High-Speed Simultaneous Analysis of Amino Acids by Pre-column Derivatization Using Automatic Pretreatment Function

Significance of the Topic

Amino acid profiling is critical in food, pharmaceutical, and biochemical research to ensure product quality, nutritional assessment, and regulatory compliance. Traditional post-column derivatization methods, while sensitive, limit throughput and involve more manual steps. Automated pre-column derivatization streamlines sample preparation, minimises reagent consumption, and enables high-speed analysis of multiple amino acids simultaneously.

Objectives and Study Overview

This work demonstrates a rapid, automated pre-column derivatization approach for quantifying 20 proteinogenic amino acids using the Shimadzu Nexera™ XR system. The aim was to complete derivatization, separation, and detection in a single 24-minute cycle with excellent precision and linearity.

Methodology and Derivatization Workflow

• Automatic pretreatment mixes sample with O-phthalaldehyde/mercaptopropionic acid (OPA/MPA) and 9-fluorenylmethyl chloroformate (FMOC) directly in the autosampler needle.
• Derivatization reactions occur at ambient temperature: a 2-minute wait for OPA/MPA and iterative mixing for FMOC to label proline.
• Injection of 1 µL into a Shim-pack™ XR-ODSII column (100×3.0 mm, 2.2 µm) under a low-pressure gradient using acetate buffers, water/acetonitrile, and EDTA-containing mobile phase.
• Fluorescence detection at Ex. 350 nm/Em. 450 nm for OPA derivatives and Ex. 266 nm/Em. 305 nm for FMOC derivatives.

Instrumentation Used

• High-Performance Liquid Chromatograph: Shimadzu Nexera™ XR
• Fluorescence Detector: RF-20AXS
• Autosampler with automatic pretreatment function
• Analytical Column: Shim-pack™ XR-ODSII (100 mm × 3.0 mm, 2.2 µm)

Main Results and Discussion

• Complete resolution and quantification of 20 amino acids in 24-minute runs.
• Calibration curves exhibited excellent linearity (r² ≥ 0.999) across 1–100 µmol/L.
• Repeatability of peak areas showed low variability (RSD < 2% for most analytes; proline ≈ 5%).
• Application to beer samples (10× and 100× dilution) produced clear chromatograms and reliable quantification.

Benefits and Practical Applications

• High throughput suited for routine quality control in food, beverage, and pharmaceutical laboratories.
• Significant reduction in manual handling and reagent usage via automated derivatization.
• Versatility of the Nexera XR platform allows adaptation to other compound classes.

Future Trends and Possibilities

Advancements may include microflow or nano-HPLC formats, integration with mass spectrometry for enhanced sensitivity and specificity, and AI-driven method optimization for gradient and derivatization protocols.

Conclusion

The automated pre-column derivatization method on Nexera XR delivers rapid, reproducible analysis of proteinogenic amino acids with high precision and throughput. Its streamlined workflow and versatility make it a valuable asset for diverse analytical laboratories.