Extraction of Patulin From Clear Apple Juice Using ISOLUTE® Myco prior to LC-MS/MS Analysis

Significance of the Topic

Patulin is a mycotoxin produced by Aspergillus and Penicillium species on decaying apples. Although its acute toxicity is moderate, patulin exhibits genotoxic and potentially carcinogenic properties. Regulatory bodies worldwide limit patulin in apple products to protect public health, with a maximum of 10 µg/kg in apple juice. Developing reliable extraction and quantitation methods for patulin is essential for routine quality control and regulatory compliance in the food industry.

Study Objectives and Overview

This application note presents a solid phase extraction (SPE) protocol using ISOLUTE® Myco columns to isolate patulin from clear apple juice, followed by quantitative analysis via LC–MS/MS. The aim is to achieve high recovery rates, low relative standard deviations (RSDs), and a limit of quantitation (LOQ) aligned with regulatory thresholds.

Methodology

Sample Preparation Procedure:

• Dilute clear apple juice 1:1 with 10 mM ammonium acetate buffer (pH 5) and adjust pH to 5 using concentrated ammonium hydroxide.
• Condition ISOLUTE Myco 60 mg/3 mL columns with acetonitrile (2 × 1 mL), then equilibrate with ammonium acetate buffer (1 mL).
• Load 1 mL of pretreated sample onto the column.
• Wash sequentially with ammonium acetate buffer (3 × 1 mL), dry under pneumatic pressure (2 bar/29 psi), wash with toluene (1 mL), and dry again.
• Elute patulin with acetonitrile (1 mL). Evaporate eluate under air or nitrogen, and reconstitute in 500 µL water prior to analysis.

Used Instrumentation

• Solid Phase Extraction: ISOLUTE Myco 60 mg/3 mL columns (Biotage). Manifold: Biotage PRESSURE+ 48 or VacMaster vacuum manifold.
• Liquid Chromatography: Waters Alliance 2795 with Kinetex phenyl-hexyl column (50 × 2.1 mm, 2.6 µm).
• Mobile Phases: Water (A) and acetonitrile (B) with gradient elution at 0.3 mL/min over 4.5 min.
• Mass Spectrometry: Waters Ultima Platinum QQQ in negative electrospray ionization and multiple reaction monitoring (MRM).

Main Results and Discussion

The SPE–LC–MS/MS workflow delivered an average patulin recovery of 101% (n = 7) with RSDs below 10%. Hydroxymethylfurfural (HMF), a common matrix interferent, was baseline‐resolved from patulin. The LOQ was established at 10 µg/kg (signal-to-noise ratio ≥16:1), satisfying regulatory requirements. Calibration over 2–200 ng/mL exhibited excellent linearity (r² > 0.99).

Benefits and Practical Applications

• High-throughput, reproducible extraction of patulin from clear apple juice.
• Robust removal of interfering compounds like HMF.
• Meets international regulatory limits for patulin quantitation.
• Adaptable to routine quality assurance in juice production and regulatory laboratories.

Future Trends and Applications

Extension of the ISOLUTE Myco SPE approach to cloudy juices and solid apple products, incorporating enzymatic digestion (e.g., pectinase) for improved matrix breakdown. Integration with automated SPE platforms and miniaturized LC–MS/MS systems may further increase throughput. Expansion to multiplexed mycotoxin screening could streamline comprehensive food safety testing.

Conclusion

The described SPE protocol using ISOLUTE Myco columns, combined with LC–MS/MS detection, provides a sensitive, precise, and regulatory-compliant method for quantifying patulin in clear apple juice. High recoveries, low RSDs, and effective interference removal make this approach suitable for routine monitoring and ensuring consumer safety.

References

No external literature references were cited in the source document.