product description
| Items | Standard | |
| Appearance and smell | White fine needle crystal or white crystalline powder; odorless or almost odorless | |
| Solubility | Freely soluble in ethanol or ether, soluble in boiling water, sparingly soluble in chloroformslightly soluble in water | |
| Melting point | 158～161 ℃ | |
| Identification (1) Color reaction | Violet color is produce | |
| Identification（2）IR-Spectrum | Should be complied with Reference Spectrum (Spectral set 57) | |
| Residue on ignition | ≤0.1% | |
| Heavy metals | ≤10 ppm | |
| Related substances | 4-hydroxybenzoic acid | ≤0.1% |
| 4-hydroxyisophthalic acid | ≤0.05% | |
| Phenol | ≤0.02% | |
| Other impurities | ≤0.05% | |
| Total impurities | ≤0.2% | |
| Assay | ≥99.5% | |