Ultra-fast LCMS analysis of Antiarrhythmic drugs in plasma

Significance of the Topic

High‐throughput quantitation of drugs in plasma by liquid chromatography–tandem mass spectrometry (LC-MS/MS) is essential for therapeutic drug monitoring, pharmacokinetic studies, and toxicology. Antiarrhythmic agents require precise measurement because of narrow therapeutic windows and interpatient variability. An ultra-fast LC-MS/MS workflow can greatly increase sample throughput and laboratory efficiency.

Objectives and Study Overview

This study presents a novel LC-MS/MS configuration for rapid and accurate quantitation of five antiarrhythmic drugs and their main active metabolite in spiked human plasma. Key aims included:

• Developing an analytical cycle time under 50 seconds.
• Evaluating isocratic and gradient elution modes for separation and performance.
• Assessing linearity, accuracy, precision, and column durability over thousands of injections.

Analytical Methodology

Sample preparation involved a simple protein precipitation of 100 µL plasma with acetonitrile/formic acid containing deuterated internal standard, followed by dilution and centrifugation. A 1 µL aliquot was injected onto a biphenyl guard column.

• Mobile phases: water with 0.1% formic acid (A) and acetonitrile:methanol 50:50 with 0.1% formic acid (B).
• Flow rate: 1,000 µL/min.
• Injection cycle time: <7 seconds (autosampler rinse and refill).
• Elution modes: isocratic (40% B) for <25 s total cycle and gradient (5%→95% B in 25 s) for <50 s cycle.
• Detection: Multiple reaction monitoring (MRM) in positive electrospray ionization.

Instrumentation Used

The following instruments were employed:

• Nexera XR UHPLC system coupled to an LCMS-8050 triple-quadrupole MS.
• SIL-40C XR autosampler configured for ultrafast injection cycles.
• Shim-pack Velox EXP guard column Biphenyl (5.0 × 3.0 mm, 2.7 µm).

Main Results and Discussion

Both isocratic and gradient methods met CLSI C62-A guidelines for linearity (r ≥ 0.997), accuracy (89–114%), and precision (intra- and inter-day RSD ≤13%).

• Calibration ranges spanned 0.5–1,000 µg/L across compounds.
• Carry‐over was negligible (<0.2% of LOQ).
• Gradient elution improved separation of Atenolol and Metoprolol and reduced matrix ion suppression, while isocratic mode achieved cycle times under 25 s for select analytes.
• Column performance remained stable over 2,300 injections, with retention time RSD ≤0.7% and peak width RSD ≤8%.

Benefits and Practical Applications

The method offers:

• Sample‐to‐sample throughput in tens of seconds, enabling hundreds of analyses per day.
• Robust quantitation of antiarrhythmic drugs for clinical pharmacology, therapeutic drug monitoring, and toxicology screening.
• Reduced solvent consumption and minimal carry‐over, lowering operating costs and maintenance.

Future Trends and Potential Applications

Potential developments include:

• Expansion to broader drug panels and metabolites.
• Integration with high‐resolution MS or ion mobility for enhanced selectivity.
• Automated sample preparation and data processing using machine learning.
• Miniaturized or multiplexed LC platforms for point‐of‐care or field applications.

Conclusion

This work demonstrates a proof-of-concept for ultra-fast LC-MS/MS quantitation of antiarrhythmic drugs in plasma with cycle times below 50 seconds, robust analytical performance, and long column lifetime. The approach can significantly improve laboratory throughput and support diverse applications in clinical and pharmaceutical analysis.

References

• CLSI C62-A Liquid Chromatography–Mass Spectrometry Methods; Approved Guidelines.