The production process of phosphorous acid involves 8-10 raw materials. Even using the same raw materials, the quality can vary significantly, especially in key indicators such as Fe, Cl, and SO4. These differences lead to varying performance in demanding applications like semiconductors, electronics, and pharmaceuticals. How can the quality of phosphorous acid be identified? Below, we explain from several aspects, including price, raw materials, and technical specifications.

1. Metal Ions: 

Superior grade requirements: PO4≤0.1%, Cl≤0.005%, SO4)≤0.0001%, Heavy Metal≤0.0002%, Fe≤0.001%. Actual measured values are even lower than these technical requirements. In the electronics industry, excessively high levels of certain ions often cause circuit malfunctions.

2. Appearance: 

H3PO3 produced by reputable manufacturers has a bright color, good appearance, and packaging that meets national standards and export requirements. Products from small workshops, on the other hand, have a dark, dull appearance, a strong, pungent odor, and contain many impurities.

3. Raw Materials: 

98% first-grade phosphorous acid is mostly produced from recycled materials such as dimethyl ether, pentanoyl chloride, and propionyl chloride. 99% superior-grade phosphorous acid is generally produced by the hydrolysis of PCl3. The latter results in a higher total content and very good control of other metal ions. It is mostly for export.

4. Price: 

Phosphorous acid priced around 8000 RMB from reputable manufacturers generally has a purity of around 98% and is considered first-grade. Iron ions, chloride ions, and heavy metals meet national standards. There are also products on the market at significantly lower prices, generally produced from recycled industrial wastewater. The content, color, and metal ion content often deviate greatly from national standards, and these are rarely used. Products priced around 13000-18000 RMB are generally high-purity (over 99%) superior-grade products, with total metal ion content meeting export requirements and strict export standards.

There are several methods to judge the quality of phosphorous acid. Price, appearance, test reports, and brand are some commonly used identification methods. Ultimately, the quality of a product depends on the manufacturer's technical capabilities, production processes, reliable production equipment, and sound management system.