A Comparison of GC-ICP-MS and HPLC-ICP-MS for the Analysis of Organotin Compounds

Significance of the Topic

Organotin compounds are widely used in industrial and agricultural applications but pose significant environmental and health risks at trace levels. Accurate speciation analysis is essential for monitoring contamination in water, sediments, seafood, and consumer products. Sensitive, precise, and reliable methods support regulatory compliance, ecological assessment, and public health studies.

Objectives and Overview of the Study

This study evaluates and compares two chromatographic techniques—gas chromatography coupled with inductively coupled plasma mass spectrometry (GC-ICP-MS) and high-performance liquid chromatography coupled with ICP-MS (HPLC-ICP-MS)—for the speciation and quantification of organotin compounds. Key performance metrics include detection limits, analyte range, precision, run time, and sample preparation requirements.

Methodology and Instrumentation

Samples (environmental sediments) were extracted by accelerated solvent extraction (ASE) using sodium acetate/acetic acid in methanol. For GC-ICP-MS, extracts underwent derivatization with sodium tetraethylborate to form volatile species. HPLC-ICP-MS analyses used direct injection without derivatization. Both methods employed isotope dilution mass spectrometry (IDMS) with enriched 117Sn-tributyltin spike to correct for matrix effects and improve precision.

Used Instrumentation

• Agilent 7500i ICP-MS with ShieldTorch interface
• Agilent 6890 GC with G3158A GC-ICP-MS interface
• Agilent 1100 HPLC system with PEEK flow path and C18 column
• Dionex ASE 200 accelerated solvent extractor
• PFA MicroFlow nebulizer and Peltier-cooled spray chamber

Main Results and Discussion

• GC-ICP-MS separated 10–12 organotin species per run; HPLC-ICP-MS resolved 5–6 species.
• GC peak widths (4–6 s) were narrower than HPLC (50–60 s), yielding higher signal-to-noise ratios.
• Adding 5 % O₂ or N₂ to the carrier gas enhanced GC-ICP-MS sensitivity by 9–16× over no gas.
• Detection limits for tributyltin (TBT) were 0.4 ng/mL (no gas), 0.03 ng/mL (5 % O₂), and 0.006 ng/mL (5 % N₂) by GC-ICP-MS, compared to ~3 pg as Sn by HPLC-ICP-MS.
• Both methods produced statistically equivalent TBT quantification in sediment extracts with precision <2 % RSD.

Benefits and Practical Applications of the Method

• HPLC-ICP-MS offers rapid, derivatization-free analysis for routine high-throughput screening.
• GC-ICP-MS provides superior sensitivity and broader speciation capability for ultratrace monitoring.
• IDMS calibration reduces measurement uncertainty and improves interlaboratory comparability.
• Applicable to environmental monitoring, food safety, drinking-water pipe QC, and human biomonitoring.

Future Trends and Potential Applications

Advances may include multi-element speciation in a single run, on-line extraction and preconcentration, coupling with high-resolution MS, and portable ICP-MS systems for in-field monitoring. Development of greener derivatization reagents and miniaturized sample preparation will further streamline workflows.

Conclusion

Both GC-ICP-MS and HPLC-ICP-MS with IDMS calibration are robust tools for organotin speciation. Method selection depends on required analyte coverage, sensitivity, and throughput. HPLC-ICP-MS suits routine analysis with minimal sample prep, while GC-ICP-MS excels at ultratrace detection and comprehensive speciation.

Reference

1. S. Nicklin and M. W. Robson. Applied Organometallic Chemistry, 1988, 2, 487–508.
2. H. Tao et al. Analytical Chemistry, 1999, 71, 4208–4215.
3. J. C. Keithly et al. Human and Ecological Risk Assessment, 1999, 5(2), 337–354.
4. A. Sadiki and D. T. Williams. Chemosphere, 1996, 32(12), 2389–2398.
5. S. Takahashi et al. Environmental Pollution, 1999, 106, 213–218.
6. R. B. Rajendran et al. Analyst, 2000, 125, 1757–1763.
7. J. L. Gomez-Ariza et al. Journal of Chromatography A, 1998, 823, 259–277.
8. I. A. Leal-Granadillo et al. Analytica Chimica Acta, 2000, 423, 21–29.
9. J. P. Snell et al. Journal of Analytical Atomic Spectrometry, 2000, 15(12), 1540–1545.
10. J. R. Encinar et al. Analytical Chemistry, 2002, 74, 270–281.
11. P. G. Sutton et al. Applied Organometallic Chemistry, 2000, 14, 1–10.
12. Agilent Technologies. GC-ICP-MS Interface Technical Note, 5988-3071EN.
13. C. G. Arnold et al. Analytical Chemistry, 1998, 70, 3094–3101.
14. T. Catterick et al. Journal of Analytical Atomic Spectrometry, 1998, 13, 1109.
15. Guidelines for High Accuracy in IDMS, M. Sargent et al., RSC, 2002.