AUTOMATED EXTRACTION OF FREE BASE AND PROTONATED NICOTINE FROM E-LIQUIDS

Význam tématu

The accurate measurement of free-base and protonated nicotine in e-liquids is mandated by the EU Tobacco Products Directive to ensure safe consumer products and regulatory compliance. Automated workflows can alleviate bottlenecks in high-throughput laboratories and improve data quality by minimizing manual handling errors.

Cíle a přehled studie / článku

This application note evaluates an automated extraction and calibration preparation method for quantifying free-base and protonated nicotine in e-liquids. The study compares performance metrics of the automated GERSTEL MPS robotic platform against conventional manual solvent extraction and gas chromatography-flame ionization detection (GC-FID).

Použitá metodika a instrumentace

The experimental setup includes:

• GERSTEL MultiPurpose Sampler (MPS) RoboticPro with QuickMix and CF200 centrifuge.
• Agilent 7890B GC with FID, DB-Wax column (10 m × 0.25 mm × 0.5 µm), helium carrier gas (0.8 mL/min).
• Injection: 1 µL split 20:1, inlet 280 °C; FID at 280 °C; oven: 40 °C (1 min) to 240 °C at 50 °C/min (hold 2 min).

Workflow highlights:

• Manual calibration: Nine standards prepared in volumetric flasks with dichloromethane (DCM) and internal standard (heptadecane), then aliquoted into GC vials.
• Automated calibration: Standards directly dispensed into GC vials, using full-scale and 10× diluted stocks for low concentrations, with reduced solvent volumes.
• Sample extraction: Two-step liquid–liquid extraction for free-base and protonated nicotine, involving water, DCM, NaOH, mixing, centrifugation, and transfer steps, fully automated except sample vial loading.

Hlavní výsledky a diskuse

Comparison of calibration performance revealed:

• Automated calibration linearity (R² = 0.9997) exceeded manual preparation (R² = 0.9977).
• Internal standard response variability was markedly lower in the automated set (RSD 5.0%) versus manual (RSD 20.2%).

Forty-five replicate extractions of a single e-liquid sample yielded:

• Free-base nicotine: mean 13.33 mg/g, RSD 3.1%.
• Protonated nicotine: mean 5.13 mg/g, RSD 5.8%.
• Total nicotine: mean 18.46 mg/g, RSD 0.6%.

Chromatographic overlays confirmed consistent peak shapes and retention times for both analytes across replicates.

Přínosy a praktické využití metody

The automated method delivers:

• Significant reduction in analyst hands-on time, enabling higher throughput.
• Improved precision and linearity in calibration curves, reducing retests.
• Lower solvent and reagent consumption, cutting costs and waste disposal volumes.
• Enhanced laboratory safety by minimizing analyst exposure to hazardous solvents.

Budoucí trendy a možnosti využití

The modular GERSTEL MPS platform can be further adapted to automate other complex sample preparation workflows. Future improvements in instrument sensitivity may allow even smaller sample and reagent volumes. Integration with laboratory information management systems (LIMS) and advanced robotic grippers could enable fully unattended end-to-end analysis.

Závěr

The automated GERSTEL MPS method for extracting free-base and protonated nicotine from e-liquids, combined with in-vial calibration standard preparation, offers superior linearity, reproducibility, and throughput compared to manual protocols. Laboratories can achieve regulatory compliance more efficiently while reducing costs and improving data quality.

Reference

Application Note AS-240, Anatune Ltd., Automated extraction of free-base and protonated nicotine from e-liquids.