Description

This product is manufactured through a process involving the reaction of sodium silicate with acids (such as hydrochloric acid, sulfuric acid, and phosphoric acid) or salts (including ammonium chloride, ammonium sulfate, and ammonium bicarbonate). This reaction results in the formation of silicic acid precipitate, commonly known as hydrated silicon dioxide. Subsequently, the precipitate is washed with water to eliminate impurities and then dried to obtain the final product.Calculated as the ignited product, the SiO2 content should not be less than 99.0%.

[Characteristics] This product is a white, loose powder.
This product dissolves in hot sodium hydroxide test solution, but does not dissolve in water or dilute hydrochloric acid.
[Identification] Take about 5mg of this product, place it in a platinum crucible, add 200mg of potassium carbonate, mix well, ignite at 600-700℃ for 10 minutes, cool down, add 2ml of water and gently heat to dissolve, slowly add 2ml of ammonium molybdate test solution (take 6.5g of molybdenum acid, add 14ml of water and 14.5ml of concentrated ammonia solution, shake to dissolve, cool down, slowly add to a cooled mixture of 32ml of nitric acid and 40ml of water under stirring, let stand for 48 hours, filter, take the filtrate, and you have obtained) 2ml, the solution appears dark yellow.
[Inspection] Particle size: Take 10g of this product and inspect it according to the particle size and particle size distribution determination method [General Rule 0982, Method 2 (1)]. The amount of the test sample passing through the No. 7 sieve (125μm) should not be less than 85%.
Acidity and Alkalinity: Take 1g of this product, add 20ml of water, shake well, filter, and take the subsequent filtrate. Measure according to the method (General Rule 0631), and the pH value should be between 5.0 and 7.5.
Chloride: Take 0.5g of this product, add 50ml of water, heat and reflux for 2 hours, cool down, add water to make up to 50ml, shake well, filter, take 10ml of the continuous filtrate, check according to the method (General Rule 0801), and compare with a control solution made by dissolving 10.0ml of standard sodium chloride solution. It should not be more concentrated (0.1%).
Sulfate: Take 10ml of the filtrate obtained from the test for chloride, and conduct the test according to the method (General Rule 0802). Compare it with a control solution prepared by dissolving 5.0ml of standard potassium sulfate solution. The concentration of the test solution should not be higher than that of the control solution (0.5%).
Loss on drying: Take this product and dry it at 145℃ for 2 hours. The loss of weight should not exceed 5.0% (General Rule 0831).
Loss on ignition: Take 1.0g of the test sample remaining under the item of loss on drying, weigh it precisely, and ignite it at 1000℃ for 1 hour. The loss of weight should not exceed 8.5% of the weight of the dried product.
Iron salt: Take 0.2g of this product, add 25ml of water, 2ml of hydrochloric acid, and 5 drops of nitric acid, boil for 5 minutes, cool down, filter, wash the filter with a small amount of water, combine the filtrate and washings, add 50mg of ammonium persulfate, dilute with water to 35ml, check according to the method (General Rule 0807), and compare with the control solution made from 3.0ml of standard iron solution. It should not be darker (0.015%).
Heavy metals: Take 3.3g of this product, add 40ml of water and 5ml of hydrochloric acid, heat gently and boil for 15 minutes, cool down, filter, and place the filtrate in a 100ml volumetric flask. Wash the filter with an appropriate amount of water, and add the washings to the volumetric flask. Dilute with water to the mark, shake well, take 20ml, add 1 drop of phenolphthalein indicator solution, add ammonia solution dropwise until it turns light red, add 2ml of acetate buffer solution (pH3.5) and an appropriate amount of water to make up to 25ml, and check according to the method (General Rule 0821, Method 1). The content of heavy metals should not exceed 30 parts per million.
Arsenic salt: Take 20ml of the solution under the heavy metal item, add 5ml of hydrochloric acid, and check according to the method (General Rule 0822, Method 1). It should comply with the specification (0.0003%).
[Content determination] Take 1g of this product, precisely weigh it, place it in a platinum crucible that has been ignited to constant weight at 1000℃, ignite it at 1000℃ for 1 hour, remove it, cool it down, precisely weigh it, moisten the residue with water, add 10ml of hydrofluoric acid dropwise, evaporate it to dryness on a water bath, cool it down, continue to add 10ml of hydrofluoric acid and 0.5ml of sulfuric acid, evaporate it to near dryness on a water bath, move it to an electric stove and slowly heat it until the acid vapor is completely removed, ignite it to constant weight at 1000℃, cool it down, precisely weigh it, and the weight loss is the weight of SiO2 contained in the test sample.
[Category] Pharmaceutical excipients, flow aids, suspension aids, etc.
[Storage] Keep tightly sealed.