A validated LC-HRAM-MS method for the rapid and confident determination of azido (AZBT) impurity in sartan drug products

Importance of the topic

Angiotensin II receptor blockers also known as sartans are widely prescribed to manage hypertension. A mutagenic azidomethyl biphenyl tetrazole impurity (AZBT) can form during tetrazole ring synthesis and must be controlled at trace levels to meet toxicological concern thresholds and regulatory guidance.

Objectives and study overview

The study aimed to develop and validate a single high resolution LC MS method for quantifying AZBT in six marketed sartan drug products using Orbitrap Exploris 120 mass spectrometry coupled with an Accucore Biphenyl UHPLC column and a timed divert valve.

Methodology and used instrumentation

Sample preparation involved tablet grinding, dilution in methanol water diluent, sonication and centrifugation. Standards and spiking solutions covered LOD, LOQ and linearity ranges (0.025 to 40 ng/mL). Chromatography employed a Vanquish Flex binary UHPLC with Accucore Biphenyl 100 x 2.1 mm 2.6 μm column, mobile phases 0.1 formic acid in water and in methanol, gradient elution, 0.4 mL/min flow, column at 35 °C, divert valve engaged between 2.4 and 5.2 min to protect the MS. Mass spectrometry used OptaMax NG H ESI II probe in positive mode with targeted MS2 acquisition at 120 000 resolution, collision energy 5 V, internal calibration enabled.

Key findings and discussion

Limit of detection was established at 0.025 ng/mL (S:N > 25:1) and limit of quantitation at 0.25 ng/mL (S:N > 240:1). Linearity across 0.25 to 40 ng/mL yielded R2 of 0.9992 with deviations below 5.0 percent. Intra assay repeatability at standard limit (5 ng/mL) showed peak area RSD below 0.85 percent, cumulative RSD under 2.5 percent over 128 injections. Recovery ranged from 86 to 124 percent at low level, 92 to 113 percent at mid level, and 95 to 105 percent at high level. Chromatographic separation provided baseline resolution of AZBT from six sartan APIs enabling robust quantitation.

Benefits and practical applications

• One method for six different sartan products reduces method development time
• High resolution accurate mass separations eliminate potential matrix interferences
• Meets EDQM USFDA EMEA and ICH M7 guidelines for genotoxic impurity control
• Divert valve protects MS source and extends uptime
• Validated performance supports routine quality control and regulatory submissions

Future trends and applications

Emerging directions include extending HRAM MS workflows to additional genotoxic impurities in pharmaceutical substances developing automated sample preparation for higher throughput integrating advanced data processing algorithms for real time impurity surveillance and harmonizing global regulatory limits across product portfolios.

Conclusion

The validated LC HRAM MS method using Orbitrap Exploris 120 and Accucore Biphenyl UHPLC provides rapid sensitive and selective quantitation of AZBT impurity in six sartan drug products. The approach delivers excellent linearity reproducibility and recovery while complying with international regulatory requirements and is ideally suited for routine QC laboratories.

References

1. Risk of the presence of mutagenic azido impurities in losartan active substance EDQM
2. Guidance for Industry Q2B Validation of Analytical Procedures Methodology USFDA November 1996
3. ICH Topic Q2(R1) Validation of analytical procedures text and methodology June 1995
4. ICH M7(R1) Assessment and control of DNA reactive mutagenic impurities in pharmaceuticals to limit potential carcinogenic risk M7 Step 4 version 31 March 2017
5. Taiwan FDA method determination of AZBT in sartan drug substances July 2021
6. LGL LC MS MS method for AZBT determination in valsartan irbesartan candesartan and losartan EDQM document
7. Swissmedic Test method 31 PV 185 for genotoxic substances in sartans July 2021
8. Jires J et al determination of azidomethyl biphenyl tetrazole analogues in sartan APIs Journal of Pharmaceutical and Biomedical Analysis 2021 205 114300