Speciation Applications Summary Ion Chromatography

Importance of Speciation Analysis

Speciation analysis distinguishes chemical forms of elements to assess their different toxicities and biological activities. Ion chromatography coupled with inductively coupled plasma mass spectrometry (IC-ICP-MS) is a powerful hyphenated technique that separates ionic species and provides element-specific detection with sub-ppt sensitivity. Accurate speciation is critical in food safety, environmental monitoring, pharmaceuticals and consumer products where total element concentration alone is insufficient.

Objectives and Study Overview

This compilation reviews application notes and technical notes outlining IC-ICP-MS methods for various analytes such as arsenic, chromium, mercury, bromine, and iodide. The goals are to:

• Separate and quantify inorganic and organic species in complex matrices
• Evaluate method detection limits, recoveries, and regulatory compliance
• Demonstrate instrumental configurations and optimized parameters for routine analysis

Methodology and Instrumentation Used

The core technique combines metal-free ion chromatography systems (Dionex ICS-5000, ICS-6000, IC-1600, ICS-900, Aquion, Integrion, HPIC) with Thermo Scientific iCAP Q, iCAP RQ and iCAP TQ ICP-MS consoles. Key features include:

• Eluent generation for high-purity eluents
• Anion and cation exchange columns (AS7, AS11, CS5A, AS19, AG7, NG1)
• Sensitivity enhancement via collision/reaction cells and kinetic energy discrimination
• Operating parameters such as gradient elution, flow rates (0.3–1.5 mL/min), injection volumes (10–100 µL), and column temperatures
• Detection by conductivity, pulsed amperometric detection, and ICP-MS with optimized dwell times and cell gas flows

Main Results and Discussion

Arsenic speciation in apple juice, brown rice syrup, human urine and rice revealed inorganic species As(III) and As(V) at low ng/g levels, with method detection limits below 0.01 ng/g and recoveries between 94–104%. Chromium speciation in drinking water and toy materials differentiated essential Cr(III) from toxic Cr(VI), achieving recoveries near 99–105% at regulatory levels (<3–10 µg/L). Bromate monitoring in ozonated water met EPA Method 321.8 with detection at 0.3 µg/L and recoveries around 100%. Iodide and iodate in infant formula were quantified with pulsed amperometric detection and conversion protocols. Mercury speciation in herbal medicines and contact lens solutions effectively separated inorganic, methyl and ethylmercury with high spike recoveries and sensitivity down to pg/mL.

Benefits and Practical Applications of the Method

• High sensitivity and element specificity ensure compliance with strict regulations
• Simultaneous multi-species separation reduces analysis time and sample handling
• Metal-free fluidics and eluent generation improve reproducibility and lower maintenance
• Wide dynamic range supports both trace-level monitoring and total concentration screening
• Adaptable to diverse matrices including food, pharmaceuticals, environmental water and consumer products

Future Trends and Potential Applications

The integration of triple quadrupole ICP-MS and novel 4 µm particle HPIC columns will further enhance resolution and interference removal. Automated online sample preparation and miniaturized IC systems can expand field-deployable speciation analysis. Advances in data processing, real-time quality control and coupling with separation techniques like HPLC and capillary electrophoresis are expected to broaden applications in metabolomics, biomonitoring and nanotechnology.

Conclusion

IC-ICP-MS is a versatile platform for comprehensive elemental speciation, delivering rapid, precise and sensitive determination of toxic and essential species. The reviewed methods demonstrate robust performance across multiple analytes and regulatory frameworks, underscoring the importance of chemical speciation in safety and quality control. Continued innovations will expand capabilities and drive adoption in routine and research laboratories.

References

A selection of Thermo Scientific application and technical notes including AN43099, AN43126, TN43357, AN43255, AN43227, AN43098, AN43175, AN37, AN43130 and AN43141.