Analysis of Fungicide on the Peel Surface of Imported Oranges (2) — Identifying Substances by MS/MS Analys

Importance of the Topic

In global produce trade, swift and reliable detection of post-harvest pesticide residues is crucial to protect consumer health and comply with import regulations. Traditional chromatographic methods often demand extensive sample preparation and lengthy run times. A streamlined approach that combines direct probe ionization with high-resolution mass spectrometry can significantly reduce inspection time and improve throughput for routine quality control.

Objectives and Study Overview

This study evaluates the performance of a Shimadzu LCMS-9050 Q-TOF mass spectrometer coupled with a DPiMS™ QT direct probe ionization kit for detecting the fungicide enilconazole on orange peel surfaces. Building on prior pretreatment methods, the work aims to demonstrate rapid presence/absence screening and confirmatory MS/MS identification using minimal sample handling.

Methodology

The peel surface of imported oranges was pretreated following a simple extraction protocol. Direct probe ionization introduced the sample into the MS system operating in positive-ion mode. Full-scan MS data were acquired over m/z 50–1000, targeting the protonated enilconazole at m/z 297.0555 with mass accuracy better than ±1 ppm. Subsequent MS/MS experiments were conducted over m/z 50–350 with a collision energy of 25 eV. Each analysis was completed in approximately 0.5 minutes, enabling rapid sample turnaround.

Used Instrumentation

• Shimadzu LCMS-9050 high-resolution Q-TOF mass spectrometer
• Shimadzu DPiMS™ QT direct probe ionization system

Main Results and Discussion

Full-scan MS of both the enilconazole standard and orange peel extract produced a distinct signal at m/z 297.0555 with characteristic isotopic distribution, confirming accurate mass detection. MS/MS spectra from the peel extract matched the standard’s fragment ion profile, demonstrating unambiguous structural confirmation of the fungicide on the fruit surface. The agreement between standard and sample spectra validates the method’s specificity, even in a complex matrix.

Benefits and Practical Applications

This analytical workflow provides:

• Minimal sample preparation, reducing hands-on time
• Sub-minute analysis per sample for high throughput
• Accurate mass measurement combined with MS/MS structural confirmation
• Flexibility to detect various surface-borne contaminants

Future Trends and Possibilities

Future enhancements may include automated probe sample handling to further increase throughput, rapid switching between positive and negative ion modes to broaden analyte coverage, and integration with advanced data-processing software or AI-driven spectral libraries for streamlined on-site quality assurance. Adaptation of the method to other agricultural products and environmental samples could extend its application scope.

Conclusion

The combination of Shimadzu’s LCMS-9050 and DPiMS™ QT enables fast, accurate, and straightforward detection of post-harvest fungicides on food surfaces. Its rapid screening capability and confirmatory MS/MS analysis make it an effective tool for regulatory compliance and food safety monitoring.