Action and use<\/strong><\/p>\n Keratolytic.<\/p>\n Preparations<\/strong><\/p>\n Coal Tar and Salicylic Acid Ointment<\/p>\n Dithranol and Salicylic Acid Ointment<\/p>\n Salicylic Acid Collodion<\/p>\n Salicylic Acid Cream<\/p>\n Salicylic Acid Ointment<\/p>\n Zinc and Salicylic Acid Paste<\/p>\n 2-Hydroxybenzenecarboxylic acid.<\/p>\n 99.0 per cent to 100.5 per cent (dried substance).<\/p>\n White or almost white, crystalline powder or white or colourless, acicular crystals.<\/p>\n Slightly soluble in water, freely soluble in ethanol (96 per cent), sparingly soluble in methylene chloride.<\/p>\n First identification: A, B.<\/p>\n Second identification: A, C.<\/p>\n A. Melting point (2.2.14): 158 \u00b0C to 161 \u00b0C.<\/p>\n B. Infrared absorption spectrophotometry (2.2.24).<\/p>\n Comparison: salicylic acid CRS.<\/p>\n C. Dissolve about 30 mg in 5 mL of 0.05 M sodium hydroxide, neutralise if necessary and dilute to 20 mL with water R. 1 mL of the solution gives reaction (a) of salicylates (2.3.1).<\/p>\n Dissolve 2.5 g in 50 mL of boiling distilled water R, cool and filter.<\/p>\n The solution is clear (2.2.1) and colourless (2.2.2, Method II).<\/p>\n Dissolve 1 g in 10 mL of ethanol (96 per cent) R.<\/p>\n Liquid chromatography (2.2.29).<\/p>\n Test solution: Dissolve 0.50 g of the substance to be examined in the mobile phase and dilute to 100.0 mL with the mobile phase.<\/p>\n Reference solution (a): Dissolve 10 mg of phenol R (impurity C) in the mobile phase and dilute to 100.0 mL with the mobile phase.<\/p>\n Reference solution (b): Dissolve 5 mg of salicylic acid impurity B CRS in the mobile phase and dilute to 20.0 mL with the mobile phase.<\/p>\n Reference solution (c): Dissolve 50 mg of 4-hydroxybenzoic acid R (impurity A) in the mobile phase and dilute to 100.0 mL with the mobile phase.<\/p>\n Reference solution (d): Dilute 1.0 mL of reference solution (a) to 10.0 mL with the mobile phase.<\/p>\n Reference solution (e): Dilute a mixture of 1.0 mL of each of reference solutions (a), (b) and (c) to 10.0 mL with the mobile phase.<\/p>\n Reference solution (f): Dilute a mixture of 0.1 mL of each of reference solutions (a), (b) and (c) to 10.0 mL with the mobile phase.<\/p>\n Column:<\/p>\n \u2014 size: l = 0.15 m, \u00d8 = 4.6 mm;<\/p>\n \u2014 stationary phase: end-capped octadecylsilyl silica gel for chromatography R (5 \u03bcm).<\/p>\n Mobile phase: glacial acetic acid R, methanol R, water R (1:40:60 V\/V\/V).<\/p>\n Flow rate: 0.5 mL\/min.<\/p>\n Detection: Spectrophotometer at 270 nm.<\/p>\n Injection” 10 \u03bcL of the test solution and reference solutions (d), (e) and (f). Relative retention: With reference to impurity C (retention time = about 9.5 min): impurity A = about 0.6; impurity B = about 0.8.<\/p>\n System suitability: Reference solution (e):<\/p>\n \u2014 the 3rd<\/sup> peak in the chromatogram corresponds to the peak due to impurity C in the chromatogram obtained with reference solution (d);<\/p>\n \u2014 resolution: minimum 1.0 between the peaks due to impurities B and C; if necessary, adjust the quantity of acetic acid in the mobile phase.<\/p>\n Limits:<\/p>\n \u2014 impurity A: not more than the area of the corresponding peak in the chromatogram obtained with reference solution (f) (0.1 per cent);<\/p>\n \u2014 impurity B: not more than the area of the corresponding peak in the chromatogram obtained with reference solution (f) (0.05 per cent);<\/p>\n \u2014 impurity C: not more than the area of the corresponding peak in the chromatogram obtained with reference solution (f) (0.02 per cent);<\/p>\n \u2014 unspecified impurities: for each impurity, not more than the area of the peak due to impurity B in the chromatogram obtained with reference solution (f) (0.05 per cent);<\/p>\n \u2014 total: not more than twice the area of the peak due to impurity A in the chromatogram obtained with reference solution (f) (0.2 per cent);<\/p>\n \u2014 disregard limit: 0.3 times the area of the peak due to impurity A in the chromatogram obtained with reference solution (f) (0.03 per cent). Do not disregard the peak due to impurity C.