Analysis of Elemental Impurities in Synthetic Oligonucleotides by ICP-MS

Importance of the Topic

Molecule-based therapeutics built on synthetic oligonucleotides offer targeted approaches to treat a growing array of diseases including cancer neurological and metabolic disorders
Ensuring these products meet regulatory purity standards for metallic contaminants is critical to patient safety and drug efficacy
Analytical methods that reliably quantify elemental impurities in complex biomolecules support quality control and regulatory compliance

Study Objectives and Overview

Develop and validate an ICP MS protocol using the Agilent 7850 for measuring 24 elemental impurities in synthetic antisense oligonucleotides
Align method performance with ICH Q3D Q2 and USP chapters 232 233 guidelines for permissible daily exposure limits and analytical validation
Evaluate method parameters including specificity sensitivity accuracy precision and robustness under routine laboratory conditions

Methodology and Instrumentation

Sample prep involved dissolving 0.1g oligonucleotide at 10mg/mL into 50g of diluent containing 3 percent HNO3 and 1 percent HCl to yield a 500 fold dilution
Calibration and quality control solutions spiked at targeted J values corresponding to parenteral limits with levels at 0.5J 0.8J 1J and 1.5J
Instrument Agilent 7850 ICP MS with ORS4 collision cell in helium kinetic energy discrimination mode
Standard sample introduction comprising MicroMist nebulizer quartz spray chamber quartz torch nickel cones and automation via I AS autosampler
Preset ICH USP method in MassHunter software provided optimized RF power gas flows cell settings and calibration templates

Main Results and Discussion

System suitability exhibited drift within ±5 percent over a 7 hour run and long term QC stability with RSD below 2.6 percent across all elements
Limit procedure confirmed detectability with 0.8J spikes below 1J standard and recoveries within defined criteria
Quantitative accuracy demonstrated spike recoveries between 85 and 115 percent at 0.5J 1J and 1.5J levels
Precision tests yielded repeatability and intermediate precision RSDs below 4 percent meeting USP requirements
Calibration curves showed excellent linearity with correlation coefficients above 0.999 and detection limits in the low ppt range

Benefits and Practical Applications

The validated method supports high throughput routine analysis of oligonucleotide therapeutics
Single cell mode helium KED and preset software workflows simplify operation for laboratories new to ICP MS
Robust performance ensures compliance with regulatory standards improving product safety and accelerating development timelines

Future Trends and Applications

Expansion of elemental impurity guidelines tailored for oligonucleotide modalities expected from ICH USP and regulatory agencies
Integration with automated sample handling and real time data analytics for continuous manufacturing quality control
Application of collision cell technologies to enable analysis of emerging modalities such as larger nucleic acid constructs and conjugates

Conclusion

The Agilent 7850 ICP MS method meets rigorous ICH USP criteria for elemental impurity analysis in synthetic oligonucleotides
It delivers reliable specificity sensitivity precision accuracy and robustness for parenteral dose limits
Preset methods and automated tuning streamline deployment ensuring consistent lab to lab implementation

References

• Kiesman WF et al Perspectives on the Designation of Oligonucleotide Starting Materials Nucleic Acid Therapeutics 2021 31 2 93 113
• ICH Q3D R2 Guideline for Elemental Impurities Step 4 International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use 2022
• USP Elemental Impurities Limits Chapter 232 and Procedures Chapter 233 Pharm Forum 2014 2016
• Sapru M CMC Regulatory Considerations for Oligonucleotide Drug Products FDA Perspective PQRI USP Workshop 2017