Automated in-needle OPA/FMOC derivatization of amino acids analysis with the Thermo Scientific Vanquish Core HPLC system operated under Empower 3.8.0 CDS

Automated in-needle OPA/FMOC derivatization of amino acids using Vanquish Core HPLC controlled by Empower 3.8.0 — Summary

Significance of the topic

Amino acids are central analytes across research, food, beverage, clinical and industrial laboratories. Most proteinogenic amino acids lack strong native UV/visible chromophores, so pre-column derivatization with fluorogenic reagents (orthophthaldialdehyde, OPA, for primary amines; 9‑fluorenylmethyloxycarbonyl chloride, FMOC‑Cl, for secondary amines) is widely used to enable highly sensitive fluorescence detection. Manual derivatization is labor intensive and introduces variability. Automating in-needle derivatization within the autosampler reduces hands‑on time, improves reproducibility, and enhances laboratory throughput and safety, making it attractive for routine QC/QA and high‑throughput analyses.

Goals and overview of the application brief

The brief demonstrates implementation of a fully automated in‑needle OPA/FMOC derivatization workflow on a Thermo Scientific Vanquish Core HPLC system, operated under Waters Empower 3.8.0 chromatography data system using the Thermo Scientific SII for Empower plugin. The objectives were to show ease of setup, robustness of the automated derivatization, compatibility across vendor software, and routine data processing (calibration and sample quantitation) for amino acid analysis on an Accucore C18 column with fluorescence detection.

Methodology

Key methodological elements and workflow:

• Derivatization chemistry: OPA (with a thiol such as MPA) targets primary amino acids to form highly fluorescent isoindole derivatives (typical fluorescence excitation/emission approximately 337/442 nm). FMOC‑Cl derivatizes secondary amino acids producing derivatives with excitation/emission near 260/325 nm. A borate buffer (pH ~10) is used for FMOC reaction and acetic acid is used to quench OPA reaction.
• In‑needle automation: The autosampler executes a Custom Injection Program (CIP) in Replace normal injection mode. Sequential aspirate/dispense steps introduce reagent(s), buffer, and sample directly into the needle, allow derivatization to proceed in‑needle, then draw formed derivative into the sample loop for LC injection—removing the need for offline vial reactions.
• Chromatography and detection: Reversed‑phase separation on a Thermo Scientific Accucore C18 column (3 × 150 mm, 2.6 µm) with a compatible guard cartridge was used. Detection employed a Vanquish Fluorescence Detector with D‑PMT and a biocompatible flow cell (8 µL). Typical wavelengths for the two derivative types were used as above.
• Calibration and quantitation: Calibration standards (example concentration 75 µM for the standard shown) and quadratic fit were used for concentration estimation. Example real‑world sample: soy sauce diluted 1:1000 and processed through the automated workflow.

Instrumentation used

The setup reported in the brief comprised the following Thermo Scientific Vanquish Core modules and consumables:

• Vanquish Core System Base (VC‑S01‑A‑02)
• Vanquish Quaternary Pump C (VC‑P20‑A‑01)
• Vanquish Split Sampler CT with 100 µL stainless steel sample loop (VC‑A12‑A‑02; loop Cat. No. 6851.1950)
• Vanquish Column Compartment C with passive pre‑heater and stainless steel µ‑connect tubing
• Vanquish Fluorescence Detector F, D‑PMT (VF‑D51‑A) with 8 µL biocompatible flow cell (6079.4230)
• Accucore C18 analytical column, 3 × 150 mm, 2.6 µm (17126‑153030) with Accucore C18 guard cartridge (3 × 10 mm, 2.6 µm, 17126‑013005) and Unigard holder
• SureSTART 2 mL amber glass vials for standards and samples
• Thermo Scientific SII for Empower 1.3 plugin integrated into Waters Empower CDS (version 3.8.0) for instrument control, CIP setup and data processing.

Main results and discussion

Implementation highlights and analytical performance observations:

• Workflow integration: The Vanquish Core system was successfully operated from Empower 3.8.0 using the SII plugin. The plugin exposes instrument parameters and a wizard for method setup; the CIP table allowed definition of the in‑needle derivatization sequence.
• Separation and detection: Baseline separations of the tested amino acids were obtained on the Accucore C18 column with fluorescence detection. Representative chromatograms shown included a 75 µM equal‑concentration calibration standard and a processed soy sauce sample (diluted 1:1000).
• Quantitation: Empower data processing supports standard workflows (component lists, calibration curve fitting, integration settings). A quadratic calibration model was used for at least some analytes (tyrosine shown as example). The system enabled routine quantitation of amino acids in a complex food matrix.
• Robustness and reproducibility: Automating derivatization in the needle reduced manual handling variability and simplified sample workflows. The brief emphasizes cross‑platform reproducibility when porting the same in‑needle protocol between CDS environments.

Benefits and practical applications

Practical advantages demonstrated by this implementation:

• Full automation of the derivatization step reduces operator time and exposure to reagents, improving lab safety and throughput.
• In‑needle approach minimizes reagent volumes and waste and reduces variability related to timing and mixing compared with manual vial derivatization.
• Compatibility with Waters Empower via SII enables labs with mixed vendor environments to adopt Vanquish hardware without sacrificing CDS functionality such as CIPs and integrated data processing.
• Suitable for routine amino acid profiling in food, beverage, and other matrices where fluorescence‑sensitive detection and robust quantitation are required.

Future trends and opportunities

Potential developments and broader uses stemming from this workflow:

• Broader automation: Extending in‑needle chemistry to other derivatization schemes, on‑board sample cleanup, and high‑throughput batch processing.
• Detection alternatives: Coupling the automated derivatization with mass spectrometric detection (after adapting mobile phase and cleanup) to broaden specificity and analyte coverage, or using multiplexed fluorescence detection for increased dynamic range.
• Method standardization and accreditation: Automated, software‑driven workflows support standardized protocols required for regulated environments and inter‑laboratory reproducibility studies.
• Software integration: Further enhancements to CDS plugins and method wizards could enable easier sharing of instrument methods, CIP templates, and processing methods across labs.

Conclusion

The application brief demonstrates that fully automated in‑needle OPA/FMOC derivatization for amino acid analysis can be implemented reliably on Thermo Scientific Vanquish Core HPLC hardware controlled through Waters Empower 3.8.0 using the SII for Empower plugin. The approach delivers robust chromatographic separations, reliable quantitation, and practical benefits for routine laboratories, while supporting cross‑platform instrument control and standardized data processing workflows.

References

1. Huyn Park S., et al., Thermo Scientific Application Note 73151: Underivatized amino acid analysis in wine by HILIC separation and mass detection, 2019.
2. Bernal Soro A., et al., Thermo Scientific Customer Application Note 003698: Amino acid analysis in food, beverages, and fertilizers by automated in‑needle OPA/FMOC derivatization, 2025.
3. Grosse S., Thermo Scientific White Paper 72749: Using Thermo Scientific Vanquish HPLC and UHPLC systems with Waters Empower 3 chromatography data system (CDS), 2022.