Online analysis of trace anions in power plant water matrices

Importance of the Topic

Continuous monitoring of ionic contaminants in power plant water is essential for protecting equipment from corrosion, scaling and fouling. Online sampling coupled with automated inline sample preparation ensures reliable, contamination-free analysis and supports real-time decision making in industrial water management.

Objectives and Study Overview

This application note describes a method for simultaneous determination of anions and cations in boiler water using an automated inline sample preparation technique (MiPCT). The goal is to achieve variable preconcentration, single-standard calibration, and stable long-term performance for key ionic species in power plant water.

Methodology and Instrumentation

An inline preconcentration method (MiPCT) provides a 40× enrichment of analytes prior to separation. Calibration is performed using a multi-ion standard at seven levels (0.5–20 µg/L) by varying injection volumes from 50 µL to 2000 µL.

• Columns: Metrosep A Supp 5 150/4.0, Metrosep A Supp 4/5 Guard/4.0, Metrosep A PCC 1 HC/4.0
• Eluent (inline prepared): 6.4 mmol/L Na₂CO₃ and 2.0 mmol/L NaHCO₃
• Suppressor regenerant: 100 mmol/L H₂SO₄
• Flow rate: 0.7 mL/min, Injection volume: 2000 µL
• Operational parameters: Pmax 15 MPa, Column temperature 32 °C, Total runtime 18 min

Used Instrumentation

• 850 Professional IC AnCat – MCS
• 2× IC Conductivity Detector
• 2× 872 Extension Module Liquid Handling
• 2× 800 Dosino (liquid handling)
• 849 Level Control for Inline Eluent Preparation

Main Results and Discussion

Stability testing over 72 hours using an artificial boiler water standard showed consistent concentrations and acceptable repeatability:

• Fluoride: 1.99 µg/L, RSD 4.1 %
• Chloride: 1.99 µg/L, RSD 1.2 %
• Sulfate: 2.04 µg/L, RSD 8.7 %
• Chromate: 1.98 µg/L, RSD 5.2 %

The inline preconcentration maintained sensitivity and precision across multiple analytes without manual intervention.

Benefits and Practical Applications

Automated inline preconcentration and calibration simplify routine monitoring of power plant water, reduce reagent consumption and operator workload, and deliver rapid, reliable data for boiler protection and process control.

Future Trends and Opportunities

Further integration of inline preparation with advanced detectors or mass spectrometry can expand analyte coverage and improve detection limits. Machine-learning algorithms for data evaluation may enhance predictive maintenance and process optimization in industrial water systems.

Conclusion

The described IC method demonstrates robust, simultaneous anion/cation analysis with inline sample preparation, offering high sensitivity, stability and automation suitable for power plant water monitoring.

Reference

IC Application Note Q–5, Version 1