<\/p>\n Maximum 100 ppm.<\/p>\n Dilute 10 mL of solution S to 15 mL with water R.<\/p>\n Maximum 200 ppm.<\/p>\n Dissolve 1.0 g in 5 mL of dimethylformamide R and add 4 mL of water R. Mix thoroughly. Add 0.2 mL of dilute hydrochloric acid R and 0.5 mL of a 25 per cent m\/m solution of barium chloride R. After 15 min any opalescence in the solution is not more intense than that in a standard prepared as follows: to 2 mL of sulfate standard solution (100 ppm SO4) R add 0.2 mL of dilute hydrochloric acid R, 0.5 mL of a 25 per cent m\/m solution of barium chloride R, 3 mL of water R and 5 mL of dimethylformamide R.<\/p>\n Maximum 0.5 per cent, determined on 1.000 g by drying in a desiccator.<\/p>\n Maximum 0.1 per cent, determined on 2.0 g.<\/p>\n Dissolve 0.120 g in 30 mL of ethanol (96 per cent) R and add 20 mL of water R. Titrate with 0.1 M sodium hydroxide, using 0.1 mL of phenol red solution R as indicator.<\/p>\n 1 mL of 0.1 M sodium hydroxide is equivalent to 13.81 mg of C7<\/sub>H6<\/sub>O3<\/sub>.<\/p>\n Protected from light.<\/p>\n Specified impurities A, B, C.<\/p>\n A. 4-hydroxybenzoic acid,<\/p>\n B. 4-hydroxyisophthalic acid,<\/p>\n C. phenol.<\/p>\n","protected":false},"excerpt":{"rendered":" (Ph. Eur. monograph 0366) C7H6O3\u00a0 \u00a0 \u00a0 \u00a0 138.1\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 69-72-7 Action and use Keratolytic. Preparations Coal Tar and Salicylic Acid Ointment Dithranol and Salicylic Acid Ointment Salicylic Acid Collodion Salicylic Acid Cream Salicylic Acid Ointment Zinc and Salicylic Acid Paste DEFINITION 2-Hydroxybenzenecarboxylic acid. Content 99.0 per cent to 100.5 per cent…<\/p>\n","protected":false},"author":2,"featured_media":29130,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[174],"tags":[],"class_list":["post-29114","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\/29114","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\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/comments?post=29114"}],"version-history":[{"count":2,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/29114\/revisions"}],"predecessor-version":[{"id":29135,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/29114\/revisions\/29135"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media\/29130"}],"wp:attachment":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media?parent=29114"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/categories?post=29114"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/tags?post=29114"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}DEFINITION<\/h2>\n
Content<\/h3>\n
CHARACTERS<\/h2>\n
Appearance<\/h3>\n
Solubility<\/h3>\n
IDENTIFICATION<\/h2>\n
TESTS<\/h2>\n
Solution S<\/h3>\n
Appearance of solution<\/h3>\n
Related substances<\/h3>\n
\nIdentification of impurities Use the chromatogram obtained with reference solution (e) to identify the peaks due to impurities A, B and C.<\/p>\nChlorides (2.4.4)<\/h3>\n
Sulfates<\/h3>\n
Loss on drying (2.2.32)<\/h4>\n
Sulfated ash (2.4.14)<\/h4>\n
ASSAY<\/h2>\n
STORAGE<\/h2>\n
IMPURITIES<\/h2>\n
![\"Salicylic](\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/11\/Salicylic-Acid-2-300x163.jpg\")
<\/p>\n![\"Salicylic](\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/11\/Salicylic-Acid-3-300x163.jpg\")
<\/p>\n![\"Salicylic](\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/11\/Salicylic-Acid-4-300x163.jpg\")
<\/p>\n