{"id":2220,"date":"2025-09-22T08:54:43","date_gmt":"2025-09-22T01:54:43","guid":{"rendered":"https:\/\/nhathuocngocanh.com\/bp\/?p=2220"},"modified":"2025-10-03T16:53:38","modified_gmt":"2025-10-03T09:53:38","slug":"aminobenzoic-acid","status":"publish","type":"post","link":"https:\/\/nhathuocngocanh.com\/bp\/aminobenzoic-acid\/","title":{"rendered":"Aminobenzoic Acid"},"content":{"rendered":"

(4-Aminobenzoic Acid, Ph. Eur. monograph 1687)<\/em><\/p>\n

C7<\/sub>H7<\/sub>NO2<\/sub>\u00a0 \u00a0137.1\u00a0 \u00a0150-13-0<\/p>\n

Action and use<\/strong><\/p>\n

Skin protective.<\/p>\n

DEFINITION<\/h2>\n

4-Aminobenzoic acid.<\/p>\n

Content<\/h3>\n

99.0 per cent to 101.0 per cent (anhydrous substance).<\/p>\n

CHARACTERS<\/h2>\n

Appearance<\/h2>\n

White or slightly yellow, crystalline powder.<\/p>\n

Solubility<\/h3>\n

Slightly soluble in water, freely soluble in ethanol (96 per cent). It dissolves in dilute solutions of alkali hydroxides.<\/p>\n

IDENTIFICATION<\/h2>\n

First identification: B.<\/p>\n

Second identification: A, C.<\/p>\n

A. Melting point (2.2.14): 186 \u00b0C to 189 \u00b0C.<\/p>\n

B. Infrared absorption spectrophotometry (2.2.24).<\/p>\n

Comparison 4-aminobenzoic acid CRS.<\/p>\n

C. Thin-layer chromatography (2.2.27).<\/p>\n

Test solution: Dissolve 20 mg of the substance to be examined in methanol R and dilute to 20 mL with the same solvent.<\/p>\n

Reference solution (a): Dissolve 20 mg of 4-aminobenzoic acid CRS in methanol R and dilute to 20 mL with the same solvent.<\/p>\n

Reference solution (b): Dissolve 10 mg of 4-nitrobenzoic acid R in 10 mL of reference solution (a).<\/p>\n

Plate: Suitable silica gel with a fluorescent indicator having an optimal intensity at 254 nm as the coating substance.<\/p>\n

Mobile phase: glacial acetic acid R, hexane R, methylene chloride R (5:20:75 V\/V\/V).<\/p>\n

Application: 1 \u03bcL.<\/p>\n

Development: Over a path of 10 cm.<\/p>\n

Drying: In air.<\/p>\n

Detection: Examine in ultraviolet light at 254 nm.<\/p>\n

System suitability: The chromatogram obtained with reference solution (b) shows 2 clearly separated spots.<\/p>\n

Results: The principal spot in the chromatogram obtained with the test solution is similar in position and size to the principal spot in the chromatogram obtained with reference solution (a).<\/p>\n

TESTS<\/h2>\n

Appearance of solution<\/h3>\n

The solution is clear (2.2.1) and not more intensely coloured than reference solution B5 (2.2.2, Method II).<\/p>\n

Dissolve 1.0 g in ethanol (96 per cent) R and dilute to 20 mL with the same solvent.<\/p>\n

Related substances<\/h3>\n

Liquid chromatography (2.2.29).<\/p>\n

Test solution: Dissolve 25.0 mg of the substance to be examined in the mobile phase and dilute to 100.0 mL with the mobile phase.<\/p>\n

Reference solution: Dissolve 25.0 mg of 4-nitrobenzoic acid R and 25.0 mg of benzocaine R in methanol R and dilute to 100.0 mL with the same solvent. Dilute 1.0 mL to 50.0 mL with the mobile phase. Dilute 1.0 mL of this solution to 10.0 mL with the mobile phase.<\/p>\n

