Active drug substance impurity profiling part II. LC/MS/MS fingerprinting

Area of Science:

• Analytical Chemistry
• Pharmaceutical Analysis
• Mass Spectrometry

Background:

• High-Performance Liquid Chromatography (HPLC) is standard for monitoring drug substance impurities.
• Variable retention times in HPLC can cause ambiguity in impurity identification.
• Characterizing impurities online is crucial when impurity standards are unavailable.

Purpose of the Study:

• To evaluate Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC/MS/MS) for generating characteristic impurity fingerprints.
• To assess the reproducibility of these fingerprints across different batches of a drug substance.
• To explore the utility of MS/MS fingerprinting for distinguishing isomers and assigning tentative structures.

Main Methods:

• Generated MS/MS fingerprints (precursor ion mass + ≥3 product ion masses) for a drug substance (DuP 941) and its impurities using standards.
• Optimized collision cell parameters, identifying collision energy as critical for reproducible fingerprint generation.
• Performed online MS/MS fingerprinting for seven impurities in an early drug substance lot and compared them to subsequent lots.

Main Results:

• Reproducible MS/MS impurity fingerprints were generated, with high consistency observed across different drug substance lots, even for impurities at 0.01 UV area percent.
• MS/MS fingerprinting successfully differentiated between two known positional isomers.
• The method facilitated the tentative structural assignment of drug impurities.

Conclusions:

• LC/MS/MS provides a robust method for generating reproducible impurity fingerprints in drug substances.
• This technique is valuable for online impurity characterization, isomer differentiation, and structural elucidation, especially when standards are lacking.
• MS/MS fingerprinting enhances the reliability of impurity monitoring in pharmaceutical development and quality control.