LC-MS/MS Method for the Determination of HCTZ and Losartan from Human Plasma Using SOLA CX

Importance of the Topic

Human plasma analysis of antihypertensive drugs is critical for therapeutic monitoring and pharmacokinetic studies. Rapid and reliable quantification of hydrochlorothiazide (HCTZ) and losartan at trace levels supports clinical decision-making and drug development. Advances in solid phase extraction (SPE) and high-efficiency chromatography enhance throughput and data quality in bioanalytical laboratories.

Study Objectives and Overview

This study presents a streamlined LC-MS/MS workflow employing Thermo Scientific SOLA CX SPE cartridges and an Accucore aQ core-shell column for simultaneous extraction and determination of HCTZ and losartan from human plasma within two minutes. The main objectives were to assess method precision, recovery, linearity, sensitivity, and carryover.

Methodology and Instrumentation

• Sample preparation: 100 µL plasma aliquot spiked with analytes and internal standard; SPE on 10 mg/1 mL SOLA CX cartridges conditioned with methanol and water; wash with water containing 0.1 % formic acid; elution with acetonitrile containing 3 % ammonia; dry and reconstitute in 100 µL 80:20 water/acetonitrile.
• Chromatography: Thermo Scientific Accela 600 UHPLC with Accucore aQ column (50 × 2.1 mm, 2.6 µm); mobile phases water and acetonitrile (0.1 % formic acid); gradient 20–70 % B in 2 min; flow rate 0.4 mL/min; column temperature 40 °C; injection volume 2.5 µL.
• Mass spectrometry: Thermo Scientific TSQ Vantage with HESI source; positive ion mode for losartan, negative for HCTZ; optimized transitions and parameters; cycle time 0.5 s.
• Data processing: Thermo Scientific LC Quan software.

Main Results and Discussion

• Linearity: Both analytes linear from 0.5 to 500 ng/mL (r² = 0.9974 for HCTZ, r² = 0.9956 for losartan).
• Precision: RSD below 6.1 % at low and high QC levels for both compounds.
• Recovery: Mean recoveries of 86.4 % for HCTZ and 65.8 % for losartan.
• Carryover: No detectable carryover for HCTZ; minimal carryover for losartan addressed by two blank injections.

Benefits and Practical Applications

• Significant reduction in solvent consumption and sample volume compared to conventional SPE.
• Fast turnaround with a 2-minute chromatographic runtime enhances throughput.
• High reproducibility and sensitivity enable reliable quantitation in clinical and bioanalytical settings.
• Method simplicity supports routine implementation in drug monitoring and pharmacokinetic studies.

Future Trends and Applications

• Development of next-generation SPE media with improved analyte specificity and reduced matrix effects.
• Integration with automated sample handling and microfluidic systems for ultra-high throughput.
• Expansion to multiplexed assays covering diverse drug classes in a single run.
• Coupling with high-resolution mass spectrometry and advanced data analytics, including machine learning.
• Adoption of greener solvents and sustainable extraction protocols.

Conclusion

The combination of SOLA CX SPE cartridges and an Accucore aQ core-shell column provides a robust, fast, and sensitive LC-MS/MS method for simultaneous quantification of HCTZ and losartan in human plasma. Excellent precision, recovery, and linearity, along with minimal carryover, demonstrate its suitability for high-throughput clinical bioanalysis.