Ultratrace Tin Speciation with GC-ICP-MS using the Thermo Scientific GCI 100 Interface

Importance of the Topic

Environmental and health risk assessment of tin requires not only total concentration measurements but also identification of specific organotin species. Different tin compounds vary widely in toxicity and persistence, making accurate speciation essential for compliance with regulatory limits and for understanding bioavailability in aquatic systems.

Study Objectives and Overview

This study aimed to establish a robust, high-throughput analytical workflow for ultratrace quantification of organotin species in water. The method couples gas chromatography for separation with inductively coupled plasma mass spectrometry for element-specific detection, using the Thermo Scientific GCI 100 Interface to integrate the TRACE 1310 GC and the iCAP RQ ICP-MS.

Methodology and Instrumentation

Sample Preparation and Derivatization

• Organotin standards (TBT, TPT, TPhT) diluted in 1% HCl
• Ethylation reaction with sodium tetraethylborate and hexane extraction
• Pre-concentration in hexane phase

Instrument Configuration

• Gas Chromatograph: TRACE 1310 GC with TriPlus RSH autosampler
• Interface: Thermo Scientific GCI 100 for GC-ICP-MS coupling
• Mass Spectrometer: iCAP RQ ICP-MS, RF power 1550 W, Pt-tipped sampler/skimmer
• Column: TG-5 MS (30 m × 0.25 mm × 0.25 µm)
• Oven Program: 60 °C (1 min), ramp 50 °C/min to 300 °C, hold 9.2 min
• Injector: Splitless, 1 µL injection at 300 °C
• Carrier Gas: He at 2.2 mL/min; septum purge 5 mL/min; purge flow 10 mL/min
• Transfer Line: 300 °C, Ar makeup 0.9 L/min
• Data System: Qtegra ISDS with ChromControl and tQuant evaluation

Results and Discussion

Chromatograms exhibited sharp, Gaussian peaks for TBT, TPT and TPhT without need for post-acquisition smoothing. Baseline separation was achieved at transfer-line temperatures up to 300 °C. Signal-to-noise ratios exceeded 55 000 for 0.1 ng/mL TBT injections. Calibration across 0.02–10 ng/mL showed linearity (R² > 0.999) and mean residuals below 2%. Limits of detection, calculated as three times the standard deviation of the blank (ICH Q2(R1)), were 0.33 ng/L (TBT), 0.28 ng/L (TPT) and 0.38 ng/L (TPhT), meeting and exceeding European Water Framework Directive requirements (MAC 1.5 ng/L). Automated sequence runs (>40 samples over 10 h) demonstrated system stability and unattended reliability.

Benefits and Practical Applications

The integrated GC-ICP-MS configuration offers:

• Ultralow detection limits in the picogram to nanogram per liter range
• Reproducible baseline separation of organotin species
• High sample throughput with automated control of GC, interface and ICP-MS in one software environment
• Compliance with stringent environmental regulations for antifouling agents

Future Trends and Opportunities

Advances may include improved on-line pre-concentration techniques, expansion to other trace metal speciation, portable GC-ICP-MS setups for field monitoring, and integration of machine-learning algorithms for real-time data evaluation. Further miniaturization and flow-injection approaches could broaden applications to complex matrices such as sediments or biota extracts.

Conclusion

The Thermo Scientific GCI 100 Interface enables seamless GC-ICP-MS coupling for ultratrace organotin speciation. The method delivers robust, sensitive and fully automated analysis, fulfilling regulatory demands and boosting laboratory productivity for environmental monitoring.

References

1. European Water Framework Directive (EWFD), Council Directive 2000/60/EC.
2. ICH Q2(R1) Validation of Analytical Procedures: Text and Methodology.