Acetaldehyde TS —Mix 4mLof acetaldehyde,3mLof alcohol,and 1mLof water.Prepare this solution fresh.

Acetate Buffer TS —Dissolve 320g of ammonium acetate in 500mLof water,add 5mLof glacial acetic acid,dilute with water to 1000.0mL,and mix.This solution has a pHbetween 5.9and 6.0.

Acetic Acid,Glacial,TS —Determine the water content of a specimen of glacial acetic acid by the Titrimetric Method(see Water Determination á921ñ).If the acid contains more than 0.05%of water,add a few mLof acetic anhydride,mix,allow to stand overnight,and again determine the water content.If the acid contains less than 0.02%of water,add sufficient water to make the final concentration between 0.02%and 0.05%,mix,allow to stand overnight,and again determine the water content.Repeat the adjustment with acetic anhydride or water,as necessary,until the resulting solution shows a water content between 0.02%and 0.05%.

Acetic Acid–Ammonium Acetate Buffer TS —Dissolve 77.1g of ammonium acetate in water,add 57mLof glacial acetic acid,and dilute with water to 1000mL.

Acetone,Buffered,TS —Dissolve 8.15g of sodium acetate and 42g of sodium chloride in about 100mLof water,and add 68mLof 0.1Nhydrochloric acid and 150mLof acetone.Mix,and dilute with water to 500mL.

Acid Ferric Chloride TS —Mix 60mLof glacial acetic acid with 5mLof sulfuric acid,add 1mLof ferric chloride TS,mix,and cool.

Acid Ferrous Sulfate TS —See Ferrous Sulfate,Acid,TS.

Acid Stannous Chloride TS —See Stannous Chloride,Acid,TS.

Acid Stannous Chloride TS,Stronger —See Stannous Chloride,Acid,Stronger,TS.

Albumen TS —Carefully separate the white from the yolk of a strictly fresh hen's egg.Shake the white with 100mLof water until mixed and all but the chalaza has undergone solution;then filter.Prepare the solution fresh.

Alcohol–Phenol TS —Dissolve 780mg of phenol in alcohol to make 100mL.

Alcoholic Ammonia TS —See Ammonia TS,Alcoholic.

Alcoholic Mercuric Bromide TS —See Mercuric Bromide TS,Alcoholic.

Alcoholic Potassium Hydroxide TS —See Potassium Hydroxide TS,Alcoholic.

Alkaline Cupric Citrate TS —See Cupric Citrate TS,Alkaline.

Alkaline Cupric Iodide TS —See Cupric Iodide TS,Alkaline.

Alkaline Cupric Tartrate TS (Fehling's Solution)—See Cupric Tartrate TS,Alkaline.

Alkaline Mercuric–Potassium Iodide TS —See Mercuric–Potassium Iodide TS,Alkaline.

Alkaline Picrate TS —See Picrate TS,Alkaline.

Alkaline Sodium Hydrosulfite TS —See Sodium Hydrosulfite TS,Alkaline.

Amaranth TS —Dissolve 20mg of amaranth in 10mLof water.

Aminonaphtholsulfonic Acid TS —Accurately weigh 5g of sodium sulfite,94.3g of sodium bisulfite,and 700mg of 1,2,4-aminonaphtholsulfonic acid,and mix.Prepare aminonaphtholsulfonic acid TSfresh on the day of use by dissolving 1.5g of the dry mixture in 10mLof water.

Ammonia–Ammonium Chloride Buffer TS —Dissolve 67.5g of ammonium chloride in water,add 570mLof ammonium hydroxide,and dilute with water to 1000mL.

Ammonia–Cyanide TS —Dissolve 2g of potassium cyanide in 15mLof ammonium hydroxide,and dilute with water to 100mL.

Ammonia TS —It contains between 9.5%and 10.5%of NH3.Prepare by diluting 400mLof Ammonia Water,Stronger(see in the section Reagents)with water to make 1000mL.

Ammonia TS,Alcoholic —Asolution of ammonia gas in alcohol.Clear,colorless liquid having a strong odor of ammonia.Specific gravity:about 0.80.It contains between 9%and 11%of NH3.Store it in alkali-resistant containers,in a cold place.

Ammonia TS,Stronger —Use Ammonia Water,Stronger(see in the section Reagents).

Ammoniacal Potassium Ferricyanide TS —Dissolve 2g of potassium ferricyanide in 75mLof water,add 25mLof ammonium hydroxide,and mix.

Ammoniated Cupric Oxide TS —See Cupric Oxide,Ammoniated,TS.

Ammonium Acetate TS —Dissolve 10g of ammonium acetate in water to make 100mL.

Ammonium Carbonate TS —Dissolve 20g of ammonium carbonate and 20mLof ammonia TSin water to make 100mL.

Ammonium Chloride TS —Dissolve 10.5g of ammonium chloride in water to make 100mL.

Ammonium Chloride–Ammonium Hydroxide TS —Mix equal volumes of water and ammonium hydroxide,and saturate with ammonium chloride.

