Workflow Overview for Drug Impurities Analysis
Impurities in products often represent minor components, and the ability to detect these in the presence of significant product is a challenge. Once detected, the need to assign a structure to the impurity or degradantis the next challenge. Both of these challenges are aided by Orbitrap™ technology. The high sensitivity and wide dynamic range of the Thermo Scientific Orbitrap Elite MS means that even minor components can be detected and valuable data gathered, while MSn fragmentation aids in structure determination.
Comstock K, Stratton T, et al.
ASMS 2012 Poster
Sample Preparation Workflow for Drug Impurities Analysis
The detection of degradation products or impurities in a finished product requires that a representative sample of the product be prepared that reflects any and all impurities or degradants that might be present. The finished product or its constituent parts are not the target of the study; instead, the potentially very minor impurities and degradants are. Extraction/solvation of a powder or liquid product, either with a solvent suitable for (U)HPLC analysis or extraction with dilution to a suitable solvent, is a common basic approach.
Degradation studies, which are often performed through exposure of the material to elevated temperature, humidity, pH, ultraviolet light, and other stresses, provide an early indication of potential impurities that may arise over time.
Mass Spectrometry Workflow for Drug Impurities Analysis
Detection requirements for impurities and degradants are often very low (typically 0.1% for pharmaceutical agents). This level of detection is required in the presence of often overwhelming amounts of the desired product. Chromatographic separation prior to introduction to the mass spectrometer is important to assure that the impurities can be observed.
The sensitivity and wide dynamic range of Orbitrap™-based mass spectrometers allows for both the detection of, and the acquisition of fragmentation data on, these minor components. In addition, the fast scanning speed of the Thermo Scientific Q Exactive and Orbitrap Elite instruments allows for screening injections, where valuable fragmentation data is acquired on multiple components. Combined with the very high resolution and robust mass accuracy of Orbitrap mass spectrometers, the data gathered allows for the potentially related impurities and degradantsto be found in the sample. Re-acquisition using a targeted MSn fragmentation approach can be performed on peaks discovered through fragmentation searching. These structure identification injections can use a combination of CID and HCD fragmentation techniques on hybrid Orbitrap instruments, like the Thermo Scientific LTQ Orbitrap XL, Orbitrap Velos Pro, and Orbitrap Elite systems, to provide significant structure interpretation power.
Data Analysis Workflow for Drug Impurities Analysis
Processing data obtained during impurities analysis and degradation studies can proceed through two major routes. For degradation products and impurities related to the product structure, a fragmentation-based search (Thermo Scientific Mass Frontier software version 7.0) can be utilized. This approach makes use of the fast scanning HCD MS2 data gathered on multiple precursors to identify potentially related materials for study.
For more complex products, where impurities may not be related to components of the product or degradants may arise from one or multiple components, a differential analysis approach is useful. The new lot or degradation sample is compared to a control analysis to detect small variation, which may be the result of impurities or degradants.
For either approach, the combination of high mass accuracy, high resolution, and accurate-mass MS/MS and MSn fragmentation provided by Orbitrap™ mass spectrometers enables identification through fragmentation analysis and library searching.
Here we show the detection of multiple trace impurities and degradation products in an active pharmaceutical ingredients (API) sample preparation through fragmentation analysis to detect related compounds and identify them, even those coeluting with the significant API peak.
Orbitrap of Choice for Drug Impurities Analysis
The main challenges of impurities and degradant analysis, the detection of minor components and their subsequent identification, are both met by Orbitrap™-based mass spectrometers. Fast, high-resolution, full-scan, accurate-mass data obtained is useful for differential analysis. Accurate mass MS/MS and MSn data aids in both the detection and identification of impurities and degradants. The Thermo Scientific Q Exactive MS, with its fast scan speed and high resolving power, is a good choice for differential analysis and library searching approaches. The ability to acquire MSn fragmentation with multiple techniques at high resolution and mass accuracy makes the hybrid instruments like the Thermo Scientific LTQ Orbitrap XL, Orbitrap Velos Pro, and Orbitrap Elite instruments ideal for more complex identifications.
Orbitrap of Choice: The Orbitrap Velos Pro™ MS
- The Orbitrap Velos Pro hybrid ion trap-mass spectrometer provides the high resolving power (up to 100,000 at m/z 400) with good sensitivity and dynamic range in full-scan MS for analysis of complex samples.
- Fast, high-quality MS and MSn scans allow maximal identification of compounds in a complex matrix.
- Complementary fragmentation techniques, including collision-induced dissociation (CID) and higher-energy collisional dissociation (HCD), provide fragment information for confident identification of structure.