Column:<\/p>\n

\u2014 size: l = 0.12 m, \u00d8 = 4.0 mm,<\/p>\n

\u2014 stationary phase: octylsilyl silica gel for chromatography R (5 \u03bcm).<\/p>\n

Mobile phase: Mix 20 volumes of a mixture of 70 volumes of acetonitrile R and 80 volumes of methanol R, and 80 volumes of a solution containing 1.5 g\/L of potassium dihydrogen phosphate R and 2.5 g\/L of sodium octanesulfonate R adjusted to pH 2.2 with phosphoric acid R.<\/p>\n

Flow rate: 1.0 mL\/min.<\/p>\n

Detection: Spectrophotometer at 270 nm.<\/p>\n

Injection: 20 \u03bcL.<\/p>\n

Run time: 11 times the retention time of 4-aminobenzoic acid.<\/p>\n

Relative retention: With reference to 4-aminobenzoic acid (retention time = about 3 min): impurity A = about 4; impurity B = about 9.<\/p>\n

Limits:<\/p>\n

\u2014 impurity A: not more than the area of the corresponding peak in the chromatogram obtained with the reference solution (0.2 per cent),<\/p>\n

\u2014 impurity B: not more than the area of the corresponding peak in the chromatogram obtained with the reference solution (0.2 per cent),<\/p>\n

\u2014 any other impurity: not more than 0.5 times the area of the peak due to impurity A in the chromatogram obtained with the reference solution (0.1 per cent),<\/p>\n

\u2014 total: not more than 2.5 times the area of the peak due to impurity A in the chromatogram obtained with the
\nreference solution (0.5 per cent),<\/p>\n

\u2014 disregard limit: 0.1 times the area of the peak due to impurity A in the chromatogram obtained with the reference solution (0.02 per cent).<\/p>\n

Impurity C and impurity D<\/h3>\n

Gas chromatography (2.2.28).<\/p>\n

Internal standard solution: Dissolve 20.0 mg of lauric acid R in methylene chloride R and dilute to 100.0 mL with the same solvent.<\/p>\n

Test solution: Dissolve 1.000 g of the substance to be examined in 10.0 mL of an 84 g\/L solution of sodium hydroxide R and extract with 2 quantities, each of 10 mL, of methylene chloride R. Combine and wash with 5 mL of water R; filter through anhydrous sodium sulfate R. Wash the filter with methylene chloride R. Evaporate in a water-bath at 50-60 \u00b0C to obtain a volume of about 1-5 mL. Add 1.0 mL of the internal standard solution and dilute to 10.0 mL with methylene chloride R.<\/p>\n

Reference solution (a): Dissolve 20.0 mg of aniline R in methylene chloride R and dilute to 100.0 mL with the same solvent.<\/p>\n

Reference solution (b): Dissolve 20.0 mg of p-toluidine R in methylene chloride R and dilute to 100.0 mL with the same solvent.<\/p>\n

Reference solution (c): Dilute 0.50 mL of reference solution (a), 0.50 mL of reference solution (b) and 10.0 mL of the internal standard solution to 100.0 mL with methylene chloride R.<\/p>\n

Column:<\/p>\n

\u2014 material: fused silica,<\/p>\n

\u2014 size: l = 30 m, \u00d8 = 0.32 mm,<\/p>\n

\u2014 stationary phase: phenyl(5)methyl(95)polysiloxane R (film thickness 0.5 \u03bcm).<\/p>\n