Ammonium Molybdate TS —Dissolve 6.5g of finely powdered molybdic acid in a mixture of 14mLof water and 14.5mLof ammonium hydroxide.Cool the solution,and add it slowly,with stirring,to a well-cooled mixture of 32mLof nitric acid and 40mLof water.Allow to stand for 48hours,and filter through a fine-porosity,sintered-glass crucible.This solution deteriorates upon standing and is unsuitable for use if,upon the addition of 2mLof dibasic sodium phosphate TSto 5mLof the solution,an abundant yellow precipitate does not form at once or after slight warming.Store it in the dark.If a precipitate forms during storage,use only the clear supernatant.

Ammonium Oxalate TS —Dissolve 3.5g of ammonium oxalate in water to make 100mL.

Ammonium Phosphate,Dibasic,TS(Ammonium Phosphate TS)— Dissolve 13g of dibasic ammonium phosphate in water to make 100mL.

Ammonium Polysulfide TS —Yellow liquid,made by saturating ammonium sulfide TSwith sulfur.

Ammonium Reineckate TS —Shake about 500mg of ammonium reineckate with 20mLof water frequently during 1hour,and filter.Use within 2days.

Ammonium Sulfide TS —Saturate ammonia TSwith hydrogen sulfide by bubbling hydrogen sulfide gas through the solution for 1minute.This solution must be freshly prepared.The solution is not rendered turbid either by magnesium sulfate TSor by calcium chloride TS(carbonate).This solution is unstable for use if an abundant precipitate of sulfur is present.

Ammonium Thiocyanate TS —Dissolve 8g of ammonium thiocyanate in water to make 100mL.

Ammonium Vanadate TS —Dissolve 2.5g of ammonium vanadate in 500mLof boiling water,cool,and add 20mLof nitric acid.Mix,cool,and add water to make 1L.Store in polyethylene containers.

Anthrone TS —Within 12hours of use,rapidly dissolve 35mg of anthrone in a hot mixture of 35mLof water and 65mLof sulfuric acid.Immediately cool in an ice bath to room temperature,and filter through glass wool.Allow the solution to stand at room temperature for 30minutes before use.

Antimony Trichloride TS —Dissolve 20g of antimony trichloride in chloroform to make 100mL.Filter if necessary.

Barium Chloride TS —Dissolve 12g of barium chloride in water to make 100mL.

Barium Hydroxide TS —Asaturated solution of barium hydroxide in recently boiled water.Prepare the solution fresh.

Barium Nitrate TS —Dissolve 6.5g of barium nitrate in water to make 100mL.

Betanaphthol TS —See 2-Naphthol TS.

Biuret Reagent TS —Dissolve 1.5g of cupric sulfate and 6.0g of potassium sodium tartrate in 500mLof water in a 1000-mLvolumetric flask.Add 300mLof carbonate-free sodium hydroxide solution (1in 10),dilute with carbonate-free sodium hydroxide solution (1in 10)to 1000mL,and mix.

Blue Tetrazolium TS —Dissolve 500mg of blue tetrazolium in alcohol to make 100mL.

Brilliant Blue G TS —Transfer 25mg of brilliant blue Gto a 100-mLvolumetric flask,add 12.5mLof alcohol and 25mLof phosphoric acid,dilute with water to volume,and mix.

Bromine TS(Bromine Water)— Asaturated solution of bromine,prepared by agitating 2to 3mLof bromine with 100mLof cold water in a glass-stoppered bottle,the stopper of which should be lubricated with petrolatum.Store it in a cold place,protected from light.

Bromine–Sodium Acetate TS —Dissolve 100g of sodium acetate in 1000mLof glacial acetic acid,add 50mLof bromine,and mix.

p-Bromoaniline TS —Add 8g of p-bromoaniline to a mixture of 380mLof thiourea-saturated glacial acetic acid,10mLof sodium chloride solution (1in 5),5mLof oxalic acid solution (1in 20),and 5mLof dibasic sodium phosphate solution (1in 10)in a low-actinic glass bottle.Mix,and allow to stand overnight before using.Protect from light,and use within 7days.

Bromocresol Blue TS —Use Bromocresol Green TS.

Bromocresol Green TS —Dissolve 50mg of bromocresol green in 100mLof alcohol,and filter if necessary.

Bromocresol Green–Methyl Red TS —Dissolve 0.15g of bromocresol green and 0.1g of methyl red in 180mLof alcohol,and dilute with water to 200mL.

Bromocresol Purple TS —Dissolve 250mg of bromocresol purple in 20mLof 0.05Nsodium hydroxide,and dilute with water to 250mL.

Bromophenol Blue TS —Dissolve 100mg of bromophenol blue in 100mLof diluted alcohol,and filter if necessary.

Bromothymol Blue TS —Dissolve 100mg of bromothymol blue in 100mLof diluted alcohol,and filter if necessary.

Buffered Acetone TS —See Acetone,Buffered,TS.

