Efficient Extraction of Quetiapine in Plasma Using Oasis PRiME MCX

Significance of the Topic

In bioanalytical workflows, reliable quantification of drug compounds in plasma hinges on effective removal of interfering matrix components such as phospholipids. Phospholipid-induced ion suppression can compromise method sensitivity and robustness, particularly in high-throughput environments. Advances in solid-phase extraction (SPE) materials that simplify sample preparation and enhance cleanliness are therefore crucial for accurate therapeutic drug monitoring and pharmacokinetic studies.

Objectives and Study Overview

This work compares three plasma sample preparation approaches for quetiapine analysis: protein precipitation (PPT), conventional Oasis MCX mixed-mode SPE, and the novel Oasis PRiME MCX µElution SPE. The goals were to evaluate extraction recovery, matrix effects, and phospholipid removal efficiency for each protocol, using a 96-well plate format to support high throughput.

Methodology and Used Instrumentation

Sample Preparation and Extraction Protocols:

• Calibrators (2.5–100 ng/mL) and QCs (7.5, 30, 75 ng/mL) prepared by spiking quetiapine into pooled human plasma.
• Three extraction workflows:
  • PPT: 1:3 methanol precipitation, centrifugation, direct supernatant analysis.
  • Oasis MCX: Acidified plasma (4 % phosphoric acid), SPE conditioning, washes (2 % formic acid, methanol), elution with 5 % NH₄OH in methanol plus water.
  • Oasis PRiME MCX: Acidified/diluted plasma (4 % phosphoric acid in 200 mM ammonium formate), no conditioning/equilibration, single methanol wash, elution identical to MCX.

Instrumentation:

• UPLC: ACQUITY UPLC I-Class with CSH C18 column (1.7 µm, 2.1×100 mm), 0.4 mL/min gradient elution over 4.3 min.
• Mass Spectrometry: Xevo TQD triple quadrupole, positive ESI, MRM transitions for quetiapine (384.1→253.05 and 384.1→221.1), source at 150 °C, desolvation at 600 °C.
• Data Processing: MassLynx v4.1 with TargetLynx.

Main Results and Discussion

Extraction Recovery:

• PPT yielded poor recovery (mean 27.7 %), with RSD≤2.0 %.
• Oasis MCX achieved 94.5 % recovery (RSD≤5.3 %).
• Oasis PRiME MCX delivered 94.0 % recovery (RSD≤8.5 %).

Matrix Effects and Ion Suppression:

• PPT showed severe ion suppression (mean –58.4 %).
• Oasis MCX limited suppression to –2.7 %.
• Oasis PRiME MCX further reduced effects (mean –0.1 %), indicating negligible interference.

Phospholipid Removal:

• Parent ion scan at m/z 184 demonstrated that Oasis PRiME MCX eliminated up to 98 % of phospholipids versus PPT, outperforming conventional MCX.

Benefits and Practical Applications of the Method

• Streamlined 3-step protocol (no conditioning/equilibration) shortens preparation time and reduces solvent use.
• µElution plate format allows direct injection, eliminating evaporation and reconstitution steps.
• High recovery and minimal matrix effects improve assay robustness and reproducibility.
• Suitable for automation on liquid handling platforms to enhance throughput and traceability.

Future Trends and Potential Applications

• Extension of Oasis PRiME MCX protocols to other basic drug compounds and metabolites in biological fluids.
• Integration with high-throughput screening and laboratory information management systems for streamlined bioanalysis.
• Development of next-generation sorbents targeting broader classes of endogenous interferences.
• Advances in microelution formats and sustainable solvent reduction techniques for greener workflows.

Conclusion

The Oasis PRiME MCX µElution SPE method for quetiapine in plasma provides comparable recovery to conventional MCX while dramatically reducing phospholipid content and matrix effects. The simplified three-step workflow enhances throughput and robustness without additional sample concentration steps, making it well suited for routine high-throughput bioanalytical applications.

Reference

1. Mohammad Mahdi Moeini, Aziza El Beqqali, Mohamed Abdel-Rehim. Bioanalytical method development and validation: Critical concepts and strategies. Journal of Chromatography B. 2017;1043:3–11.