

The described HS-GC-FID method offers:

• High sensitivity and specificity for a broad range of volatile organic solvents
• Compliance with JP and USP regulatory standards
• Reproducible quantitation suitable for routine quality control labs
• Streamlined sample preparation and minimal solvent consumption

Future Trends and Applications

Ongoing developments may include the use of faster, high-throughput columns, advanced detectors such as mass spectrometry for confirmatory analysis, and automated data processing driven by artificial intelligence. Integration with green analytical chemistry principles—reducing carrier gas usage and adopting eco-friendly reagents—will further enhance sustainability in pharmaceutical testing.

Conclusion

The Shimadzu Nexis™ GC-2030 with HS-20 headspace sampler and FID-2030 detector provides a reliable, fully validated platform for residual solvent analysis in pharmaceuticals. Its robust performance ensures regulatory compliance, quality assurance, and efficient laboratory workflow.

References

Shimadzu Application News G325 (JP, ENG), First Edition: Sep. 2022, ERAS-1000-0338