ULTRA-LOW LEVEL ANALYSIS OF ALDOSTERONE IN PLASMA USING THE XEVO TQ-XS FOR CLINICAL RESEARCH

Importance of the Topic

Aldosterone quantification in plasma at ultra-low concentrations is crucial for research into cardiovascular and renal disorders. Reliable measurement supports clinical studies of mineralocorticoid balance and improves understanding of hormone regulation in health and disease.

Objectives and Study Overview

This study aimed to develop a high-sensitivity UPLC-MS/MS method using offline automated sample preparation to quantify aldosterone in human serum and plasma at sub-picomolar levels. The method was validated for linearity, precision, accuracy, carryover, and matrix effects to facilitate clinical research applications.

Methodology and Instrumentation

Sample preparation involved protein precipitation with zinc sulfate in methanol, followed by µElution cleanup on Oasis MAX plates using formic acid and ammonia in acetonitrile. The supernatant was diluted and injected into a Waters ACQUITY UPLC I-Class system with a CORTECS C18 column and VanGuard pre-column. Detection was performed on a Waters Xevo TQ-XS triple quadrupole mass spectrometer in negative electrospray ionization using multiple reaction monitoring. Sample handling was automated on a Tecan Freedom Evo 100 liquid handler.

Main Results and Discussion

• Calibration and Sensitivity: Calibration curves over 8–4162 pmol/L of aldosterone were linear (r² > 0.995). The method detected 3.3 pmol/L in plasma with signal-to-noise > 10.
• Precision: Total precision and repeatability at low (36 pmol/L), mid (286 pmol/L), and high (2932 pmol/L) concentrations were ≤ 6.3 % RSD.
• Carryover: No significant analyte carryover was observed after high concentration samples.
• Matrix Effects: Normalized matrix factors ranged 0.94–1.07 with average 1.01 and 5.2 % RSD, indicating robust internal standard compensation.
• Accuracy: External quality assessment (n = 15) showed mean method bias within ± 5.6 %, confirmed by Deming regression and Bland-Altman analysis.

Benefits and Practical Applications

The method provides high-throughput quantification of aldosterone from small sample volumes (200 µL), combining automation and µElution for efficient processing. It offers improved sensitivity and reliability for hormone profiling in clinical research studies and potential biomarker monitoring.

Future Trends and Potential Applications

Advancements may include further miniaturization of sample preparation, integration with high-resolution mass spectrometry for comprehensive steroid panels, and adaptation to point-of-care platforms. Emerging ionization techniques and microfluidic systems could enhance throughput and reduce cost.

Conclusion

A sensitive and precise UPLC-MS/MS method for aldosterone determination in plasma has been established, demonstrating excellent performance metrics suitable for clinical research. Automated sample handling and robust validation support its implementation for routine hormone analysis.

Reference

Foley D., Hammond G., Dugas B., Calton L.J. Ultra-Low Level Analysis of Aldosterone in Plasma Using the Xevo TQ-XS for Clinical Research. Waters Corporation, 2019.