NDSRI Analysis: Is Sensitivity Really the Biggest Challenge—or Is It Sample Preparation?
An interesting 2026 paper in BMC Chemistry reports an LC–TQ–MS/MS method for trace-level determination of two levofloxacin-associated NDSRIs: N-nitroso methyl piperazine (N-NMP) and N-nitroso desmethyl levofloxacin (N-NDLOX).
What caught my attention was not simply the low LOQs of 0.6 and 1.0 ng/mL, but the overall analytical strategy.
The authors achieved >98% extraction using a relatively simple 0.1% formic acid/acetonitrile system with 15-minute sonication, while tablet recoveries remained approximately 93–100%. Matrix evaluation also showed a solvent-to-matrix calibration slope ratio of 0.94, suggesting limited ion suppression/enhancement.
More importantly, the study connects:
Analytical Target Profile / ICH Q14
LC–TQ–MS/MS method development
Finished-product matrix assessment
(Q)-SAR and CPCA-based risk assessment
Green/White Analytical Chemistry principles
This raises some interesting questions for those working on pharmaceutical nitrosamines:
- When NDSRI recovery is poor in finished dosage forms, should our first focus be MS sensitivity—or extraction chemistry and analyte–excipient interactions?
- Is comparison of solvent and matrix calibration slopes sufficient to establish matrix-effect control, or should isotope-labelled internal standards, matrix factors and/or post-column infusion become routine expectations for NDSRI LC–MS methods?
- How transferable is a successful extraction procedure from one formulation to another when NDSRIs can have substantially different physicochemical behaviour?
- As regulatory expectations evolve, should “method sustainability” become part of the Analytical Target Profile alongside sensitivity, specificity, accuracy and precision?
For me, the key takeaway is that the next generation of NDSRI methods should not be judged on LOQ alone. Recovery robustness, matrix understanding, toxicological relevance and routine laboratory practicality need to be considered together.
Interested to hear the experience of colleagues working on NDSRI method development, recovery problems and LC–MS/MS validation in finished pharmaceutical products.