Multi pesticide residue analysis in tobacco by GCMS/MS using QuEChERS as an extraction method

Importance of Multi-Pesticide Residue Analysis in Tobacco

Tobacco is a high-value crop with significant global production and consumption. In tropical climates, pests and diseases are managed through extensive pesticide use, leading to potential residues in finished products. Monitoring these residues ensures consumer safety, supports regulatory compliance, and protects public health.

Study Objectives and Overview

This study aimed to develop a robust, sensitive, and cost-effective method for simultaneous detection and quantification of 203 pesticides in tobacco. The method adapts the QuEChERS extraction protocol paired with gas chromatography-tandem mass spectrometry (GC-MS/MS) for high throughput and reliable analysis within a single run.

Methodology and Instrumentation

• Sample Preparation: 2 g of dried tobacco leaf powder hydrated with 18 mL aqueous acetic acid, homogenized, and held for 30 minutes.
• Extraction: Addition of 10 mL ethyl acetate and 10 g sodium sulfate, homogenization at 15 000 rpm, centrifugation, and collection of the supernatant.
• Cleanup: Supernatant treated with 1 mL toluene and a sorbent mix (PSA, C18, GCB, MgSO₄), followed by vortexing, centrifugation, and PTFE filtration.
• Analysis: Injection of 2 µL cleaned extract into the Shimadzu GCMS-TQ8030 under splitless mode with a Rxi-5Sil MS column and optimized temperature program.
• MRM Optimization: Selection of precursor and product ions using argon collision energies to define MRM transitions for each pesticide.

Main Results and Discussion

The method achieved linearity for most compounds (R² > 0.995) across 0.5–25 ppb. Limits of quantification (LOQs) were 10 ppb or below for 90% of pesticides. Validation for Mevinphos (LOQ 1 ppb, R² = 0.9999, recovery 89%) and Parathion-ethyl (LOQ 5 ppb, R² = 0.9993, recovery 109%) demonstrated excellent precision and accuracy. The full MRM chromatogram confirmed clear separation of all analytes within a 41.87 min runtime.

Benefits and Practical Applications

• Comprehensive screening of 203 pesticides in a single run improves laboratory throughput and reduces analysis costs.
• High sensitivity and selectivity ensure reliable detection at trace levels, supporting regulatory compliance with CORESTA guidance levels.
• Applicability extends to other food and agricultural commodities requiring multi-residue monitoring.

Future Trends and Potential Uses

Ongoing advances in GC-MS/MS technology, such as faster scanning and improved ion transport, will further enhance throughput and sensitivity. Adapting the methodology to emerging contaminants, expanding spectral libraries, and integrating automated sample preparation are key trends. The approach can be extended to other complex matrices and integrated into regulatory monitoring frameworks worldwide.

Conclusion

A validated QuEChERS-GC-MS/MS method on the Shimadzu GCMS-TQ8030 delivers a rapid, sensitive, and reproducible solution for quantifying 203 pesticide residues in tobacco. The protocol meets stringent regulatory requirements and offers broad applicability for multi-residue analysis in diverse sample matrices.

Used Instrumentation

• Shimadzu GCMS-TQ8030 triple quadrupole mass spectrometer
• Rxi-5Sil MS GC column (30 m × 0.25 mm i.d., 0.25 µm film)
• PSA, C18, GCB, and MgSO₄ sorbents for QuEChERS cleanup

Reference

• [1] Tobacco Board, Exports Performance during 2013–14, Ministry of Commerce and Industry, Government of India, 2014.
• [2] CORESTA Guide No. 1: Concept and Implementation of CPA Guidance Residue Levels, 3rd Issue, July 2013.
• [3] Zareen S. Khan et al., QuEChERS Extraction for Pesticide Analysis, Journal of Chromatography A, vol. 1343, 2014.