reagent (re-a´jent)

Any substance added to a solution of another substance to participate in a chemical reaction. [Mod. L. reagens]
amino acid r. a r. used in the identification and quantification of amino acids.
Benedict-Hopkins-Cole r. magnesium glyoxalate, made from a mixture of oxalic acid and magnesium, used for testing proteins for the presence of tryptophan.
biuret r. an alkaline solution of copper sulfate.
Cleland's r. dithiothreitol
diazo r. two solutions, one of sodium nitrite, the other of acidified sulfanilic acid, used in bringing about diazotization.Ehrlich's diazo r;
Dische r. See Dische reaction.
Dische-Schwarz r. r. used in the colorimetric detection of RNA.
Drabkin's r. a solution used in the cyanmethemoglobin method of measuring hemoglobin. It consists of sodium bicarbonate, potassium cyanide, and potassium ferricyanide.
Dragendorff r. a r. used in the detection of alkaloids.
Edlefsen's r. an alkaline permanganate solution used in the determination of sugar in the urine.
Edman's r. phenylisothiocyanate
Ehrlich's diazo r. diazo r
Erdmann's r. a mixture of sulfuric and nitric acids, used in testing alkaloids.
Esbach's r. picric acid, citric acid, and water (in the proportions 1, 2, and 97) used for the detection of albumin in the urine.
Exton r. 50 g sulfosalicylic acid and 200g Na2SO4. 10H2O in a liter of water, used as a test for albumin.
Fehling's r. Fehling's solution
Folin's r. Folin's reaction
Fouchet's r. a 25% solution of trichloroacetic acid, containing 0.9% ferric chloride; a drop of the r. added at the surface line of barium chloride-impregnated filter paper which has been dipped in urine for 10 sec will give a green color if bilirubin is present. See also Fouchet's stain.
Froehde's r. sodium molybdate 1, in strong sulfuric acid 1000; gives various color reactions with alkaloids.
Frohn's r. 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.
Girard's r. the hydrazine of betaine chloride, used to extract ketonic steroids by forming water-soluble hydrazones with them.
Günzberg's r. phloroglucin and vanillin used as a r. in Günzberg's test.
Hahn's oxine r. an alcoholic solution of 8-hydroxyquinoline used in the determination of zinc, aluminum, magnesium, etc.
Hammarsten's r. a mixture of 1 part 25% solution of nitric acid and 19 parts 25% solution of hydrochloric acid; the addition of a few drops to a mixture of 1 part of this r. and 4 parts alcohol will give a green color if bile is present.
Ilosvay r. sulfanilic acid 0.5, dissolved in dilute acetic acid 150, mixed with naphthylamine 1, and dissolved in boiling water 20; the blue sediment which forms is dissolved in dilute acetic acid 150; a few drops of this r. added to water, saliva, or other fluid to be tested will produce a red color if nitrites are present.
Kasten's fluorescent Schiff r.'s fluorescent analogues of Schiff's r. which are fluorescent basic dyes lacking acidic side groups and containing one or more primary amine groups; used in cytochemical detection of DNA in Kasten's fluorescent Feulgen stain, polysaccharides in Kasten's fluorescent PAS stain, and proteins in the ninhydrin-Schiff stain; such analogues include acriflavine, auramine O, and flavophosphine N.
Lloyd's r. precipitated aluminum silicate, used in the determination of alkaloids.
Mandelin's r. a solution of ammonium vanadate in sulfuric acid, used in color tests for alkaloids.
Marme's r. a solution of potassium iodide and cadmium iodide used in testing for alkaloids.
Marquis' r. a solution of formaldehyde in sulfuric acid used in color tests for formaldehyde.
Mecke's r. a solution of selenous acid in sulfuric acid, used for color tests of alkaloids.
Meyer's r. a solution of phenolphthalein 0.032, in decinormal sodium hydroxide 21, with water (distilled from glass) sufficient to make 100; in the presence of minute traces of blood, the solution becomes purple or blue-red.
Millon's r. mercuric nitrate and nitric acid as used in the Millon reaction.
Nessler's r. a solution of potassium hydroxide, mercuric iodide, and potassium iodide; it yields a yellow color with ammonia (a brown precipitate with larger amounts) that can be used for quantitative assay.
Rosenthaler-Turk r. a solution of potassium arsenate in sulfuric acid used in obtaining color tests for various opium alkaloids.
Sanger's r. fluoro-2,4-dinitrobenzene
Schaer's r. an alcoholic or aqueous solution of chloral hydrate used as an extraction medium in investigations of alkaloids.
Scheibler's r. a solution of sodium tungstate in phosphoric acid used in tests for alkaloids.
Schiff's r. an aqueous solution of basic fuchsin or pararosaniline which is decolorized by sulfur dioxide, commonly prepared by addition of hydrochloric acid to a dye solution containing a metabisulphite or bisulphite salt; used for aldehydes and in histochemistry to detect polysaccharides, DNA, and proteins. See Feulgen stain, periodic acid-Schiff stain, ninhydrin-Schiff stain for proteins.
Scott-Wilson r. an alkaline solution of mercuric cyanide and silver nitrate used in the detection of acetone.
sulfhydryl r. r. that react with thiol groups, particularly those in proteins.
Sulkowitch's r. a r. for the detection of calcium in the urine, consisting of 2.5 g of oxalic acid, 2.5 g of ammonium oxalate, 5 cc of glacial acetic acid, and distilled water to make 150 cc; a milky precipitate of calcium oxalate is formed when the r. is added to urine that contains calcium.
Uffelmann's r. to a 2% solution of phenol in water is added to aqueous ferric chloride until the solution becomes violet in color; this turns lemon yellow in the presence of lactic acid, assumes an opaline tint in butyric acid, and is decolorized by hydrochloric acid.
Wurster's r. filter paper impregnated with tetramethyl-p-phenylenediamine, which turns blue in the presence of ozone or hydrogen peroxide.


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