Calcium Chloride TS —Dissolve 7.5g of calcium chloride in water to make 100mL.

Calcium Hydroxide TS —Use Calcium Hydroxide Topical Solution(USPmonograph).

Calcium Sulfate TS —Asaturated solution of calcium sulfate in water.

Ceric Ammonium Nitrate TS —Dissolve 6.25g of ceric ammonium nitrate in 10mLof 0.25Nnitric acid.Use within 3days.

Chloral Hydrate TS —Dissolve 50g of chloral hydrate in a mixture of 15mLof water and 10mLof glycerin.

Chlorine TS(Chlorine Water)— Asaturated solution of chlorine in water.Place the solution in small,completely filled,light-resistant containers.Chlorine TS,even when kept from light and air,is apt to deteriorate.Store it in a cold,dark place.For full strength,prepare this solution fresh.

Chromotropic Acid TS —Dissolve 50mg of chromotropic acid or its disodium salt in 100mLof 75percent sulfuric acid,which may be made by cautiously adding 75mLof sulfuric acid to 33.3mLof water.

Cobalt–Uranyl Acetate TS —Dissolve,with warming,40g of uranyl acetate in a mixture of 30g of glacial acetic acid and sufficient water to make 500mL.Similarly,prepare a solution containing 200g of cobaltous acetate in a mixture of 30g of glacial acetic acid and sufficient water to make 500mL.Mix the two solutions while still warm,and cool to 20.Maintain the temperature at 20for about 2hours to separate the excess salts from solution,and then pass through a dry filter.

Cobaltous Chloride TS —Dissolve 2g of cobaltous chloride in 1mLof hydrochloric acid and sufficient water to make 100mL.

Congo Red TS —Dissolve 500mg of congo red in a mixture of 10mLof alcohol and 90mLof water.

m-Cresol Purple TS —Dissolve 0.10g of metacresol purple in 13mLof 0.01Nsodium hydroxide,dilute with water to 100mL,and mix.

Cresol Red TS —Triturate 100mg of cresol red in a mortar with 26.2mLof 0.01Nsodium hydroxide until solution is complete,then dilute the solution with water to 250mL.

Cresol Red–Thymol Blue TS —Add 15mLof thymol blue TSto 5mLof cresol red TS,and mix.

Crystal Violet TS —Dissolve 100mg of crystal violet in 10mLof glacial acetic acid.

Cupric Acetate TS —Dissolve 100mg of cupric acetate in about 5mLof water to which a few drops of acetic acid have been added.Dilute to 100mL,and filter,if necessary.

Cupric Acetate TS,Stronger (Barfoed's Reagent)— Dissolve 13.3g of cupric acetate in a mixture of 195mLof water and 5mLof acetic acid.

Cupric-Ammonium Sulfate TS —To cupric sulfate TSadd ammonia TS,dropwise,until the precipitate initially formed is nearly but not completely dissolved.Allow to settle,and decant the clear solution.Prepare this solution fresh.

Cupric Citrate TS —Dissolve 25g of cupric sulfate,50g of citric acid,and 144g of anhydrous sodium carbonate in water,and dilute with water to 1000mL.

Cupric Citrate TS,Alkaline —With the aid of heat,dissolve 173g of dihydrated sodium citrate and 117g of monohydrated sodium carbonate in about 700mLof water,and filter through paper,if necessary,to obtain a clear solution.In a separate container dissolve 17.3g of cupric sulfate in about 100mLof water,and slowly add this solution,with constant stirring,to the first solution.Cool the mixture,add water to make 1000mL,and mix.

Cupric Iodide TS,Alkaline —Dissolve 7.5g of cupric sulfate (CuSO4·5H2O)in about 100mLof water.In a separate container dissolve 25g of anhydrous sodium carbonate,20g of sodium bicarbonate,and 25g of potassium sodium tartrate in about 600mLof water.With constant stirring,add the cupric sulfate solution to the bottom of the alkaline tartrate solution by means of a funnel that touches the bottom of the container.Add 1.5g of potassium iodide,200g of anhydrous sodium sulfate,50to 150mLof 0.02Mpotassium iodate,and sufficient water to make 1000mL.

Cupric Oxide,Ammoniated,TS (Schweitzer's Reagent)—Dissolve 10g of cupric sulfate in 100mLof water,add sufficient sodium hydroxide solution (1in 5)to precipitate the copper hydroxide,collect the latter on a filter,and wash free from sulfate with cold water.Dissolve the precipitate,which must be kept wet during the entire process,in the minimum quantity of ammonia TSnecessary for complete solution.

Cupric Sulfate TS —Dissolve 12.5g of cupric sulfate in water to make 100mL.

Cupric Tartrate TS,Alkaline(Fehling's Solution)— The Copper Solution (A)—Dissolve 34.66g of carefully selected,small crystals of cupric sulfate,showing no trace of efflorescence of adhering moisture,in water to make 500mL.Store this solution in small,tight containers.

