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. Hydrochlorothiazide (HCTZ) and losartan are widely prescribed to manage hypertension and associated conditions. Reliable quantification of these polar analytes at trace levels in complex biological matrices supports clinical decision-making and drug development. The use of solid phase extraction (SPE) combined with high performance liquid chromatography and tandem mass spectrometry (LC-MS/MS) enables sensitive, rapid analysis suitable for high throughput laboratories.

Objectives and Study Overview

This study demonstrates a streamlined workflow for simultaneous extraction and determination of HCTZ and losartan from human plasma using novel SOLA CX SPE cartridges and an Accucore aQ UHPLC column. Key goals include reducing solvent consumption, minimizing sample volume, achieving fast chromatographic separation, and maintaining high precision and recovery.

Methodology and Instrumentation

• Sample Pretreatment: Aliquot 121.4 µL of spiked plasma with appropriate internal standard, add methanol and mix.
• SPE Extraction: Condition SOLA CX 10 mg/1 mL cartridges with methanol and water; load 100 µL sample; wash with water plus 0.1 % formic acid; elute with acetonitrile containing 3 % ammonia; dry and reconstitute in 80:20 water/acetonitrile.
• Chromatography: Thermo Scientific Accela 600 UHPLC, Accucore aQ column (50×2.1 mm, 2.6 µm); gradient from 20 % to 70 % acetonitrile with 0.1 % formic acid in 2 minutes; flow rate 0.4 mL/min; column temperature 40 °C; injection volume 2.5 µL.
• Mass Spectrometry: Thermo Scientific TSQ Vantage with heated electrospray ionization; positive mode for losartan, negative for HCTZ; optimized transitions and collision energies; cycle time 0.5 s.

Main Results and Discussion

• Precision: Relative standard deviation below 6.1 % for both analytes at low (1.5 ng/mL) and high (400 ng/mL) QC levels.
• Recovery: Mean extraction recoveries of 86.4 % for HCTZ and 65.8 % for losartan.
• Linearity: Calibration linear across 0.5–500 ng/mL with correlation coefficients of r2 = 0.9974 for HCTZ and r2 = 0.9956 for losartan.
• Carryover: No detectable carryover for HCTZ; losartan required two blank injections post highest standard to ensure no residual signal.
• Sensitivity and Peak Shape: Good chromatographic peaks achieved within a two-minute run time, supporting high throughput analysis.

Benefits and Practical Applications

The proposed method significantly reduces solvent usage and sample preparation time compared to loose-packed SPE. Its rapid run time and robust performance make it well suited for clinical pharmacokinetic studies, therapeutic drug monitoring, and large-scale bioanalysis in pharmaceutical research.

Future Trends and Potential Applications

Advancements in polymer-based SPE media and core shell UHPLC technology will further enhance sensitivity and throughput. Integration with automated sample handling platforms could streamline workflows in regulated laboratories. Expanding this approach to additional polar drug compounds will support broader clinical and bioanalytical applications.

Conclusion

The combination of SOLA CX SPE cartridges and Accucore aQ chromatography delivers a fast, reproducible, and sensitive LC-MS/MS method for quantifying HCTZ and losartan in human plasma. This workflow meets the demands of high throughput laboratories while maintaining analytical quality and cost efficiency.

Reference

• Jones J and Phipps K, LC-MS/MS Method for the Determination of HCTZ and Losartan from Human Plasma Using SOLA CX, Thermo Fisher Scientific Application Note ANCCSSOLAHZ&LN.