Ultra-fast screening of pesticides in foods and agricultural products with desorption corona beam ionization (DCBI) tandem mass spectrometry

Significance of the topic

Rapid and reliable detection of pesticide residues in food and agricultural products is essential for ensuring consumer safety and meeting regulatory standards. Traditional chromatographic methods provide high sensitivity but involve lengthy sample preparation and analysis times, limiting overall throughput.

Objectives and study overview

This study aims to establish an ultra-fast screening workflow for pesticides using desorption corona beam ionization (DCBI) combined with tandem mass spectrometry and multiple reaction monitoring (MRM). The goal is to achieve high-throughput analysis with minimal sample preparation and rapid data acquisition.

Methodology

Samples are ionized directly under ambient conditions using a visible helium corona beam (DCBI) that strikes the sample surface, producing predominantly protonated molecules. Three ionization modes (DCBI, electrospray ionization, and atmospheric pressure chemical ionization) were compared for 37 pesticide standards to select the optimal ionization conditions. MRM transitions were automatically optimized in flow-injection mode using authentic standards and LabSolutions control software. A Shimadzu triple quadrupole mass spectrometer (LCMS-8040 or LCMS-8050) capable of acquiring over 555 MRM channels per second was employed, achieving complete data acquisition in approximately 30 seconds per sample.

Used instrumentation

• Shimadzu Desorption Corona Beam Ionization (DCBI) source
• Shimadzu LCMS-8040 and LCMS-8050 triple quadrupole mass spectrometers
• LabSolutions LC/MS control software for automated MRM optimization
• Glass capillaries and sample cups for direct sample introduction

Main results and discussion

• DCBI produced primarily simple protonated ions ((M+H)+) for 37 pesticides, with fewer adducts than ESI or APCI, facilitating straightforward MRM quantification.
• Optimized MRM parameters (2–4 transitions per compound, 5 ms dwell time, 1 ms pause, 0.65 s loop time) ensured sensitive and selective detection.
• Ultra-fast MRM acquisition enabled analysis of each sample in about 30 seconds, compared to traditional LC methods requiring 20–40 minutes.
• Spiked cucumber homogenates (10 ppb) yielded satisfactory recoveries, demonstrating applicability to real agricultural matrices, with opportunities for further optimization of sample treatment and ionization settings.

Benefits and practical applications of the method

• Significantly increased sample throughput supports large-scale screening in food safety laboratories.
• Minimal sample preparation reduces labor, solvent use, and turnaround time.
• Applicability to QA/QC environments, environmental monitoring, and rapid field-based screening.

Future trends and potential applications

Advances may include integration with fully automated sampling systems, expansion of the pesticide library, enhanced sensitivity and selectivity through refined DCBI parameters, and on-site deployment for border control or remote testing.

Conclusion

The DCBI-MRM workflow on ultra-fast triple quadrupole instruments offers a robust, high-throughput approach for pesticide screening in food samples. By combining direct ambient ionization with rapid MRM acquisition, this method substantially reduces analysis time while maintaining reliable detection, paving the way for broader implementation in food safety and environmental applications.

References

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• Huang Y., et al. J. Chromatogr. A 1218:7371–7376 (2011).
• Cheng S., et al. ASMS Proc. (2012).
• Zhao Y., et al. Chinese Journal of Food Hygiene 24(4):312–317 (2012).
• Du W., et al. Talanta 131:499–504 (2015).