A Qualified Method for Quantification of Reserpine in Protein-Precipitated Human Plasma Using Xevo G2-S Time-of-Flight Mass Spectrometr

Significance of the topic

Reliable quantification of trace-level drug compounds in biological matrices is crucial for drug discovery and development.
High-resolution time-of-flight mass spectrometry (QTof) can deliver both qualitative and quantitative data in a single assay, streamlining workflows in DMPK laboratories.

Objectives and study overview

The primary aim was to establish and qualify a generic LC/MS method for accurate measurement of reserpine in protein-precipitated human plasma using the Xevo G2-S QTof.
The study spanned three consecutive days to assess method precision, accuracy, sensitivity, and linear dynamic range.

Methodology and instrumentation

Sample preparation involved protein precipitation of human plasma with acetonitrile (3:1 v/v), centrifugation, and dilution prior to injection.
A nine-minute gradient on an ACQUITY UPLC I-Class System with a C18 column (2.1 x 100 mm, 1.7 µm) separated analytes at 600 µL/min.
The Xevo G2-S QTof operated in MS scan mode with Leucine encephalin as LockSpray reference; data were acquired in continuum mode and processed with MassLynx and TargetLynx.

Main results and discussion

Reserpine eluted at 5.85 minutes, yielding a sharp peak (1.3 s at half height).
The lower limit of quantification (LLOQ) was 0.049 ng/mL (S/N > 10), and the limit of detection was ≤ 0.024 ng/mL.
Calibration was linear over three orders of magnitude (0.049–100 ng/mL) with correlation coefficients (r²) ≥ 0.9989 across three days.
Intra-day and inter-day bias values fell within ±15%, and precision (%CV) ranged below 10% for standards and quality controls.

Benefits and practical applications

This generic LC/MS-QTof method enables simultaneous detection of parent drugs and metabolites without the need for compound-specific MRM optimization.
A single 10-minute assay accommodates a wide polarity range, supporting high-throughput DMPK screening and metabolite identification in early discovery and development phases.

Future trends and possibilities

Advances in high-resolution MS detectors and ion-transport technologies will further improve sensitivity and dynamic range.
Integration of QTof data with automated metabolite profiling and machine-learning algorithms may accelerate bioanalytical workflows.
Multiplexed assays and real-time quantification are emerging applications in both preclinical and clinical settings.

Conclusion

A qualified, robust, and sensitive LC/MS method using Xevo G2-S QTof MS has been demonstrated for quantifying reserpine in human plasma.
The approach meets stringent bioanalytical criteria, offering a versatile tool for DMPK laboratories to combine qualitative and quantitative screening in a unified workflow.