Direct Injection of Blood Plasma for the Determination of Drugs using “Co-Sense for BA” (Part 5)

Significance of the Topic

Direct bioanalysis of drugs in blood plasma is essential for pharmacokinetic studies, therapeutic drug monitoring and toxicology. Automating pretreatment steps such as deproteinization reduces human error, shortens turnaround times and increases laboratory throughput. The Co-Sense for BA system enables direct injection of filtered plasma or serum, streamlining workflows in clinical and industrial laboratories.

Study Objectives and Overview

This application report demonstrates the determination of multiple drug classes in blood plasma using the Co-Sense for BA LCMS-2010A single-quadrupole system. The study covers basic drugs, nonsteroidal anti-inflammatories and vitamin K antagonists, focusing on sensitivity, reproducibility and matrix cleanup efficiency under various electrospray ionization modes.

Methodology and Instrumentation

The Co-Sense for BA platform automates sample deproteinization via an integrated pretreatment column and switching valves (Valve A, Valve B, Valve C) as shown in the flow diagram. A mixture of 0.1% formic acid in acetonitrile/water (1:4 v/v) flushes lines between injections to minimize carryover. Key components and conditions:

• Autosampler: SIL-HT
• Pretreatment column and analytical columns: Shim-pack MAYI-ODS (10 mm L.×4.6 mm I.D.), Chromolith SpeedRod (50 mm×4.6 mm I.D.), Shim-pack FC-ODS (75 mm×4.6 mm I.D.)
• Mobile phases: acidic (0.1% formic acid) or buffered (10 mM ammonium formate, pH 3.7) A/B gradients with acetonitrile
• Flow rates: 0.5–3.0 mL/min; column temperature: 40 °C
• ESI modes: positive (4.5 kV) for basic drugs, ketoprofen, warfarin; negative (–3.5 kV) for ibuprofen
• MS detection: selected ion monitoring (SIM) of [M+H]+ or deprotonated ions

Main Results and Discussion

Basic drugs (noscapine, propranolol, diphenhydramine, imipramine, verapamil) at 10 ng/mL spiked in plasma were resolved in a 2–5 minute gradient and detected with clear SIM peaks and minimal matrix interference. Ketoprofen and warfarin (100 ng/mL) showed distinct positive‐mode signals under a 2–5 minute gradient on FC-ODS with ammonium formate buffer. Ibuprofen (100 ng/mL) was effectively detected in negative mode on FC-ODS within a 2–4 minute run. Total cycle times including pretreatment, separation, column wash and equilibration averaged ten minutes, demonstrating high throughput. Carryover was negligible due to the washing protocol.

Practical Benefits and Applications

The automated direct-injection approach reduces manual sample handling, lowers solvent consumption and accelerates routine bioanalysis in clinical, pharmacology and QA/QC laboratories. The flexibility to switch ionization modes and mobile-phase chemistries allows multi-class drug panels to be analyzed in a single workflow.

Future Trends and Potential Applications

• Integration of tandem MS (MRM) or high-resolution mass spectrometry for increased specificity and multiplexing
• Microflow and sub-2 µm particles for higher sensitivity and lower solvent use
• Artificial intelligence–driven data processing for automated peak identification and quantification
• Expansion to endogenous biomarkers and metabolites for comprehensive clinical profiling
• Point-of-care and bedside applications using simplified, portable LC-MS platforms

Conclusion

The Co-Sense for BA LCMS-2010A system demonstrates robust, high-throughput direct analysis of diverse drug classes in blood plasma. Automated pretreatment and optimized chromatographic conditions deliver rapid, reproducible results with minimal carryover, making this approach highly attractive for modern bioanalytical laboratories.

Used Instrumentation

• Co-Sense for BA biosample analysis system
• Shimadzu LCMS-2010A single-quadrupole LC-MS
• Autosampler SIL-HT
• Shim-pack MAYI-ODS, Chromolith SpeedRod, Shim-pack FC-ODS columns

Reference

• Shimadzu Application News No. L285
• No. L286
• No. L293
• No. L305