Analysis of Captan, Folpet, and their Derivatives in Food with APCI-LCMS™-8060

Significance of the Topic

Captan and Folpet are phthalimide-based fungicides widely applied in agricultural production. Due to their toxicity and potential to degrade into hazardous byproducts, monitoring their levels in food is crucial to ensure compliance with regulatory limits and protect consumer health.

Objectives and Study Overview

This study aimed to establish a rapid, sensitive, and robust analytical protocol for quantifying Captan, Folpet, and their primary degradation products (Phthalimide and Tetrahydrophthalimide) in various food matrices. The method was designed to overcome thermal decomposition issues encountered in traditional GC/MS analyses.

Used Instrumentation

• Shimadzu Nexera X2 UHPLC system
• Shim-pack Scepter C18 column, 1.9 µm, 30 × 2.0 mm
• Shimadzu LCMS-8060 triple quadrupole mass spectrometer with APCI source

Methodology

Samples of rice, apple, orange, and matcha tea were prepared following the EN 15662:2018 QuEChERS protocol with dispersive SPE cleanup. Calibration standards were prepared in acetonitrile with 0.1 % acetic acid across 0.5 to 1000 ng/mL, diluted fivefold in aqueous 0.1 % acetic acid. Chromatographic separation was achieved in 10 minutes using a mobile phase of water with 10 mM ammonium acetate and methanol, at 200 µL/min and 40 °C. MRM transitions were optimized via flow injection analysis to enhance sensitivity under APCI conditions.

Main Results and Discussion

The method delivered linear calibration (r² > 0.99) with accuracies of 90–110 %. Limits of quantification in solvent reached 0.1 ng/mL, and in matrix ranged from 1 to 30 ppb, depending on the compound and food type. No carry-over was detected, and matrix extracts showed no interfering peaks at target retention times. Repeatability at LOQ levels yielded RSDs below 11 % across all matrices.

Benefits and Practical Applications

• Rapid 10-minute runtime suitable for high-throughput screening
• Sensitive detection below maximum residue limits defined in Regulation (EC) No 396/2005 and related directives
• Robust performance in complex matrices such as matcha tea
• Reduced risk of thermal degradation artifacts compared to GC/MS approaches

Future Trends and Opportunities

Expanding this workflow to multi-residue panels, integrating automated sample preparation, and coupling with high-resolution mass spectrometry could further enhance throughput and compound coverage. Advances in ionization sources and data processing algorithms are expected to boost sensitivity and selectivity for trace-level contaminant analysis.

Conclusion

The presented LC–APCI–MS/MS method on a Shimadzu LCMS-8060 platform offers a robust and sensitive alternative to GC/MS for monitoring Captan, Folpet, and related impurities in food. It meets regulatory requirements, demonstrates excellent reproducibility, and adapts well to diverse sample types.

Reference

• Regulation (EC) No 396/2005 on maximum residue levels of pesticides in food
• Directive 2007/5/EC amending Directive 91/414/EEC on active substances
• EN 15662:2018 method for pesticide residue analysis using QuEChERS