Delafield's Hematoxylin TS —Prepare 400mLof a saturated solution of ammonium alum (Solution A).Dissolve 4g of hematoxylin in 25mLof alcohol,mix it with Solution A,and allow it to stand for 4days in a flask closed with a pledget of purified cotton and exposed to light and air (Solution B).Then filter Solution B,and add to it a Solution Cconsisting of a mixture of 100mLof glycerin and 100mLof methanol.Mix,and allow the mixture to stand in a warm place,exposed to light,for 6weeks until it becomes dark-colored.Store in tightly stoppered bottles.

Denigès'Reagent —See Mercuric Sulfate TS.

Diazobenzenesulfonic Acid TS —Place in a beaker 1.57g of sulfanilic acid,previously dried at 105for 3hours,add 80mLof water and 10mLof diluted hydrochloric acid,and warm on a steam bath until dissolved.Cool to 15(some of the sulfanilic acid may separate but will dissolve later),and add slowly,with constant stirring,6.5mLof sodium nitrite solution (1in 10).Then dilute with water to 100mL.

Dichlorofluorescein TS —Dissolve 100mg of dichlorofluorescein in 60mLof alcohol,add 2.5mLof 0.1Nsodium hydroxide,mix,and dilute with water to 100mL.

Dicyclohexylamine Acetate TS —Dissolve 50g of dicyclohexylamine in 150mLof acetone,cool in an ice bath,and add,with stirring,a solution consisting of 18mLof glacial acetic acid in 150mLof acetone.Recrystallize the precipitate that forms,by heating the mixture to boiling and allowing it to cool in an ice bath,then collect the crystals on a filtering funnel,wash with a small volume of acetone,and air-dry.Dissolve 300mg of the dicyclohexylamine acetate so obtained in 200mLof a mixture of 6volumes of chloroform and 4volumes of water-saturated ether.Use immediately.

2,7-Dihydroxynaphthalene TS —Dissolve 100mg of 2,7-dihydroxynaphthalene in 1000mLof sulfuric acid,and allow the solution to stand until the yellow color disappears.If the solution is very dark,discard it and prepare a new solution from a different supply of sulfuric acid.This solution is stable for approximately 1month if stored in a dark bottle.

Diiodofluorescein TS —Dissolve 500mg of diiodofluorescein in a mixture of 75mLof alcohol and 30mLof water.

Diluted Lead Subacetate TS —See Lead Subacetate TS,Diluted.

p-Dimethylaminobenzaldehyde TS —Dissolve 125mg of p-dimethylaminobenzaldehyde in a cooled mixture of 65mLof sulfuric acid and 35mLof water,and add 0.05mLof ferric chloride TS.Use within 7days.

Dinitrophenylhydrazine TS —Carefully mix 10mLof water and 10mLof sulfuric acid,and cool.To the mixture,contained in a glass-stoppered flask,add 2g of 2,4-dinitrophenylhydrazine,and shake until dissolved.To the solution add 35mLof water,mix,cool,and filter.

Diphenylamine TS —Dissolve 1.0g of diphenylamine in 100mLof sulfuric acid.The solution should be colorless.

Diphenylcarbazone TS —Dissolve 1g of crystalline diphenylcarbazone in 75mLof alcohol,then add alcohol to make 100mL.Store in a brown bottle.

Dithizone TS —Dissolve 25.6mg of dithizone in 100mLof alcohol.Store in a cold place,and use within 2months.

Dragendorff's TS —Mix 850mg of bismuth subnitrate with 40mLof water and 10mLof glacial acetic acid (Solution A).Dissolve 8g of potassium iodide in 20mLof water (Solution B).Mix equal portions of Solution Aand Solution Bto obtain a stock solution,which can be stored for several months in a dark bottle.Mix 10mLof the stock solution with 20mLof glacial acetic acid,and dilute with water to make 100mL.

Edetate Disodium TS —Dissolve 1g of edetate disodium in 950mLof water,add 50mLof alcohol,and mix.

Eosin Y TS (adsorption indicator)—Dissolve 50mg of eosin Yin 10mLof water.

Eriochrome Black TS —Dissolve 200mg of eriochrome black Tand 2g of hydroxylamine hydrochloride in methanol to make 50mL.

Eriochrome Cyanine TS —Dissolve 750mg of eriochrome cyanine Rin 200mLof water,add 25g of sodium chloride,25g of ammonium nitrate,and 2mLof nitric acid,and dilute with water to 1000mL.

Fehling's Solution —See Cupric Tartrate TS,Alkaline.

Ferric Ammonium Sulfate TS —Dissolve 8g of ferric ammonium sulfate in water to make 100mL.

Ferric Chloride TS —Dissolve 9g of ferric chloride in water to make 100mL.

Ferroin TS —Dissolve 0.7g of ferrous sulfate and 1.76g of o-phenanthroline monohydrochloride monohydrate in water,and dilute with water to 100mL.

