Quantitative Analysis of Azido Impurities in Five Sartan Drug Substances using a Triple Quadrupole Mass Spectrometer

Importance of the Topic

Azido impurities in sartan drug substances pose a potential carcinogenic risk and must be controlled below the Threshold of Toxicological Concern. Reliable quantification of these impurities is essential for patient safety and regulatory compliance in pharmaceutical manufacturing.

Objectives and Study Overview

This study aimed to develop and validate a single liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for simultaneous quantitation of two azido impurities, AZBT and AMBBT, in five commonly used sartan drugs: olmesartan, losartan, irbesartan, valsartan, and candesartan.

Methodology and Instrumentation

A Shimadzu LCMS-8060 system equipped with an SPD-M40 photodiode array detector was used.

• Column: Shim-pack Velox SP-C18, enabling full separation in 8.5 minutes.
• Divert Valve Program: Directed only the azido impurities into the mass spectrometer to protect the detector from high drug loads.
• Detection: Multiple reaction monitoring (MRM) for AZBT and AMBBT quantitation.

Main Results and Discussion

Chromatographic separation achieved baseline resolution of the five sartans and both azido impurities within 8.5 minutes. System suitability tests showed retention time and peak area %RSDs below 3%.

• LOD and LOQ: Both impurities exhibited LOD of 0.005 ng/mL (S/N >6) and LOQ of 0.01 ng/mL (S/N >15).
• Linearity: Calibration curves over four orders of magnitude yielded R2>0.999 (AZBT: 0.01–500 ng/mL; AMBBT: 0.01–200 ng/mL).
• Recovery: Spike-recovery experiments at multiple levels demonstrated recoveries within 70–130% for both impurities across all drug matrices.

Benefits and Practical Applications

This method delivers rapid and sensitive detection of trace azido impurities, ensuring quality control of sartan pharmaceuticals. The streamlined workflow minimizes instrument contamination and supports regulatory requirements for impurity limits.

Future Trends and Opportunities

Advancements may include high-resolution mass spectrometry for increased specificity, automated sample preparation to improve throughput, and expanded application to other drug classes with similar impurity concerns. Integration with real-time monitoring could further enhance process analytical technology in pharmaceutical manufacturing.

Conclusion

A robust LC–MS/MS method using Shimadzu LCMS-8060 achieved full separation, high sensitivity, and excellent reproducibility for quantifying AZBT and AMBBT in five sartan substances. The approach meets stringent regulatory limits and offers a practical solution for routine quality assurance in drug production.