TOC Analysis for Standard Methods 5310B: High-Temperature Combustion Method

Importance of the Topic

The measurement of total organic carbon (TOC) provides a rapid indicator of organic contamination in both drinking water and wastewater. Controlling TOC levels is essential for minimizing disinfection by-product formation and for regulatory compliance in water treatment operations.

Objectives and Overview

This study presents the application of the High-Temperature Combustion Method (Standard Methods 5310B) using a Shimadzu TOC-L analyzer. It aims to demonstrate method performance across a broad concentration range, establish calibration strategies, and validate precision, accuracy, and detection limits.

Used Instrumentation

• Shimadzu TOC-L total organic carbon analyzer
• High-temperature catalytic oxidation furnace (680 °C) with platinum catalyst
• Non-dispersive infrared (NDIR) detector for CO2 measurement
• CO2-free purge gas supply

Methodology

Sample preparation involves acidification to remove inorganic carbon (carbonate and bicarbonate) by converting it to CO2, which is purged from the sample. The remaining organic carbon is oxidized to CO2 and H2O in a platinum-catalyzed furnace at 680 °C. The CO2 produced is measured by NDIR detection. Calibration was performed using potassium hydrogen phthalate (KHP) stock solutions at 1000 ppm, from which two curves were generated (1 ppm to 10 ppm for drinking water, 1 ppm to 100 ppm for wastewater) with auto-dilution.

Results and Discussion

Both calibration curves exhibit excellent linearity (r > 0.9998) and low detection limits (0.03–0.04 ppm). Precision and accuracy were confirmed with check standards: recoveries of 100.8% at 5 ppm (drinking water) and 101.2% at 50 ppm (wastewater), with relative standard deviations below 1.6%. The system handles low-level (ppb) and high-level (ppm) analyses through automatic dilution and multiple calibration options, ensuring reliable performance across diverse matrices.

Benefits and Practical Applications

• Rapid and non-specific detection of total organic content
• Regulatory compliance for drinking water TOC removal and wastewater discharge
• Surrogate measurement for BOD and COD in wastewater
• Automated calibration and dilution simplify routine analysis

Future Trends and Opportunities

Integration of online TOC analyzers for real-time monitoring, coupling with advanced data analytics for process control, development of miniaturized field-deployable units, and combination with other detectors for species-specific analysis represent emerging directions.

Conclusion

The Shimadzu TOC-L analyzer effectively implements Standard Methods 5310B for high-temperature combustion TOC analysis, offering robust performance, broad dynamic range, and streamlined automation for water and wastewater monitoring.

Reference

• Standard Methods for the Examination of Water and Wastewater, Method 5310B: High-Temperature Combustion for Total Organic Carbon Analysis