Analysis of Anions Using Non-Suppressor Ion Chromatograph HIC-NS

Importance of the Topic

Ion chromatography is a vital technique for quantifying anions in various matrices including drinking water, environmental samples, and food products. High sensitivity and selectivity for common anions support regulatory compliance and quality control in water and food industries.

Objectives and Study Overview

This study evaluates the performance of the HIC-NS non-suppressor ion chromatograph paired with the Shim-pack IC-A3 anion column for simultaneous determination of seven anions (fluoride, chloride, nitrite, bromide, nitrate, phosphate, sulfate). The method is applied to tap water, mineral water, plating solution, energy drink, and mouthwash samples.

Methodology

The non-suppressor system eliminates the need for suppressor devices, reducing maintenance and consumable costs. Separation was achieved using a mixed eluent of 8.0 mmol/L p-hydroxybenzoic acid, 3.2 mmol/L Bis-Tris, and 50 mmol/L boric acid at 1.2 mL/min, 40 °C, with 50 µL injections. Detection was performed via conductivity. Calibration employed five-point linear regression over 0.5–20 mg/L for each ion.

Used Instrumentation

• HIC-NS Ion Chromatograph (non-suppressor configuration)
• LC-20Ai pump
• SIL-20AC autosampler
• CTO-40C column oven
• CDD-10AVP conductivity detector
• Shim-pack IC-A3 Analytical Column (250 mm×4.6 mm, 5 µm) and IC-GA3 Guard Column (10 mm×4.6 mm, 5 µm)

Main Results and Discussion

Calibration curves exhibited excellent linearity (r² > 0.999). Repeatability tests (n = 5) yielded area RSDs below 0.03% and LOQs ranging from 0.01 to 0.07 mg/L. Standard mixtures showed clear resolution of all seven anions. The method successfully quantified anions in diluted tap water, mineral water (soft water), plating solutions (5000× dilution), energy drinks (100×), and a mouthwash sample with iodide by adding 5% acetonitrile to the eluent to accelerate iodide retention.

Benefits and Practical Applications

The non-suppressor approach simplifies instrument setup, lowers operating costs, and maintains high sensitivity for routine monitoring of anions in diverse sample types. The flexibility to introduce organic modifiers enables analysis of more hydrophobic ions like iodide.

Future Trends and Opportunities

Emerging directions include coupling with mass spectrometry for enhanced detection, automated online sample preparation, expansion to cation and organic acid analysis, and development of greener eluents. Integration with data analytics platforms will further streamline quality control workflows.

Conclusion

The HIC-NS non-suppressor ion chromatograph coupled with Shim-pack IC-A3 column provides a robust, cost-effective, and versatile solution for high-precision anion analysis across food, environmental, and industrial applications.