Nitric and Phosphoric Acid Analysis by Potentiometric Titration

Mixed solutions of nitric acid (HNO₃) and phosphoric acid (H₃PO₄) are widely used in semiconductor manufacturing, metal finishing, glass processing, and chemical production. Maintaining the correct concentration of each acid is essential for consistent etching, cleaning, and surface treatment performance.

Automated potentiometric titration provides a fast, accurate, and repeatable method for determining both nitric acid and phosphoric acid in the same sample. By identifying two distinct endpoints on the titration curve, the concentrations of each acid can be calculated without complex sample preparation. This approach improves laboratory efficiency while delivering reliable process control.

Why Analyze Mixed Acid Solutions?

Routine analysis helps manufacturers:

Maintain consistent process chemistry
Optimize metal surface treatment
Improve semiconductor cleaning performance
Verify bath composition
Reduce chemical waste
Extend bath life
Ensure product quality
Meet process specifications

Recommended Instrument

The COM-A19 Automatic Potentiometric Titrator automates titrant delivery, endpoint detection, calculations, and reporting.

Key benefits include:

Automatic endpoint detection
High analytical precision
Excellent repeatability
Fractional titration capability
Electronic data storage
Reduced operator variability

Principle of the Method

The mixed acid sample is titrated with standardized sodium hydroxide solution while monitoring pH with a glass electrode.

Two distinct inflection points are observed:

First endpoint – total acidity (nitric acid + phosphoric acid)
Second endpoint – phosphoric acid

Using the titration volumes from both endpoints, the instrument automatically calculates the concentration of phosphoric acid, while the nitric acid concentration is obtained by difference. This allows accurate determination of both acids from a single titration.

Typical Applications

This method is commonly used for:

Semiconductor process chemicals
Metal finishing baths
Stainless steel pickling solutions
Glass processing
Chemical manufacturing
Industrial cleaning solutions
Research and development laboratories

Advantages of Automated Potentiometric Titration

Compared with manual titration, automated analysis provides:

Improved precision
Better repeatability
Automatic calculations
Faster analysis
Electronic record keeping
Reduced operator error

Typical Results

The COM-A19 provides:

Automatic endpoint recognition
Accurate determination of nitric acid
Accurate determination of phosphoric acid
Excellent batch-to-batch repeatability
Electronic reporting and data storage

Related Standards

This application is based on established potentiometric acid-base titration principles commonly used for industrial process control and quality assurance. Laboratories should follow their applicable ASTM, ISO, JIS, or internal analytical procedures as required.

Why Choose JM Science?

JM Science has supplied automated titration systems to laboratories throughout North America for more than 22 years. Our COM-A19 Automatic Potentiometric Titrator supports demanding applications in semiconductor manufacturing, metal finishing, chemical processing, pharmaceuticals, and environmental laboratories with reliable performance and expert technical support.