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Storage, transportation and pharmacopoeia information of benzoic acid

Benzoic acid storage

Storage and transportation of benzoic acid:

Flake or powdered benzoic acid can be packed in bags or barrels. If used as a food additive, it should be packed in barrels lined with food-grade plastic bags and paper bags. Stored in a dry warehouse, the packaging must be tight to prevent it from getting damp and deteriorating and to prevent contamination by harmful substances. Molten benzoic acid can be stored in a heated thermos. Water should be prevented from entering during storage, and molten benzoic acid must be transported in trucks equipped with heated insulated tanks.

It is required that benzoic acid should contain no less than 99.0% C7H6O2.

Traits

This product is white and mercerized scales or needle-like crystals or crystalline powder. It is light, odorless or slightly odorless. It is slightly volatile in hot air and has an acidic reaction in aqueous solution.

This product is easily soluble in ethanol, chloroform or ether, soluble in boiling water, and slightly soluble in water.

melting point

The melting point of this product (General Chapter 0612) is 121~124.5℃.

identify

1. Take about 0.2g of this product, add 15mL of 0.4% sodium hydroxide solution, shake and filter. Add 2 drops of ferric chloride test solution to the filtrate to form an ocher precipitate.

2. The infrared light absorption spectrum of this product should be consistent with the control spectrum.

examine

Clarity and color of ethanol solution

Take 5.0g of this product, dissolve it in ethanol and dilute it to 100mL. The solution should be clear and colorless.

Halides and Halogens

Measured according to UV-visible spectrophotometry (General Chapter 0401), the glass instruments used in this experiment must be soaked in 500g/L nitric acid solution overnight before use, washed with water, and then filled with water to ensure that there is no chlorine element.

Solution A: Take 6.7g of this product and place it in a 100mL measuring flask, add 40mL of 1mol/L sodium hydroxide solution and 50mL of ethanol to dissolve, dilute to the mark with water, and shake well. Take 10 mL of the above solution, add 7.5 mL of 2 mol/L sodium hydroxide solution and 0.125 g of nickel-aluminum alloy, heat it on a water bath for 10 minutes, let it cool, and filter. The filtrate is placed in a 25 mL measuring bottle, and the filter residue is washed three times with ethanol. 2 mL at a time, the washing solution was merged into the filtrate, and diluted to volume with water.

Solution B: Blank solution. The preparation method is the same as solution A.

Standard chloride solution: Precisely measure 1 mL of 0.132% (W/V) sodium chloride solution, place it in a 100 mL measuring bottle, and dilute to the mark with water. New system for temporary use.

Ferric sulfate solution: Take 30g of ferric ammonium sulfate, add 40mL of nitric acid and shake, dilute to 100mL with water, filter, and take the filtrate. Keep away from light.

Mercury thiocyanate solution: Take 0.3g of mercury thiocyanate, add absolute ethanol and dissolve it to make 100ml. Use within 7 days after preparation.

Determination method: Take 10 mL each of solution A, solution B, standard chloride solution and water, put them into 25 mL measuring bottles respectively, add 5 mL of ferric sulfate to each solution, shake well, add 2 mL of nitric acid dropwise (shake while adding), and then Add 5 mL of mercury thiocyanate solution to each solution, shake, dilute to volume with water, and place in a 20°C water bath for 15 minutes. Measure the absorbance of solution A (using solution B as the blank) and the standard chloride solution (using water as the blank) at the wavelength of 460 nm.

Limit: The absorbance of solution A must not be greater than the absorbance of standard chloride solution (0.03%).

Easy to oxidize

Take 100mL of water, add 1.5mL of sulfuric acid, boil, add an appropriate amount of potassium permanganate titrant (0.02mol/L) dropwise, until the pink color appears and does not disappear for 30 seconds, add 1.0g of this product while it is hot, and dissolve , add 0.25mL of potassium permanganate titrant (0.02mol/L), it should appear pink and not disappear within 15 seconds.

easy carbide

Take 0.50g of this product, add 5mL of sulfuric acid [containing H2SO4 94.5%~95.5% (g/g)] and shake, leave it for 5 minutes, and compare it with the yellow No. 2 standard colorimetric solution. It should not be darker.

Residue on ignition

Must not exceed 0.1% (General Rule 0841).

heavy metal

Take 1.0g of this product, add 22mL of ethanol to dissolve it, add 2mL of acetate buffer (pH 3.5) and an appropriate amount of water to make 25mL. Check according to the law (General Principle 0821 Method 1). The heavy metal content must not exceed parts per million. ten.

Content determination

Take about 0.25g of this product, weigh it accurately, add 25mL of neutral dilute ethanol (neutral to phenolphthalein indicator solution) to dissolve, add 3 drops of phenolphthalein indicator solution, and titrate with sodium hydroxide titrant (0.1mol/L). Each 1mL of sodium hydroxide titrant (0.1mol/L) is equivalent to 12.21mg of C7H6O2.

category

Disinfectant and antiseptic.

storage

Keep sealed.

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