Analytical Workflow for Extractable and Leachable Impurities

Importance of the Topic

Extractable and leachable (E&L) testing is critical in pharmaceutical manufacturing to ensure patient safety and drug efficacy. Trace contaminants from packaging, delivery systems, or processing equipment can migrate into drug formulations under normal use conditions and pose toxicity risks or affect potency. A robust analytical workflow is essential for identifying and quantifying these impurities at sensitive levels.

Objectives and Study Overview

This work presents a comprehensive E&L testing strategy illustrated by a case study on pharmaceutical-grade O-rings. Key goals include:

• Risk assessment and selection of materials for testing.
• Determination of analytical evaluation thresholds (AET).
• Extraction under accelerated conditions (40 °C, 30 days) using multiple solvents (water, saline, ethanol gradients, surfactants, acids, bases).
• Application of orthogonal analytical techniques to capture volatile, semi-volatile, non-volatile, and elemental impurities.

Methodology and Instrumentation

Sample preparation and analytical platforms comprised:

• Accelerated solvent extraction and solvent conditioning with water, 5 M NaCl, 50 %/100 % ethanol, surfactant and pH adjustments.
• Gas chromatography–Orbitrap MS: Thermo Scientific Trace 1310 GC coupled to Q Exactive GC for EI/CI full-scan high-resolution analysis (up to 120 000 FWHM, <1 ppm mass accuracy).
• Liquid chromatography–Orbitrap MS: UltiMate 3000 UHPLC with Q Exactive Plus MS/MS, polarity switching, data-dependent MS2 at 17 500–70 000 resolution.
• Inductively coupled plasma MS: iCAP Q ICP-MS with KED helium cell for elemental impurity screening (sub-ppt detection, nine orders of dynamic range).
• Data processing software: TraceFinder for deconvolution and targeted screening, Compound Discoverer for unknown elucidation, SIEVE for differential analysis, supported by NIST, mzCloud, in-house and E&L spectral libraries.

Key Results and Discussion

Semi-volatile analysis via GC-MS enabled automated peak deconvolution and library matching, with high-resolution filtering (HRF) scores > 99 % for confident identification of extractables such as Irganox antioxidants, phthalates, amides, and unknown substituted phenolics. LC-MS workflows provided rapid MS1 and MS2 data for non-volatile components, confirming identities through accurate mass and fragmentation. Elemental screening showed most metals below detection or in low ng·mL⁻¹ levels; QC drift checks remained within ±5 % RSD over extended runs.

Benefits and Practical Applications

This integrated E&L workflow delivers:

• High confidence identification of both known and unexpected impurities.
• Streamlined data processing through automated software pipelines.
• Regulatory compliance support via USP 1663/1664, ICH Q3D and BPOG guidelines.
• Reproducible performance for routine QA/QC in drug development and manufacturing.

Future Trends and Potential Applications

Emerging directions include expanding high-resolution spectral libraries (mzCloud, E&L databases), enhanced unknown identification algorithms, integration of machine learning for pattern recognition, and adoption of standardized protocols across single-use systems. Continuous improvements in MS instrumentation and software will further reduce analysis time and improve detection limits.

Conclusion

A robust E&L analytical workflow combining GC-Orbitrap, LC-Orbitrap, and ICP-MS with advanced data analysis enables comprehensive screening of extractable and leachable impurities. This approach ensures patient safety, regulatory compliance, and drug quality in pharmaceutical applications.