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Related to phenolphthalein: methyl orange
a cathartic and pH indicator.
A hydrogen ion indicator obtained by the action of phenol on phthalic anhydride; formerly used as a laxative.
phenolphthalein/phe·nol·phthal·ein/ (fe″nol-thal´ēn) a cathartic and pH indicator, with a range of 8.5 to 9.0.
phenolphthalein(fē′nōl-thăl′ēn′, -thăl′ē-ĭn, -thā′lēn′, -thā′lē-ĭn)
A white or pale yellow crystalline powder, C20H14O4, used as an acid-base indicator, in making dyes, and formerly in medicine as an over-the-counter laxative.
1 a cathartic and pH indicator with a range of 8.5 (colorless) to 9.0 (red).
2 an indicator of hydrogen ion in urine and gastric juice.
1. an acid-base indicator dye; it is colorless below pH 8.5, but turns red above pH 9.0.
2. in monogastric animals, a cathartic administered orally, usually with a bulk laxative such as agar. When ingested by ruminants causes the urine to change color to red on exposure to air.