The quality standard for 2-Phosphonobutane-1,2,4-Tricarboxylic Acid (PBTC) in China is defined by the chemical industry standard HG/T 3662-2010.
Primary Standard: HG/T 3662-2010
This standard, titled “Water treatment chemicals — 2-Phosphonobutane-1,2,4-tricarboxylic acid”, is the currently effective version, having replaced the older HG/T 3662-2000 . It specifies the requirements, test methods, inspection rules, and packaging for PBTC, which is primarily used as a scale and corrosion inhibitor in industrial water treatment .
Key Technical Indicators
The standard defines the quality specifications for the liquid form of PBTC (typically supplied as a 50% active content aqueous solution). The main indicators are as follows :
| Items | Index |
|---|---|
| Appearance | Clear, colorless to pale yellow aqueous solution |
| Active acid, % | 50.0 min |
| Phosphorous acid(as PO33-), % | 0.5 max |
| Phosphoric acid(as PO43-), % | 0.2 max |
| Density (20℃), g/cm3 | 1.27 min |
| pH(1% water solution) | 1.5~2.0 |
| Fe, ppm | 10.0 max |
| Chloride, ppm | 10.0 max |
Comparison with Commercial Specifications
It is worth noting that some commercial suppliers list slightly different or more detailed specifications. For example, some may specify a chloride limit of ≤ 10 ppm and an iron limit of ≤ 5 ppm or ≤ 10 ppm . The values listed in the table above reflect the official HG/T 3662-2010 requirements, which are the authoritative baseline for this product in China.