Aflatoxin Immunoaffinity Chromatography with Automated Vacuum Manifold

Significance of the topic

Aflatoxins are heat-stable fungal metabolites that concentrate in food commodities such as corn and peanuts and present serious health risks including carcinogenicity. Regulatory testing therefore requires selective, sensitive, and high-throughput analytical workflows that deliver trace-level quantification with robust sample cleanup. Immunoaffinity column (IAC) cleanup remains a gold-standard approach for selective extraction of aflatoxins, but traditional manual implementations are labor intensive and susceptible to operator variability. Automating the IAC workflow addresses throughput, reproducibility, and data integrity needs in routine testing laboratories.

Objectives and study overview

This study evaluated an automated immunoaffinity cleanup workflow for aflatoxins based on AOAC Official Method 991.31, using the Extraction+ connected-device vacuum manifold controlled by OneLab software and assisted pipetting by Pipette+ where applicable. Key aims were to: (1) implement programmable vacuum pressure gradients to control flow through AflaTest IAC cartridges and mitigate clogging, (2) demonstrate equivalent or improved analytical performance (linearity, recovery, precision) across a broad concentration range in corn, and (3) show integration with laboratory informatics (LIMS) and Empower chromatography software to enable traceable, end-to-end sample handling and data transfer.

Methodology

The sample preparation followed AOAC 991.31 with modifications for automation. Ground corn (25 g) was extracted with 70% methanol/NaCl, filtered, diluted, filtered again, and loaded onto AflaTest IAC cartridges. The automated Extraction+ vacuum manifold processed up to 24 samples concurrently using controlled vacuum gradients to regulate flow during load, wash, and elution steps. Elution used 1.0 mL methanol, diluted 1:1 with water, and analysis was performed by UPLC with fluorescence detection. Calibration and spike-recovery studies covered 0.1–100 ng/g for aflatoxins B1, B2, G1, and G2.

Instrumentation used

The main instruments and consumables reported were:

• Extraction+ connected-device vacuum manifold (for automated IAC cleanup)
• Pipette+ connected device (assisted/automated pipetting where applicable)
• AflaTest immunoaffinity cartridges (Waters VICAM AflaTest)
• ACQUITY UPLC H-Class PLUS System with FTN autosampler
• ACQUITY UPLC FLR Detector (Excitation 360 nm / Emission 440 nm; data rate 10 pts/s)
• ACQUITY UPLC HSS T3 column, 1.8 µm, 2.1 x 100 mm
• Filters and consumables: fluted filter paper and microfiber filters from VICAM
• Software: OneLab for device control and workflows, Empower (v3.6.1) for chromatography data handling, and integration with laboratory LIMS

UPLC conditions were isocratic 45% methanol at 0.350 mL/min, 5 µL injection, 6-minute run time, room temperature column.

Main results and discussion

The automated Extraction+ workflow achieved analytical performance comparable to AOAC 991.31 while improving throughput and reproducibility. Key performance outcomes included:

• Linearity: calibration R² ≥ 0.995 across 0.1–100 ng/g for all four aflatoxins.
• Recoveries: mean recoveries ranged ~95–110% for B1, B2, G1, and G2 in spiked corn.
• Precision: within-run reproducibility was <10% RSD.
• Throughput: system can process up to 24 samples in parallel in a compact footprint, reducing hands-on time by approximately 50% versus manual preparation.
• Robustness: programmable vacuum pressure gradients maintained controlled flow, minimized cartridge clogging with particulate-rich or viscous extracts, and provided consistent loading and elution.

The results indicate that the controlled vacuum approach is an effective alternative to positive-pressure manifolds or fully manual processing, providing consistent cartridge performance while using modest vacuum capacity. Integration with OneLab enabled standardized, reproducible sequences for loading, washing, and elution and supported assisted or manual pipetting protocols as needed.

Benefits and practical applications of the method

The automated IAC workflow offers several practical advantages for routine aflatoxin testing laboratories:

• Higher throughput and lower labor costs due to parallel processing and reduced hands-on time.
• Improved reproducibility and reduced operator-to-operator variability through programmable pressure profiles.
• Maintained AOAC-level selectivity and quantitative performance for regulatory compliance.
• Enhanced robustness for challenging matrices by preventing flow interruptions and cartridge blockage.
• Digital traceability and reduced transcription errors by integrating OneLab with LIMS and Empower for automated sample lists, chain-of-custody, and chromatographic data transfer.

Future trends and potential applications

Automation of immunoaffinity-based cleanup is aligned with broader laboratory trends toward higher throughput, digitalization, and tighter data governance. Anticipated developments and opportunities include:

• Expansion of automated, cartridge-based cleanup for other mycotoxins and contaminant classes using tailored pressure profiles.
• Greater integration with laboratory information systems and enterprise data platforms for centralized sample management and audit-ready traceability.
• Adoption of modular automation (connected pipetting and vacuum manifolds) to retrofit existing workflows with minimal capital outlay.
• Implementation of predictive maintenance and process analytics to further reduce downtime and optimize vacuum gradients for diverse matrices.

Conclusions

Implementation of the Extraction+ connected-device vacuum manifold driven by OneLab software successfully automated AOAC 991.31 AflaTest immunoaffinity cleanup for corn. The system delivered AOAC-comparable analytical performance (excellent linearity, 95–110% recoveries, <10% RSD) over 0.1–100 ng/g while halving hands-on time and enabling 24-sample parallel processing. Programmable vacuum gradients improved robustness against clogging and ensured reproducible cartridge performance. Integration with LIMS and Empower supports full digital traceability and streamlined data transfer, making this automated approach attractive for high-throughput routine testing laboratories.

References

1. AOAC INTERNATIONAL. Aflatoxins in Corn, Raw Peanuts, and Peanut Butter, Immunoaffinity Column (AflaTest) Method 991.31 (2005).
2. Sun T., Dreolin N., Hird S., Collette N. Analysis of Aflatoxins in Corn and Peanuts Using Immunoaffinity Chromatography and the Arc HPLC System. Waters Application Note (2023).
3. Benvenuti M.E., Di Gioia A.J. Rapid Analysis of Aflatoxins without Derivatization Using Ultra Performance Liquid Chromatography and Fluorescence Detection. Waters Application Note (2019).