Rayon —Use Purified Rayon(General Monograph).
Add the following:
Red-Cell Lysing Agent—
The reagent is available as a solution containing 0.33%potassium cyanide and 0.11%sodium nitroprusside and a quarternary ammonium salt as the surface active agent (5.5%).
[NOTE—The reagent is manufactured by Coulter Electronics Diagnostics,Hialeah,FLand is available from many suppliers under the name of Zapoglobin®(or Zap-oglobin®).]USP28
USP28
Red Phosphorus —See Phosphorus,Red.
Resazurin (Sodium), C12H6NNaO4—251.17—Abrownish-purple,crystalline powder.One g dissolves in 100mLof water,forming a deep violet-colored solution.
Hydrogen sulfide and other compounds containing the thiol group decolorize solutions of resazurin sodium,forming dihydroresorufin.When the decolorized solution is shaken in the presence of air,a rose color develops as a result of the formation of resorufin.
Retinyl Palmitate, C36H60O2—524.9—Yellow liquid.
Assay—
Mobile phase—
Prepare a mixture of acetonitrile and tetrahydrofuran (55:15).
Procedure—
Inject about 10µLinto a suitable liquid chromatograph (see Chromatography á621ñ)equipped with a 320-nm detector and a 4.6-mm ×15-cm column that contains packing L1.The flow rate is about 1mLper minute.The area of the C36H60O2peak is not less than 93%of the total peak area.
Rhodamine B (Tetraethylrhodamine), C28H31ClN2O3—479.01—Green crystals or a reddish-violet powder.Very soluble in water,yielding a bluish-red solution that is strongly fluorescent when dilute.Very soluble in alcohol;slightly soluble in dilute acids and in alkali solutions.In strong acid solution,it forms a pink complex with antimony that is soluble in isopropyl ether.
Clarity of solution—
Its solution (1in 200)is complete and clear.
Residue on ignition(Reagent test)—
Ignite 1g with 1mLof sulfuric acid:the residue weighs not more than 2mg (0.2%).
Rose Bengal Sodium (Disodium Salt of 4,5,6,7-Tetrachloro-2¢,4¢,5¢,7¢-tetraiodofluorescein), C20H2Cl4I4Na2O5—1017.64—Fine,rose-colored crystals or crystalline powder.Is practically odorless.Soluble in water.
NOTE—Render commercially available material suitably pure by the following treatment.Dissolve 8g in 200mLof water,and adjust to a pHbetween 10and 11,using short-range pHindicator paper.Add 200mLof acetone,while stirring gently,then add dilute hydrochloric acid (1in 10),while continuing to stir,until the pHof the solution reaches 4.0.Add 400mLmore of water,with stirring,and continue the stirring for 5minutes.Filter the crystals on a filtering funnel,and return the crystals to the beaker used for crystallization.Recrystallize three more times in the same manner,and dry the crystals at 110
for 12hours.Store in an amber bottle in a refrigerator at a temperature between 2and 8.Prepare this reagent fresh monthly.
for 12hours.Store in an amber bottle in a refrigerator at a temperature between 2and 8.Prepare this reagent fresh monthly.
Chromatographic purity—
Dissolve 100mg of rose bengal sodium,prepared as described above,in 100mLof water,and apply 10µLof the solution on suitable chromatographic paper.Develop the chromatogram by ascending chromatography,using a mixture of 1part of dilute alcohol (1in 4)and 1part of dilute stronger ammonia water (1in 12).Examine the chromatogram in daylight and under UVlight (360nm):no colored or fluorescent spot is visible other than the rose bengal sodium spot.
[NOTE—Asuitable grade is available commercially as “Silica Gel H”.]
Ruthenium Red (Ruthenium Oxychloride,Ammoniated), Ru2(OH)2Cl4·7NH3·3H2O—551.23—Abrownish-red to dark purple powder.Soluble in water.