Ferrous Sulfate TS —Dissolve 8g of clear crystals of ferrous sulfate in about 100mLof recently boiled and thoroughly cooled water.Prepare this solution fresh.

Ferrous Sulfate,Acid,TS —Dissolve 7g of ferrous sulfate crystals in 90mLof recently boiled and thoroughly cooled water,and add sulfuric acid to make 100mL.Prepare this solution immediately prior to use.

Folin-Ciocalteu Phenol TS —Into a 1500-mLflask introduce 100g of sodium tungstate,25g of sodium molybdate,700mLof water,50mLof phosphoric acid,and 100mLof hydrochloric acid.Gently reflux the mixture for about 10hours,and add 150g of lithium sulfate,50mLof water,and a few drops of bromine.Boil the mixture,without the condenser,for about 15minutes,or until the excess bromine is expelled.Cool,dilute with water to 1L,and filter:the filtrate has no greenish tint.Before use,dilute 1part of the filtrate with 1part of water.When used for protein determination (i.e.,Lowry assay),this reagent must be further diluted (1:5)with water.See Method 2in Total Protein Assay under Biotechnology-Derived Articles—Tests á1047ñ.

Formaldehyde TS —Use Formaldehyde Solution(see in the section Reagents).

Fuchsin–Pyrogallol TS —Dissolve 100mg of basic fuchsin in 50mLof water that previously has been boiled for 15minutes and allowed to cool slightly.Cool,add 2mLof a saturated solution of sodium bisulfite,mix,and allow to stand for not less than 3hours.Add 0.9mLof hydrochloric acid,mix,and allow to stand overnight.Add 100mg of pyrogallol,shake until solution is effected,and dilute with water to 100mL.Store in an amber-colored glass bottle in a refrigerator.

Fuchsin–Sulfurous Acid TS —Dissolve 200mg of basic fuchsin in 120mLof hot water,and allow the solution to cool.Add a solution of 2g of anhydrous sodium sulfite in 20mLof water,then add 2mLof hydrochloric acid.Dilute the solution with water to 200mL,and allow to stand for at least 1hour.Prepare this solution fresh.

Gastric Fluid,Simulated,TS —Dissolve 2.0g of sodium chloride and 3.2g of purified pepsin,that is derived from porcine stomach mucosa,with an activity of 800to 2500units per mg of protein,in 7.0mLof hydrochloric acid and sufficient water to make 1000mL.[NOTE—Pepsin activity is described in the Food Chemicals Codex specifications under General Tests and Assays.]This test solution has a pHof about 1.2.

Gelatin TS (for the assay of Corticotropin Injection)—Dissolve 340g of acid-treated precursor gelatin (Type A)in water to make 1000mL.Heat the solution in an autoclave at 115for 30minutes after the exhaust line temperature has reached 115.Cool the solution,and add 10g of phenol and 1000mLof water.Store in tight containers in a refrigerator.

Glacial Acetic Acid TS —See Acetic Acid,Glacial,TS.

Glucose Oxidase–Chromogen TS —Asolution containing,in each mL,0.5µmol of 4-aminoantipyrine,22.0µmol of sodium p-hydroxybenzoate,not less than 7.0units of glucose oxidase,and not less than 0.5units of peroxidase,and buffered to a pHof 7.0±0.1.

Glycerin Base TS —To 200g of glycerin add water to bring the total weight to 235g.Add 140mLof 1Nsodium hydroxide and 50mLof water.

Gold Chloride TS —Dissolve 1g of gold chloride in 35mLof water.

Hydrogen Peroxide TS —Use Hydrogen Peroxide Topical Solution(USPmonograph).

Hydrogen Sulfide TS —Asaturated solution of hydrogen sulfide,made by passing H2Sinto cold water.Store it in small,dark amber-colored bottles,filled nearly to the top.It is unsuitable unless it possesses a strong odor of H2S,and unless it produces at once a copious precipitate of sulfur when added to an equal volume of ferric chloride TS.Store in a cold,dark place.

Change to read:

Hydroxylamine Hydrochloride TS —Dissolve 3.5g of hydroxylamine hydrochloride in 95mLof 60percent alcohol,and add 0.5mLof bromophenol blue solution (1in 1000of alcohol)USP28and 0.5Nalcoholic potassium hydroxide until a greenish tint develops in the solution.Then add 60percent alcohol to make 100mL.

8-Hydroxyquinoline TS —Dissolve 5g of 8-hydroxyquinoline in alcohol to make 100mL.

Indigo Carmine TS(Sodium Indigotindisulfonate TS)— Dissolve a quantity of sodium indigotindisulfonate,equivalent to 180mg of C16H8N2O2(SO3Na)2,in water to make 100mL.Use within 60days.

Indophenol–Acetate TS (for the assay of Corticotropin Injection)—To 60mLof standard dichlorophenol-indophenol solution (see in the section Volumetric Solutions)add water to make 250mL.Add to the resulting solution an equal volume of sodium acetate solution freshly prepared by dissolving 13.66g of anhydrous sodium acetate in water to make 500mLand adjusting with 0.5Nacetic acid to a pHof 7.Store in a refrigerator,and use within 2weeks.

