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[求助]
国外标准-食品级磷酸标准（以湿法酸为原料）
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国外标准-食品级磷酸标准（以湿法酸为原料），主要是美国，日本的国家标准。 以湿法酸为原料，净化得到的食品级磷酸，由于其来源不同，所含杂质不同，因此，制订的标准也应不同。我国暂未制订。 |
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youngdejian(金币+1,VIP+0):谢谢支持！你给的是什么呀？类似于我们的百科？不是标准啊！
youngdejian(金币+1,VIP+0):谢谢支持！你给的是什么呀？类似于我们的百科？不是标准啊！
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USP29 Phosphoric Acid H3PO4 98.00 Phosphoric acid. Phosphoric acid [7664-38-2]. » Phosphoric Acid contains not less than 85.0 percent and not more than 88.0 percent, by weight, of H3PO4. Caution—Avoid contact, as Phosphoric Acid rapidly destroys tissues. Packaging and storage— Preserve in tight containers. Identification— When carefully neutralized with 1 N sodium hydroxide, phenolphthalein TS being used as the indicator, it responds to the tests for Phosphate 191. Sulfate 221— Dilute 6 mL of Phosphoric Acid with 90 mL of water, and add 1 mL of barium chloride TS: no precipitate is formed immediately. Heavy metals, Method I 231: 0.001%. Alkali phosphates— Transfer 1 mL of it to a graduated cylinder, and add 6 mL of ether and 2 mL of alcohol: no turbidity is produced. Limit of nitrate— Dilute 6 mL of Phosphoric Acid with 14 mL of water, mix 5 mL of the dilution with about 0.1 mL of indigo carmine TS, then add 5 mL of sulfuric acid: the blue color is not discharged within 1 minute. Phosphorous or hypophosphorous acid— Dilute 6 mL of Phosphoric Acid with 14 mL of water. Gently warm 5 mL of the dilution, and add 2 mL of silver nitrate TS: the mixture does not become brownish. Residual solvents 467: meets the requirements. (Official January 1, 2007) Assay— Weigh accurately about 1 g of Phosphoric Acid in a tared, glass-stoppered flask, and dilute it with water to about 120 mL. Add 0.5 mL of thymolphthalein TS, and titrate with 1 N sodium hydroxide VS to the first appearance of a blue color. Perform a blank determination, and make any necessary correction. Each mL of 1 N sodium hydroxide is equivalent to 49.00 mg of H3PO4. |
2楼2007-12-23 14:58:21
