AN EFFICIENT METHOD FOR THE DETERMINATION OF TRACE EXCIPIENT IMPURITIES IN BIOTHERAPEUTIC DRUG PRODUCTS CONTAINING POLYSORBATE

Significance of the Topic

The stability and purity of polysorbate-80 (PS-80) in biotherapeutics are critical for ensuring drug efficacy and patient safety. Trace degradants such as free oleic acid, generated by residual esterases, can compromise product performance and introduce safety risks. A rapid, sensitive analytical assay is therefore essential to monitor PS-80 integrity throughout the drug lifecycle.

Aims and Study Overview

This study aimed to develop and validate a high-throughput, UV-based UPLC method for the quantitation of trace oleic acid impurities in biotherapeutic formulations containing PS-80. The focus was on achieving low detection limits, broad dynamic range, and minimal sample preparation compatible with regulated environments.

Methodology and Instrumentation

The assay employed an ACQUITY UPLC H-Class Bio System equipped with a tunable UV detector (TUV) and a 5-mm titanium flow cell, operating at 200 nm. Separation was achieved on an ACQUITY UPLC Protein BEH C4 column (300 Å, 1.7 μm, 2.1 × 100 mm) under isocratic conditions (65 % MeCN/0.1 % formic acid) at 0.2 mL/min and 30 °C. Sample preparation used a low-volume liquid–liquid extraction (LLE) with MeCN/H2O and cis-10-nonadecenoic acid as an internal standard. Calibration was established over a dynamic range of 0.000024 % to 0.1 % oleic acid (0.24 ppm to 1000 ppm), with both multi-point and single-point approaches evaluated.

Main Results and Discussion

The method demonstrated linearity across five orders of magnitude with correlation coefficients exceeding 0.9998. UV-based quantitation achieved a practical limit of quantitation around 60 ppb (confirmed by MS SIR). Recoveries for oleic acid ranged from 90 % to 98 % with relative standard deviations below 4 %. Carry-over was negligible, and baseline separation between oleic acid and the internal standard minimized interference. Application to infliximab (PS-80) and trastuzumab (PS-20) formulations confirmed assay specificity: free oleic acid was detected only in hydrolyzed PS-80 samples (<1 % relative to the internal standard), whereas PS-20 samples showed no signal.

Benefits and Practical Applications

• Rapid 5-minute analysis time enhances throughput.
• High sensitivity suitable for trace-level monitoring.
• Minimal sample preparation reduces labor and variability.
• Single-point calibration simplifies routine quantitation.

Future Trends and Opportunities

As analytical demands grow, integration of this UPLC-UV workflow with automated sample handling and orthogonal MS detection will further enhance sensitivity and selectivity. Expansion to other fatty acid impurities and surfactant systems can broaden its application in pharmaceutical QA/QC. Implementation within continuous manufacturing and real-time release testing frameworks represents a logical next step.

Conclusion

The presented UPLC-UV method provides a robust, sensitive, and high-throughput solution for monitoring oleic acid impurities in PS-80-containing biotherapeutics. Its simplicity and compatibility with regulated environments make it a valuable tool for ensuring product quality and safety.

References

• Birdsall R., Yu YQ. An Efficient UV-based method for the assessment of Oleic acid content in biotherapeutic drug products containing Polysorbate-80. Waters Application Note. 2017. 720006129EN.