Environmental ion chromatography

Importance of the Topic

With increasing pressure on water resources and tighter regulatory limits for inorganic ions, disinfection byproducts, and emerging contaminants, high-performance ion chromatography (IC) has become an indispensable tool in environmental analysis. IC offers the sensitivity, selectivity, and throughput needed for routine compliance monitoring, risk assessment, and water-treatment optimization, addressing requirements from global bodies such as the U.S. EPA, ISO, and the European Commission.

Objectives and Study Overview

This compendium of application notes presents a suite of IC-based workflows for the determination of a broad range of analytes in environmental matrices—surface and ground waters, drinking water, wastewater, airborne particles (PM2.5), and industrial discharges. Key goals include:

• Compliance with U.S. EPA Methods 300.0/300.1 for inorganic anions.
• Low-level detection of oxyhalide disinfection byproducts (chlorite, chlorate, bromate) in treated waters.
• Speciation of chromium(III) vs. chromium(VI) and metal cyanide complexes.
• Assessment of adsorbable organic halogens (AOX) and non-targeted PFAS screening.
• Simultaneous determination of haloacetic acids, dalapon, polar pesticides, and saccharides in complex matrices.

Methodology and Instrumentation

Analytical platforms employ Thermo Fisher Scientific’s RFIC™ systems with on-demand eluent generation, compact single-channel Easion™ IC, high-pressure ICS-5000/ICS-6000 HPIC, and Integrion™ HPIC instruments. Separation uses a range of Dionex™ IonPac™ and CarboPac™ columns (AS4A, AS22-Fast-4 µm, AS29-Fast-4 µm, AS19-4 µm, AS23-4 µm, AS27/AS30, AG18/AG19-Fast-4 µm, CS16, AG7, AS11-HC, AS16-4 µm, MA1). Detection modes include suppressed conductivity (AERS™, CRD™, Dionex ASRS™), UV absorbance (352 nm post-column iodide reaction), pulsed amperometry (PAD), and mass spectrometry (single quadrupole, IC-MS, IC-MS/MS, high-resolution Orbitrap™ Q Exactive™ HF, and ICP-MS). Automated sample preconcentration and two-dimensional IC are applied for trace bromate and AOX/AOF measurements.

Main Results and Discussion

IC methods achieved linear calibrations through regulatory ranges, with coefficients of determination (r2) ≥ 0.995. Method detection limits (MDLs) ranged from sub-µg/L for oxyhalides, chromium(VI), and perchlorate to low ng/L for haloacetic acids by IC-MS/MS. Recoveries of spiked anions, cations, and disinfection byproducts in real samples were 90–110%. IC-MS/MS and IC-HRAM workflows delivered lower MDLs and unambiguous analyte identification in high ionic strength waters. Two-dimensional IC suppressed matrix effects for bromate determination down to 0.036 µg/L. Combustion IC quantified AOX in wastewater with recoveries of 98–105%, and a complementary AOF-CIC screening approach identified PFAS-related fluorine burdens. HPAE-PAD resolved 11 saccharide markers in aerosol samples within 55 min and sugar alcohols in < 20 min.

Benefits and Practical Applications

These IC approaches enable:

• Regulatory compliance for drinking water (SDWA, NPDWR, EU Drinking Water Directive) and wastewater permits (NPDES, CWA).
• Routine monitoring of inorganic ions (fluoride, chloride, nitrate, sulfate, lithium, sodium, ammonium, etc.) for treatment optimization.
• Trace speciation of toxic contaminants (Cr(VI), chromate, cyanide complexes) for risk assessment.
• Direct, derivatization-free IC-MS/MS analysis of haloacetic acids, polar pesticides, and herbicides (glyphosate, AMPA, endothall).
• Fast screening of AOX/AOF and PFAS to prioritize samples for advanced LC-MS or GC-MS analysis.
• Source apportionment of biomass burning vs. biogenic aerosol contributions via saccharide markers.

Future Trends and Applications

Emerging directions include coupling IC with high-resolution accurate-mass MS for non-targeted screening of novel disinfection byproducts and emerging pollutants; miniaturized, field-deployable IC systems for real-time monitoring; advanced suppression technologies for enhanced sensitivity; and machine-learning-driven data interpretation for complex environmental datasets.

Conclusion

Thermo Fisher’s comprehensive IC solutions—from RFIC eluent generation to IC-MS/MS and IC-HRAM workflows—address the full range of environmental anions, cations, organic ions, and halogenated contaminants at trace levels. These validated methods deliver robust performance, regulatory compliance, and practical throughput for environmental laboratories in water quality, air monitoring, and industrial analytics.

References

• U.S. EPA Methods 300.0, 300.1, 314.0, 321.8, 332.0, 335.2–335.4, 557
• ISO, ASTM, AWWA standard methods for IC analysis