The Science of Purity: Modernizing Residue After Evaporation (RAE) Testing

JINAN, China - Dec. 28, 2025 - PRLog -- As global regulators tighten safety requirements for food and medical packaging, a foundational scientific method is undergoing a high-tech transformation. Residue After Evaporation (RAE) testing—a cornerstone of chemical purity for decades—is moving from manual laboratory beakers to fully automated, high-precision systems to meet the rigorous demands of modern safety standards.

What is RAE?

Residue After Evaporation (also known as Non-Volatile Matter or Total Migration) refers to the substances remaining after a liquid sample—such as water, chemical reagents, or food simulants—is completely evaporated and dried.

Rooted in Gravimetric Analysis, RAE is a classical technique based on the physical law of conservation of mass. Unlike electronic sensors, it provides a direct, physical measurement of purity.

The Safety Gatekeeper: Why It Matters

The test quantifies non-volatile substances (monomers, additives, or contaminants) that can leach from packaging into products. It serves as a critical safety barrier in several key industries:

• Food Packaging: Measures "Total Migration" to ensure plastic films and containers don't contaminate food. (Standards: EN 1186, FDA 21 CFR, GB 31604.8)
• Pharmaceuticals: Verifies the purity of IV bags, tubing, and purified water to prevent harmful extracts from entering the bloodstream. (Standards: USP <661>, European Pharmacopoeia)
• Medical Devices: Ensures the safety of plastics used for blood storage and medical delivery. (Standards: ISO 1135, ISO 3826)
• Chemical Industry: Confirms the purity of industrial reagents and solvents. (Standards: ISO 759, ASTM D1353)

Evolution of the Method: Manual to Automated

The Traditional Process

Historically, RAE was a labor-intensive, multi-step manual process:

1. Preparation: Placing a sample in a pre-weighed container.
2. Evaporation: Heating the liquid until volatile components vanish.
3. Drying: Using an oven to reach a "constant weight."
4. Weighing: Using a microbalance to find the final mass.
5. Calculation: Subtracting the initial weight to find the residue mass.

The Next-Gen Shift

Traditional methods are prone to human error and environmental contamination. Modern systems, such as the Labthink C840H, integrate evaporation, drying, and weighing into a single closed-loop environment.

By utilizing high-precision analytical balances (repeatability of 0.01 mg) and removing manual handling, these automated systems (e.g. Labthink Integrated Purity Analysis Systems) ensure sub-milligram accuracy and full compliance with tightened international regulations.

Note: Labthink is a leading multinational technology company specializing in the development and manufacturing of precision instruments and testing solutions for packaging materials analysis. Visit www.labthink.com for more information.