Intestinal Fluid,Simulated,TS —Dissolve 6.8g of monobasic potassium phosphate in 250mLof water,mix,and add 77mLof 0.2Nsodium hydroxide and 500mLof water.Add 10.0g of pancreatin,mix,and adjust the resulting solution with either 0.2Nsodium hydroxide or 0.2Nhydrochloric acid to a pHof 6.8±0.1.Dilute with water to 1000mL.

Iodine TS —Use 0.1N Iodine(see in the section Volumetric Solutions).

Iodine,Diluted TS— Transfer 10.0mLof 0.1Niodine VSto a 100-mLvolumetric flask,dilute with water to volume,and mix.

Iodine Monochloride TS —Dissolve 10g of potassium iodide and 6.44g of potassium iodate in 75mLof water in a glass-stoppered container.Add 75mLof hydrochloric acid and 5mLof chloroform,and adjust to a faint iodine color (in the chloroform)by adding dilute potassium iodide or potassium iodate solution.If much iodine is liberated,use a stronger solution of potassium iodate than 0.01Mat first,making the final adjustment with the 0.01Mpotassium iodate.Store in a dark place,and readjust to a faint iodine color as necessary.

Iodine and Potassium Iodide TS —Dissolve 500mg of iodine and 1.5g of potassium iodide in 25mLof water.

Iodobromide TS —Dissolve 20g of iodine monobromide in glacial acetic acid to make 1000mL.Store in glass containers,protected from light.

Iodochloride TS —Dissolve 16.5g of iodine monochloride in 1000mLof glacial acetic acid.

Iodoplatinate TS —Dissolve 300mg of platinic chloride in 97mLof water.Immediately prior to use,add 3.5mLof potassium iodide TS,and mix.

Iron–Phenol TS(Iron-Kober Reagent)— Dissolve 1.054g of ferrous ammonium sulfate in 20mLof water,and add 1mLof sulfuric acid and 1mLof 30percent hydrogen peroxide.Mix,heat until effervescence ceases,and dilute with water to 50mL.To 3volumes of this solution contained in a volumetric flask add sulfuric acid,with cooling,to make 100volumes.Purify phenol by distillation,discarding the first 10%and the last 5%,collecting the distillate,with exclusion of moisture,in a dry,tared glass-stoppered flask of about twice the volume of the phenol.Solidify the phenol in an ice bath,breaking the top crust with a glass rod to ensure complete crystallization.Weigh the flask and its contents,add to the phenol 1.13times its weight of the iron–sulfuric acid solution prepared as directed,insert the stopper in the flask,and allow to stand,without cooling but with occasional mixing,until the phenol is liquefied.Shake the mixture vigorously until mixed,allow to stand in the dark for 16to 24hours,and again weigh the flask and its contents.To the mixture add 23.5%of its weight of a solution of 100volumes of sulfuric acid in 110volumes of water,mix,transfer to dry glass-stoppered bottles,and store in the dark,protected from atmospheric moisture.Use within 6months.Dispense the reagent from a small-bore buret,arranged to exclude moisture,capable of delivering 1mLin 30seconds or less,and having no lubricant,other than reagent,on its stopcock.Wipe the buret tip with tissue before each addition.

Iron Salicylate TS —Dissolve 500mg of ferric ammonium sulfate in 250mLof water containing 10mLof diluted sulfuric acid,and add water to make 500mL.To 100mLof the resulting solution add 50mLof a 1.15%solution of sodium salicylate,20mLof diluted acetic acid,and 80mLof a 13.6%solution of sodium acetate,then add water to make 500mL.Store in a well-closed container.Protect from light.Use within 2weeks.

Lead Acetate TS —Dissolve 9.5g of clear,transparent crystals of lead acetate in recently boiled water to make 100mL.Store in well-stoppered bottles.

Lead Acetate TS,Alcoholic —Dissolve 2g of clear,transparent crystals of lead acetate in alcohol to make 100mL.Store in tight containers.

Lead Subacetate TS —Triturate 14g of lead monoxide to a smooth paste with 10mLof water,and transfer the mixture to a bottle,using an additional 10mLof water for rinsing.Dissolve 22g of lead acetate in 70mLof water,and add the solution to the lead oxide mixture.Shake it vigorously for 5minutes,then set it aside,shaking it frequently,during 7days.Finally filter,and add enough recently boiled water through the filter to make 100mL.

Lead Subacetate TS,Diluted —Dilute 3.25mLof lead subacetate TSwith water,recently boiled and cooled,to make 100mL.Store in small,well-filled,tight containers.

Litmus TS —Digest 25g of powdered litmus with three successive100-mLportions of boiling alcohol,continuing each extraction for about 1hour.Filter,wash with alcohol,and discard the alcohol filtrate.Macerate the residue with about 25mLof cold water for 4hours,filter,and discard the filtrate.Finally digest the residue with 125mLof boiling water for 1hour,cool,and filter.

