TOC Evaluation of Sulfuric Acid

Significance of the Topic

Sulfuric acid is a key industrial chemical used in fertilizers, metal refining and semiconductor cleaning. Organic contaminants in acid can impair process efficiency and product quality. Total organic carbon (TOC) measurement serves as a reliable indicator of such impurities and supports quality control in high purity applications.

Objectives and Study Overview

This work illustrates direct TOC analysis of 1 percent sulfuric acid solution using a TOC-L analyzer. The study aims to demonstrate accurate detection of non purgeable organic carbon without interference from high sulfate ion background.

Methodology

A 1 percent sulfuric acid solution was prepared and spiked with potassium hydrogen phthalate to yield TOC levels of 1, 5 and 10 mgC per liter. The non purgeable organic carbon method was applied with sparging for inorganic carbon removal. Calibration used two point standards at 0 and 20 mgC per liter with an origin shift to correct for blank water TOC.

Instrumentation

• TOC-L total organic carbon analyzer
• ASI-L autosampler for automated sample injection
• Standard catalyst for catalytic oxidation

Results and Discussion

Recovery rates ranged from 99.9 to 102 percent across spiked levels, confirming quantitative accuracy. A linear correlation between added and measured TOC showed a coefficient of 0.9999. Results indicate sulfate ions do not interfere under the tested conditions and that reliable detection near 1 mgC per liter is achievable.

Benefits and Practical Applications

• Quality control of sulfuric acid in semiconductor wafer cleaning and fertilizer production
• Rapid assessment of organic impurities to prevent process disruption
• Automated sampling for improved throughput in routine analysis

Future Trends and Potential Applications

Extending direct TOC analysis to higher acid concentrations with optimized dilution protocols Advanced integration of TOC monitoring into continuous process analytics Development of inline sensors based on similar principles for real time impurity tracking

Conclusion

The TOC-L analyzer provides accurate and direct determination of organic carbon in 1 percent sulfuric acid solutions. This method enhances impurity management and supports quality assurance in critical industrial applications.

References

• Jiajie Du Application News TOC Evaluation of Sulfuric Acid First Edition August 2023 Shimadzu Corporation