Agilent ICP-MS Journal (December 2016 – Issue 67)

Importance of the Topic

Analytical control of ultra-trace contaminants and isotopic signatures is critical in semiconductor manufacturing, environmental studies, and nanomaterial safety. High-purity processing reagents such as sulfuric acid and hydrogen peroxide must be free of metals at sub-ppt levels to avoid wafer contamination. Sulfur stable isotope ratios in natural waters trace biogeochemical cycles and anthropogenic impacts. Precise measurement of nanoparticles like TiO2 in consumer products supports toxicology and regulatory research.

Objectives and Overview

The December 2016 issue presents three main studies using Agilent 8900 triple quadrupole ICP-QQQ: determination of ultra-trace elements in semiconductor-grade sulfuric acid and hydrogen peroxide; sulfur isotope ratio analysis in mineral waters; and single-particle analysis of TiO2 nanoparticles. Each study aims to push detection limits, simplify workflows, and demonstrate enhanced interference removal compared to conventional ICP-MS.

Methodology and Instrumentation

An Agilent 8900 ICP-QQQ in MS/MS mass-shift mode with reaction gases (NH3, O2, H2) and axial acceleration technology was employed. Key features include a front-end quadrupole (Q1) to select precursor ions, a collision/reaction cell to remove matrix interferences, and a second quadrupole (Q2) to monitor product ions. Samples were prepared via standard addition in tenfold dilutions for sulfuric acid and peroxide, self-aspirated nebulization, and per-particle time-resolved acquisition for nanoparticles. Sulfur isotope measurements used O2 cell gas to form SO+ and bracketing with IAEA standard reference materials to correct mass bias.

Main Results and Discussion

• Ultra-trace element analysis in 9.8% H2SO4 achieved sub-ppt detection limits for 39 of 42 elements, with excellent linearity (R>0.9995) and recoveries within 90–110%. In 35% H2O2, 23 SEMI C30-1110 elements were measured at sub-ppt to single-ppt levels with RSDs <8%.
• Sulfur isotope ratios (34S/32S) were determined in bottled mineral waters, river and spring samples, seawater CRM, and high-purity acids. Results matched known VCDT benchmarks and revealed distinct isotopic signatures among sources.
• Single-particle ICP-QQQ quantified TiO2 nanoparticles in sunscreen matrices, resolving 48Ti against 48Ca interference via MS/MS mass shift to TiO+ at m/z 64. Particle size distributions centered near 36 nm, in agreement with reference anatase standards, even in complex matrices.

Practical Benefits and Applications

• Improved interference removal reduces or eliminates pre-analysis separations.
• Sub-ppt capabilities support semiconductor QA/QC and environmental monitoring.
• Fast isotope ratio workflows require sample dilution only, benefiting geochemistry and hydrology.
• Nanoparticle characterization in consumer products enables safety assessment and regulatory compliance.

Future Trends and Opportunities

Emerging applications include protein quantification for pharmaceutical quality control, expanded speciation methodologies, and routine multi-element screening of increasingly complex matrices. Continued development of cell-gas chemistries, automated workflows, and community training events will drive broader adoption and novel research.

Conclusion

Triple quadrupole ICP-MS (ICP-QQQ) with MS/MS mode delivers unparalleled sensitivity and interference control for ultra-trace element quantification, isotope ratio analysis, and nanoparticle detection. Its robust performance in diverse matrices makes it an essential tool for semiconductor manufacturing, environmental and geochemical research, and nanomaterial safety evaluation.

Reference

• 1. SEMI C30-1110, Specifications for hydrogen peroxide (2010)
• 2. Determination of trace elements in ultrapure semiconductor grade sulfuric acid using the Agilent 8900 ICP-QQQ in MS/MS mode, Agilent publication 5991-7008EN (2016)
• 3. Determination of ultra trace elements in high purity hydrogen peroxide with Agilent 8900 ICP-QQQ, Agilent publication 5991-7701EN (2016)