Locke-Ringer's Solution —See Locke-Ringer's TS.

Locke-Ringer's TS(Locke-Ringer's Solution)—

Magnesia Mixture TS —Dissolve 5.5g of magnesium chloride and 7g of ammonium chloride in 65mLof water,add 35mLof ammonia TS,set the mixture aside for a few days in a well-stoppered bottle,and filter.If the solution is not perfectly clear,filter it before using.

Magnesium Sulfate TS —Dissolve 12g of crystals of magnesium sulfate,selected for freedom from efflorescence,in water to make 100mL.

Malachite Green TS —Dissolve 1g of malachite green oxalate in 100mLof glacial acetic acid.

Mallory's Stain —Dissolve 500mg of water-soluble aniline blue,2g of orange G,and 2g of oxalic acid in 100mLof water.

Mayer's Reagent —See Mercuric–Potassium Iodide TS.

Mercuric Acetate TS —Dissolve 6.0g of mercuric acetate in glacial acetic acid to make 100mL.Store in tight containers,protected from direct sunlight.

Mercuric–Ammonium Thiocyanate TS —Dissolve 30g of ammonium thiocyanate and 27g of mercuric chloride in water to make 1000mL.

Mercuric Bromide TS,Alcoholic —Dissolve 5g of mercuric bromide in 100mLof alcohol,employing gentle heat to facilitate solution.Store in glass containers,protected from light.

Mercuric Chloride TS —Dissolve 6.5g of mercuric chloride in water to make 100mL.

Mercuric Iodide TS(Valser's Reagent)— Slowly add potassium iodide solution (1in 10)to red mercuric iodide until almost all of the latter is dissolved,and filter off the excess.Asolution containing 10g of potassium iodide in 100mLdissolves approximately 14g of HgI2at 20.

Mercuric Nitrate TS —Dissolve 40g of mercuric oxide (red or yellow)in a mixture of 32mLof nitric acid and 15mLof water.Store in glass containers,protected from light.

Mercuric–Potassium Iodide TS(Mayer's Reagent)— Dissolve 1.358g of mercuric chloride in 60mLof water.Dissolve 5g of potassium iodide in 10mLof water.Mix the two solutions,and dilute with water to 100mL.

Mercuric–Potassium Iodide TS,Alkaline (Nessler's Reagent)— Dissolve 143g of sodium hydroxide in 700mLof water.Dissolve 50g of red mercuric iodide and 40g of potassium iodide in 200mLof water.Pour the iodide solution into the hydroxide solution,and dilute with water to 1000mL.Allow to settle,and use the clear supernatant.

Mercuric Sulfate TS(Denigès'Reagent)— Mix 5g of yellow mercuric oxide with 40mLof water,and while stirring slowly add 20mLof sulfuric acid,then add another 40mLof water,and stir until completely dissolved.

Mercurous Nitrate TS —Dissolve 15g of mercurous nitrate in a mixture of 90mLof water and 10mLof diluted nitric acid.Store in dark,amber-colored bottles in which a small globule of mercury has been placed.

Metaphenylenediamine Hydrochloride TS —Dissolve 1g of metaphenylenediamine hydrochloride in 200mLof water.The solution must be colorless when used.If necessary,decolorize by heating with activated charcoal.

Metaphosphoric–Acetic Acids TS —Dissolve 15g of metaphosphoric acid in 40mLof glacial acetic acid and sufficient water to make 500mL.Store in a cold place,and use within 2days.

3-Methyl-2-benzothiazolinone Hydrazone Hydrochloride TS —Dissolve 0.1g of 3-methyl-2-benzothiazolinone hydrazone hydrochloride monohydrate in 10mLof water,dilute the resulting solution with methanol to 100mL,and mix.

Methyl Orange TS —Dissolve 100mg of methyl orange in 100mLof water,and filter if necessary.

Methyl Purple TS —Use Methyl Red–Methylene Blue TS.

Methyl Red TS —Dissolve 100mg of methyl red in 100mLof alcohol,and filter if necessary.

Methyl Red TS,Methanolic —Dissolve 1g of methyl red in 100mLof methanol,and filter,if necessary.Store protected from light,and use within 21days.

Methyl Red–Methylene Blue TS —Add 10mLof methyl red TSto 10mLof methylene blue TS,and mix.

Methyl Violet TS —Use Crystal Violet TS.

Methyl Yellow TS— Prepare a solution containing 0.10mg per mLin alcohol.

Methyl Yellow–Methylene Blue TS —Dissolve 1g of methyl yellow and 100mg of methylene blue in 125mLof methanol.

Methylene Blue TS —Dissolve 125mg of methylene blue in 100mLof alcohol,and dilute with alcohol to 250mL.

Methylthionine Perchlorate TS —To 500mLof potassium perchlorate solution (1in 1000)add dropwise,with constant shaking,methylene blue solution (1in 100)until a slight,permanent turbidity results.Allow the precipitate to settle,decant the supernatant through paper,and use only the clear solution.

