外观Appearance 橙色至棕色粉末红外光谱鉴别Infrared spectrometry Conforms纯度Purity ≥98.0% (HPLC area%) 水溶解试验solubility in hot Water 合格水溶解试验solubility in hot EtOH 合格干燥损失Drying loss ≤10.0 %灼烧残渣Ignition residue(Sulfate) 20.0 - 30.0 %(after drying)pH变色域Transition interval(pH) (红黄色)10.0 - 12.0(黄红色)吸光度Absorbance(以干基计) ≤0.320(5 mg/L, pH 9.6, 375.0 nm)