| Folin's reagent | The reaction of amino acids in alkaline solution with 1,2-naphthoquinone-4-sulfonate (Folin's reagent) to yield a red colour; useful for quantitative assay. Synonym: Folin's reagent. (05 Mar 2000) |
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| Fouchet's reagent | A 25% solution of trichloroacetic acid, containing 0.9% ferric chloride; a drop of the reagent added at the surface line of barium chloride-impregnated filter paper which has been dipped in urine for 10 sec will give a green colour if bilirubin is present. See: Fouchet's stain. (05 Mar 2000) |
| Froehde's reagent | Sodium molybdate 1, in strong sulfuric acid 1000; gives various colour reactions with alkaloids. (05 Mar 2000) |
| Frohn's reagent | Bismuth subnitrate (1.5) and water (20.0) heated to boiling, to which hydrochloric acid (10.0) and potassium iodide (7.0) are added; used to test for alkaloids and for sugar. (05 Mar 2000) |
| Lloyd's reagent | Precipitated aluminum silicate, used in the determination of alkaloids. (05 Mar 2000) |