Food Safety Applications NotebookEnvironmental Contaminants - Environmental Contaminants

Significance of the Topic

Biogenic amines such as histamine, tyramine, putrescine, spermidine, and spermine are important quality and safety markers in foods. They arise from amino acid decarboxylation by microorganisms during storage, processing, and fermentation. Consumption of elevated amine levels can lead to toxicological effects, including hypotension, migraines, and gastrointestinal distress. Reliable monitoring of these compounds in fresh produce and chocolate is essential for food quality control and consumer safety.

Objectives and Overview of the Update

This Application Update extends previously described IonPac CS18 methods to the determination of underivatized biogenic amines in kiwifruit, spinach, and chocolate. The goals are to demonstrate: 1) sample extraction protocols suitable for plant and confectionery matrices; 2) compatibility of electrolytically generated methanesulfonic acid (MSA) gradients with suppressed conductivity and integrated pulsed amperometric detection (IPAD); and 3) the use of UV absorbance to confirm aromatic amines in complex matrices.

Methodology and Sample Preparation

• Instrument Configuration
  • Dionex ICS-3000 system with EG Eluent Generator (EGC II MSA), DP-3000 pump, DC module (dual-temperature), and AD25 UV detector.
  • IonPac CS18 analytical column (2 × 250 mm) with CG18 guard (2 × 50 mm).
  • Postcolumn base addition: 100 mM NaOH at 0.24 mL/min for IPAD.
  • Detection: suppressed conductivity (CSRS ULTRA II, external water), IPAD (Au electrode), and UV at 276 nm for tyramine confirmation.
• Eluent Program
  • Online generation of 3–45 mM MSA gradient via EGC II MSA.
  • Flow rate 0.30 mL/min at 40 °C.
• Sample Extraction
  • Kiwifruit and spinach: homogenize 5 g of tissue with 10 mL of 5% trichloroacetic acid (TCA), centrifuge, and repeat. Dilute supernatant 1:1 with water.
  • Chocolate: defat 2 g sample with hexane, dry, then extract amines with 5% TCA in water, centrifuge, filter, and dilute 1:2.
  • Filtration through 0.2 μm syringe filters before analysis.

Main Results and Discussion

• Linearity and Detection Limits
  • Biogenic amines showed linear responses (r² > 0.997) over 0.1–10 mg/L ranges.
  • Suppressed conductivity LODs were 2–20 μg/L; IPAD LODs were 20–400 μg/L.
  • Post-suppression IPAD increased baseline noise and LODs to 100–1100 μg/L.
• Precision and Reproducibility
  • Intraday peak area RSDs: 0.8–2.9% (conductivity), 1.2–4.0% (IPAD).
  • Between-day RSDs over 10 days: <7% for most amines.
• Matrix Analyses
  • Kiwifruit: detected putrescine (4.8 mg/kg) and spermidine (2.9 mg/kg); histamine and tyramine were below LOD.
  • Spinach: higher putrescine (9.7 mg/kg) and spermine (1.5 mg/kg); low histamine (0.6 mg/kg).
  • Dark chocolate: elevated levels of tyramine (12.3 mg/kg) and histamine (3.8 mg/kg), confirmed by UV; plus putrescine (15.2 mg/kg), spermidine (18.5 mg/kg).

Benefits and Practical Applications

• The CS18 column with MSA gradient enables fast, robust separations of underivatized amines without organic modifiers.
  
• Suppressed conductivity provides low-noise detection for primary aliphatic amines; IPAD extends coverage to aromatic and heterocyclic amines.
  
• UV absorbance at 276 nm provides orthogonal confirmation of tyramine in complex matrices.
  
• Method workflows are streamlined through online eluent generation and automated sample injection, reducing manual preparation errors.

Future Trends and Potential Uses

• Extension to other fruit and vegetable varieties to build an amine profile database for freshness and authenticity assessment.
  
• Integration with high-resolution mass spectrometry for definitive identification of unknown amine-like peaks.
  
• Coupling with automated sample preparation (SPE or ASE) for high-throughput screening in QA/QC laboratories.
  
• Development of rapid on-line IC monitoring systems for process control in food manufacturing.

Conclusion

The IonPac CS18 column combined with suppressed conductivity and IPAD provides a powerful platform for the analysis of underivatized biogenic amines in diverse food matrices, including fruits, vegetables, and chocolate. The method delivers excellent sensitivity, precision, and selectivity without complex derivatization, streamlining food safety and quality assessments.

Reference

AN 183: Determination of Biogenic Amines in Fermented and Non-Fermented Foods Using Ion Chromatography with Suppressed Conductivity and Integrated Pulsed Amperometric Detections