Disinfection by-products and standard anions according to EPA 300.1 A & B on 930 Compact IC Flex

Importance of the Topic

Reliable monitoring of inorganic anions and disinfection by-products is essential to ensure drinking water safety and regulatory compliance. The simultaneous determination of both standard anions (fluoride, chloride, nitrate, sulfate) and oxyhalides (bromide, chlorite, bromate, chlorate) according to EPA Method 300.1 parts A and B reduces analysis time, minimizes sample handling, and supports high‐throughput laboratories in environmental monitoring, quality assurance, and process control.

Objectives and Study Overview

This application note demonstrates a single‐run ion chromatography (IC) method on the 930 Compact IC Flex system coupled with inline ultrafiltration to separate and quantify eight inorganic species in tap water. The approach aims to meet EPA 300.1 A & B requirements, deliver reproducible results at low microgram per liter levels, and simplify pretreatment by integrating filtration during analysis.

Methodology and Used Instrumentation

A direct injection workflow was implemented using inline ultrafiltration to remove particulates prior to separation. Key instrumentation and components include:

• 930 Compact IC Flex with integrated oven, suppressor, pump, and conductivity detector
• 858 Professional Sample Processor for automated sample handling
• IC Equipment for Ultrafiltration module
• Columns: Metrosep A Supp 7 (250×4.0 mm) and Metrosep RP 2 Guard

Eluent consisted of 3.6 mmol/L sodium carbonate; suppressor regenerant was 100 mmol/L sulfuric acid, with STREAM rinsing. Operating conditions: flow rate 0.7 mL/min, injection volume 100 µL, column temperature 50 °C, maximum pressure 15 MPa, run time 40 min.

Main Results and Discussion

Tap water spiked with 5 µg/L of each oxyhalide yielded the following findings:

• Oxyhalides: chlorite (0.004 mg/L, RSD 6.7%), bromide (0.004 mg/L, RSD 2.1%), bromate (0.006 mg/L, RSD 6.0%), chlorate (0.006 mg/L, RSD 1.9%)
• Standard anions: fluoride (0.065 mg/L, RSD 1.1%), chloride (12.44 mg/L, RSD 0.7%), nitrate (7.91 mg/L, RSD 0.4%), sulfate (3.92 mg/L, RSD 0.3%)

These results demonstrate low detection limits, high precision across all targets, and clear separation of closely eluting species within a 40‐minute runtime.

Benefits and Practical Applications

This unified method offers laboratories a fast, robust solution for regulatory compliance testing and routine water analysis. Inline ultrafiltration reduces sample preparation steps and risk of column contamination. Sequential suppression with conductivity detection ensures sensitive measurement of a broad range of anions and oxyhalides.

Future Trends and Potential Uses

Advances in hyphenating IC with mass spectrometry could further lower detection limits and enable structural confirmation of unknown disinfection by-products. Increased automation and online monitoring platforms will support real‐time water quality surveillance. Miniaturized flow systems and green eluent strategies may enhance sustainability and reduce reagent consumption.

Conclusion

The described IC method on the 930 Compact IC Flex provides a comprehensive, accurate, and efficient approach for simultaneous analysis of standard anions and disinfection by-products in water. It meets EPA 300.1 standards and streamlines laboratory workflows.

References

Metrohm IC Application Note S-312, Version 1