source

This product is 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (1-piperazinyl) -3-quinoline carboxylic acid. Calculated as a dry product, the content of C16H18FN3O3 should be 98.5% to 102.0%.

character

This product is a white to light yellow crystalline powder, odorless, slightly bitter in taste, and has hygroscopicity.

This product is slightly soluble in dimethylformamide, extremely soluble in water or ethanol, and easily soluble in acetic acid, hydrochloric acid, or sodium hydroxide solutions.

melting point

The melting point of this product is 218-224 ℃ (general rule 0612).

distinguish

1. Perform the test using thin layer chromatography (General Rule 0502).

Test solution: Take an appropriate amount of this product and add chloroform methanol (1:1) to make a solution containing 2.5mg per 1mL.

Reference solution: Take an appropriate amount of Norfloxacin reference substance and add chloroform methanol (1:1) to prepare a solution containing 2.5mg per 1mL.

Chromatographic conditions: Using a silica gel G thin layer plate and a chloroform methanol concentrated ammonia solution (15:10:3) as the developing agent.

Determination method: Take 10 µ L of the test solution and 10 µ L of the reference solution, place them on the same thin layer plate, unfold, air dry, and examine under a UV light (365nm).

Result determination: The position and fluorescence of the main spot displayed in the test solution should be the same as that of the control solution.

2. In the chromatogram recorded under the content determination item, the retention time of the main peak of the test solution should be consistent with that of the reference solution.

The above two options 1 and 2 can be chosen as one.

inspect

Clarity of solution

Take 5 portions of this product, each 0.5g, and dissolve them in 10mL of sodium hydroxide test solution. The solution should be clear, and if it shows turbidity, it should not be thicker than the turbidity standard solution No. 2 (General Rule 0902, Method 1).

Related substances

Determine according to the high-performance liquid chromatography method (General Rule 0512).

Test solution: Take an appropriate amount of this product, accurately weigh it, add an appropriate amount of 0.1mol/L hydrochloric acid solution (1mL of 0.1mol/L hydrochloric acid solution per 12.5mg of norfloxacin) to dissolve, and dilute it quantitatively with mobile phase A to make a solution containing approximately 0.15mg per 1mL.

Reference solution: Accurately measure an appropriate amount of the test sample solution and dilute it quantitatively with mobile phase A to produce a solution containing 0.75 µ g per 1mL.

Impurity A reference solution: Take approximately 15mg of Impurity A reference solution, accurately weigh it, place it in a 200mL volumetric flask, add acetonitrile to dissolve and dilute to the mark, shake well, accurately measure an appropriate amount, and quantitatively dilute with mobile phase A to produce a solution containing approximately 0.3 µ g per 1mL.

System suitability solution: Weigh appropriate amounts of norfloxacin reference substance, ciprofloxacin reference substance, and enoxacin reference substance, add an appropriate amount of 0.1mol/L hydrochloric acid solution to dissolve, and dilute with mobile phase A to prepare a mixed solution containing 0.15mg of norfloxacin, 3 µ g of ciprofloxacin, and 3 µ g of enoxacin per 1mL.

Chromatographic conditions: Using octadecylsilane bonded silica gel as the filler, using 0.025mol/L phosphoric acid solution (adjusted to pH 3.0 ± 0.1 with triethylamine) – acetonitrile (87:13) as mobile phase A, acetonitrile as mobile phase B. Linear gradient elution was performed according to the following table, with detection wavelengths of 278nm and 262nm, and injection volume of 20 μ L.