Assessing stability-indicating methods for coelution by two-dimensional liquid chromatography with mass spectrometric...

Area of Science:

• Analytical Chemistry
• Chromatography
• Pharmaceutical Analysis

Background:

• Trace organic impurities and degradants often coelute with active pharmaceutical ingredients (APIs).
• Similar structures and varying concentration levels complicate impurity detection.
• Conventional detectors (e.g., diode array, mass spectrometry) may fail to identify residual coeluting impurities, leading to false negatives.

Purpose of the Study:

• To present the application of two-dimensional chromatography (2D-LC) for addressing coelution issues in conventional chromatography.
• To evaluate the use of similar and complementary column phases in 2D-LC for impurity profiling.
• To demonstrate the utility of 2D-LC as a method assessment tool in pharmaceutical and related industries.

Main Methods:

• Pseudocomprehensive two-dimensional liquid chromatography (2D-LC) was employed, transferring regions of interest to a secondary column for further separation.
• Investigated the use of identical stationary phases in both dimensions for resolving coeluting impurities.
• Explored the use of complementary phases in both dimensions.
• Utilized conventional detectors for monitoring coelution in the remaining chromatogram.
• Confirmed results using mass spectrometry.

Main Results:

• The use of the same phase in both dimensions proved effective for resolving coeluting impurities, particularly those near the main component with large differences in concentration.
• This approach simplifies method development compared to finding complementary columns, as hydrophobicity often dominates reversed-phase separations.
• Separation was feasible when impurity and API levels in transferred fractions were comparable.
• Mass spectrometry confirmed the impurity identifications.

Conclusions:

• Two-dimensional chromatography, especially using identical phases, is a powerful technique for overcoming coelution challenges in pharmaceutical impurity analysis.
• This method enhances the detection and identification of trace organic impurities that are missed by conventional techniques.
• 2D-LC serves as a valuable method assessment tool, improving the reliability of pharmaceutical analysis.