Multi-Residue Pesticide Analysis in Norbixin colour additive oleoresin using GC-MS/MS

Importance of the Topic

Norbixin is a widely used natural carotenoid color additive extracted from Bixa orellana seeds and is present in many food, cosmetic and pharmaceutical products. Due to intensive agricultural practices, residual pesticides can accumulate in oleoresin extracts, posing potential health risks. Accurate multi-residue analysis of pesticide traces in norbixin is therefore critical to ensure product safety, support regulatory compliance and protect consumer health.

Study Objectives and Overview

This work describes the development and validation of a highly sensitive multi-residue pesticide analysis method for norbixin oleoresin, combining a modified QuEChERS sample preparation with triple quadrupole gas chromatography–tandem mass spectrometry (GC-MS/MS). The goal was to achieve low limits of quantification (LOQs), robust recoveries and reproducible precision across more than 50 common pesticide analytes.

Methodology and Instrumentation

Sample preparation employs a modified QuEChERS extraction using acetonitrile, sodium chloride and anhydrous MgSO4, followed by dispersive SPE clean-up with C18, graphitized carbon black and PSA sorbents. Matrix-matched calibration standards at six levels (1–50 ppb) were used to correct matrix effects. Analytical measurements were carried out under optimized GC temperature gradients and multiple reaction monitoring (MRM) transitions for target pesticides. Data processing and automatic method optimization leveraged vendor software to streamline validation.

Instrumentation

• GC-MS/MS system: Shimadzu GCMS-TQ8040 NX
• Auto-injector: AOC-20i +s
• Column: SH-I-5Sil MS (30 m × 0.25 mm i.d., 0.25 µm film)
• Injection mode: Splitless at 250 °C, 2 µL injection volume
• Carrier gas: Helium at 40.4 cm/s
• Ionization: Electron impact, interface 280 °C, ion source 230 °C

Main Results and Discussion

Linearity was demonstrated across 1–50 ppb for all analytes, with correlation coefficients (r²) above 0.97. LOQs of 5 ppb were achieved for 45 pesticides, 10 ppb for 10 compounds and 25 ppb for one degradant. Mean recoveries at LOQ levels ranged between 60 % and 120 %, meeting SANTE guidelines, with repeatability RSD <20 % and within-laboratory reproducibility RSD <30 % for all analytes. The combined method effectively minimized matrix interferences and instrument contamination, enabling trace-level detection even after sample dilution.

Benefits and Practical Applications

This approach offers laboratories a reliable, efficient tool for simultaneous quantification of a broad pesticide panel in a complex natural colorant matrix. High sensitivity and ruggedness reduce false positives and instrument maintenance, supporting routine QA/QC, regulatory monitoring and risk assessment in food and agrochemical industries.

Future Trends and Potential Uses

Advances may include further miniaturization of sample preparation, integration with high-throughput and automated platforms, expansion to additional plant-derived color additives, and coupling with machine-learning algorithms for enhanced data interpretation and rapid screening workflows.

Conclusion

The modified QuEChERS-GC-MS/MS method reliably quantifies multi-class pesticide residues in norbixin oleoresin at low ppb levels, with excellent validation parameters. Its robustness and sensitivity make it well suited for regulatory compliance and safety assurance of natural color additives.

Reference

1. Anastassiades M., Lehotay S. J., Štajnbaher D., Schenck F. J. Fast and Easy Multiresidue Method Employing Acetonitrile Extraction/Partitioning and Dispersive Solid-Phase Extraction for the Determination of Pesticide Residues in Produce. J. AOAC Int., 86:412–431 (2003).
2. European Commission. Guidance document on analytical quality control and method validation procedures for pesticide residues and analysis in food and feed. SANTE/11312/2021.