Carrier gas helium for chromatography R.<\/p>\n

Flow rate: 1.0 mL\/min.<\/p>\n

Split ratio: 1:10.<\/p>\n

Temperature:<\/p>\n\n\n\n\n\n\n\n\n
<\/td>\nTime<\/strong><\/p>\n

(min)<\/strong><\/td>\n

Temperature<\/strong><\/p>\n

(\u00b0C)<\/strong><\/td>\n<\/tr>\n

Column<\/td>\n0 – 4<\/td>\n130<\/td>\n<\/tr>\n
<\/td>\n4 – 6.5<\/td>\n130 \u2192 180<\/td>\n<\/tr>\n
<\/td>\n6.5 – 11.5<\/td>\n180<\/td>\n<\/tr>\n
Injection port<\/td>\n<\/td>\n280<\/td>\n<\/tr>\n
Detector<\/td>\n<\/td>\n300<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Detection: Flame ionisation.<\/p>\n

Injection: 2 \u03bcL; inject the test solution and reference solution (c).<\/p>\n

Retention time Internal standard = about 9.5 min.<\/p>\n

Limits:<\/p>\n

\u2014 impurity C: calculate the ratio (R) of the area of the peak due to impurity C to the area of the peak due to the internal standard from the chromatogram obtained with reference solution (c); calculate the ratio of the area of the peak due to impurity C to the area of the peak due to the internal standard from the chromatogram obtained with the test solution: this ratio is not greater than R (10 ppm),<\/p>\n

\u2014 impurity D: calculate the ratio (R) of the area of the peak due to impurity D to the area of the peak due to the
\ninternal standard from the chromatogram obtained with reference solution (c); calculate the ratio of the area of the peak due to impurity D to the area of the peak due to the internal standard from the chromatogram obtained with the test solution: this ratio is not greater than R (10 ppm).<\/p>\n

Iron (2.4.9)<\/h3>\n

Maximum 40 ppm.<\/p>\n

Dissolve 0.250 g in 3 mL of ethanol (96 per cent) R and dilute to 10.0 mL with water R.<\/p>\n

Water (2.5.12)<\/h3>\n

Maximum 0.2 per cent, determined on 1.00 g.<\/p>\n

Sulfated ash (2.4.14)<\/h3>\n

Maximum 0.1 per cent, determined on 1.0 g.<\/p>\n

ASSAY<\/h2>\n

Dissolve 0.100 g with heating in 50 mL of carbon dioxide-free water R. Titrate with 0.1 M sodium hydroxide determining the end-point potentiometrically (2.2.20).<\/p>\n

1 mL of 0.1 M sodium hydroxide is equivalent to 13.71 mg of C7<\/sub>H7<\/sub>NO2<\/sub>.<\/p>\n

STORAGE<\/h2>\n

Protected from light.<\/p>\n

IMPURITIES<\/h2>\n

\"Aminobenzoic<\/p>\n

A. 4-nitrobenzoic acid,<\/p>\n

\"Aminobenzoic<\/p>\n

B. ethyl 4-aminobenzoate (benzocaine),<\/p>\n

\"Aminobenzoic<\/p>\n

C. aniline,<\/p>\n

\"Aminobenzoic<\/p>\n

D. 4-methylaniline (p-toluidine).<\/p>\n","protected":false},"excerpt":{"rendered":"

(4-Aminobenzoic Acid, Ph. Eur. monograph 1687) C7H7NO2\u00a0 \u00a0137.1\u00a0 \u00a0150-13-0 Action and use Skin protective. DEFINITION 4-Aminobenzoic acid. Content 99.0 per cent to 101.0 per cent (anhydrous substance). CHARACTERS Appearance White or slightly yellow, crystalline powder. Solubility Slightly soluble in water, freely soluble in ethanol (96 per cent). It dissolves in dilute solutions of alkali hydroxides….<\/p>\n","protected":false},"author":4,"featured_media":2245,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[174],"tags":[],"class_list":["post-2220","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-medicinal-substances"],"acf":[],"_links":{"self":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/2220","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/comments?post=2220"}],"version-history":[{"count":5,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/2220\/revisions"}],"predecessor-version":[{"id":8659,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/2220\/revisions\/8659"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media\/2245"}],"wp:attachment":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media?parent=2220"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/categories?post=2220"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/tags?post=2220"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}