A four-column parallel chromatography system for isocratic or gradient LC/MS analyses

Area of Science:

• Analytical Chemistry
• Biochemistry
• Pharmacology

Background:

• Quantitative bioanalysis, particularly pharmacokinetic assays, demands high sample throughput.
• Conventional liquid chromatography/tandem mass spectrometry (LC/MS/MS) systems can be a bottleneck in high-throughput laboratories.
• Existing methods often require significant system modifications or specialized equipment.

Purpose of the Study:

• To present a novel, cost-effective parallel chromatography approach for LC/MS/MS analyses.
• To demonstrate the system's capability for enhancing sample throughput in quantitative applications.
• To validate the method's accuracy and precision using a real-world pharmacokinetic assay.

Main Methods:

• Modification of a conventional LC/MS system with three valves and four LC columns.
• Staggered injection of samples onto the four columns to enable continuous mass spectrometer analysis.
• Optimization of run time to slightly exceed the sum of desired peak widths.
• Application of both gradient and isocratic LC conditions.
• Analysis of atorvastatin, its metabolites, and deuterated internal standards in spiked human plasma.

Main Results:

• The parallel chromatography system achieved a throughput increase by a factor of 2.7 compared to conventional methods.
• Overall run time was reduced from 4.5 to 1.65 minutes for the specific analysis.
• Quality control samples exhibited relative standard deviation and accuracy within 8.1% and 9.6%, respectively.
• The system demonstrated robust performance under gradient elution conditions.

Conclusions:

• The developed parallel LC/MS/MS system offers a significant improvement in sample throughput for pharmacokinetic and quantitative assays.
• Modest system modifications allow for parallel analysis without compromising accuracy or precision.
• This approach provides a practical and efficient solution for high-throughput bioanalytical laboratories.