Detection of typical GCMS Pesticides in Cannabis Matrix utilizing APCI-LCMS

Significance of the Topic

With the rapid expansion of both medicinal and recreational cannabis markets, stringent pesticide testing protocols are essential to protect consumer health and meet evolving regulatory standards. While gas chromatography–mass spectrometry (GC-MS) has been the workhorse for many residual pesticide analyses, some analytes exhibit poor electrospray ionization, limiting LC-MS applications. Atmospheric pressure chemical ionization (APCI) coupled with LC-MS/MS addresses this gap by improving ionization efficiency across diverse pesticide chemistries and enabling a streamlined, single-instrument workflow.

Objectives and Study Overview

The primary goal of this study was to develop and validate an APCI-LCMS/MS method capable of quantifying ten pesticides commonly regulated in California and Oregon cannabis programs. Key objectives included optimizing ionization conditions, establishing multiple reaction monitoring (MRM) transitions, constructing matrix-matched calibration curves, and determining limits of quantitation (LOQs) in a cannabis flower matrix.

Methodology and Instrumentation

Sample Preparation:

• Dried cannabis flower (1 g) was spiked with pesticide mix (2 µg/g), extracted with 10 mL acetonitrile, ground, centrifuged, and diluted in blank extract for calibration.

Chromatographic Conditions:

• UHPLC: Restek Raptor ARC-18 column (100 × 2.1 mm, 2.7 µm), mobile phases water (A) and methanol (B), flow rate 0.4 mL/min, gradient from 3 % to 100 % B over 12 min, 40 °C column temperature.

Mass Spectrometry:

• Shimadzu LCMS-8060 triple quadrupole with APCI source in positive/negative polarity switching.
• MRM transitions optimized for each pesticide; three transitions per compound where applicable.
• Calibration range: 0.0078–2 µg/g with 1/C weighting, matrix-matched standards.

Main Results and Discussion

All ten pesticides achieved LOQs well below California and Oregon action levels, with signal-to-noise ratios >10 and precision (%RSD) under 14 %. Calibration curves exhibited excellent linearity (R2 ≥ 0.996). Representative chromatograms and MS/MS spectra confirmed clean separation and reliable detection of analytes such as abamectin, methyl parathion, and pentachloronitrobenzene in complex cannabis matrices.

Benefits and Practical Applications

This APCI-LCMS/MS approach consolidates multiple pesticide tests into one robust assay, reducing instrument turnover and sample handling. Laboratories can achieve sensitive, high-throughput screening of diverse pesticide classes without reliance on separate GC-MS methods, improving workflow efficiency and data consistency.

Future Trends and Applications

Emerging directions include broadening the analyte panel to include novel pesticides and metabolites, integrating automated sample preparation for increased throughput, and applying high-resolution accurate-mass detection for confirmation. Portable or benchtop APCI-LCMS systems may further enable on-site testing in cultivation and processing facilities.

Conclusion

The developed APCI-LCMS/MS method on the Shimadzu LCMS-8060 provides sensitive, precise, and linear quantitation of ten regulated pesticides in cannabis flower. LOQs fall below regulatory thresholds, demonstrating that a single LC-MS platform can replace dual-technique workflows and support reliable compliance testing.

References

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