Millon's Reagent —To 2mLof mercury in a conical flask add 20mLof nitric acid.Shake the flask under a hood to break up the mercury into small globules.After about 10minutes,add 35mLof water,and,if a precipitate or crystals appear,add sufficient dilute nitric acid (1in 5,prepared from nitric acid from which the oxides have been removed by blowing air through it until it is colorless)to dissolve the separated solid.Add sodium hydroxide solution (1in 10)dropwise,with thorough mixing,until the curdy precipitate that forms after the addition of each drop no longer redissolves but is dispersed to form a suspension.Add 5mLmore of the dilute nitric acid,and mix.Prepare this solution fresh.

Molybdo-phosphotungstate TS(Folin-Denis Reagent)— To about 350mLof water contained in a round-bottom flask add 50g of sodium tungstate,12g of phosphomolybdic acid,and 25mLof phosphoric acid.Boil the mixture under a reflux condenser for 2hours,then cool,dilute with water to 500mL,and mix.Store in tight containers,protected from light,and in a cold place.

1-Naphthol Reagent —Dissolve 1g of 1-naphthol in 25mLof methanol.Prepare this solution fresh.

1-Naphthol TS —Use 1-Naphthol Reagent.

2-Naphthol TS(Betanaphthol TS)— Dissolve 1g of 2-naphthol in 100mLof sodium hydroxide solution (1in 100).

p-Naphtholbenzein TS —Dissolve 250mg of p-naphtholbenzein in 100mLof glacial acetic acid.

N-(1-Naphthyl)ethylenediamine Dihydrochloride TS —Dissolve 100mg of N-(1-naphthyl)ethylenediamine dihydrochloride in 100mLof a mixture of 7parts of acetone and 3parts of water.

Nessler's Reagent —See Mercuric–Potassium Iodide TS,Alkaline.

Neutral Red TS —Dissolve 100mg of neutral red in 100mLof 50%alcohol.

Nickel Standard Solution TS —Dissolve 4.78g of nickel(II)sulfate heptahydrate in water,and dilute with water to 1000mL.Immediately prior to use,dilute 10.0mLof the solution so obtained with water to 1000mL.Suitable nickel standard solutions are also available commercially.

Ninhydrin TS —Use Triketohydrindene Hydrate TS.

p-Nitroaniline TS —To 350mg of p-nitroaniline add 1.5mLof hydrochloric acid,and mix.Dilute with water to 50mL,mix,and allow to settle.Place 5mLof the clear supernatant in a 100-mLvolumetric flask,and immerse it in an ice bath.While it is in the ice bath,add 1mLof hydrochloric acid,then add,in small portions,2mLof sodium nitrite solution (1in 100),dilute with water to volume,and mix.

Nitrophenanthroline TS —Dissolve 150mg of 5-nitro-1,10-phenanthroline in 15mLof freshly prepared ferrous sulfate solution (1in 140).

Oracet Blue B TS —A1in 200solution of oracet blue Bin glacial acetic acid.

Orthophenanthroline TS —Dissolve 150mg of orthophenanthroline in 10mLof a solution of ferrous sulfate,prepared by dissolving 700mg of clear crystals of ferrous sulfate in 100mLof water.The ferrous sulfate solution must be prepared immediately before dissolving the orthophenanthroline.Store in well-closed containers.

Oxalic Acid TS —Dissolve 6.3g of oxalic acid in water to make 100mL.

Palladium Chloride TS,Buffered —Weigh 500mg of palladium chloride into a 250-mLbeaker,add 5mLof concentrated hydrochloric acid,and warm the mixture on a steam bath.Add 200mLof hot water in small increments with continued heating until solution is complete.Transfer the solution to a 250-mLvolumetric flask,and dilute with water to volume.Transfer 50mLto a 100-mLvolumetric flask.Add 10mLof 1Msodium acetate and 9.6mLof 1Nhydrochloric acid.Dilute with water to volume.

Perchloric Acid TS —Dilute 8.5mLof perchloric acid with water to 100mL.

Phenol Red TS(Phenolsulfonphthalein TS)— Dissolve 100mg of phenolsulfonphthalein in 100mLof alcohol,and filter if necessary.

pH4.7Phenol Red TS —Dissolve 33mg of phenolsulfonphthalein in 1.5mLof 2Nsodium hydroxide solution,dilute with water to 100mL,and mix (Solution A).Dissolve 25mg of ammonium sulfate in 235mLof water,add 105mLof 2Nsodium hydroxide solution and 135mLof 2Nacetic acid,and mix(Solution B).Add 25mLof Solution Ato Solution B,and mix.If necessary,adjust the pHof this solution to 4.7.

Phenoldisulfonic Acid TS —Dissolve 2.5g of phenol in 15mLof sulfuric acid in a flask of suitable capacity.Add 7.5mLof fuming sulfuric acid,stir well,and heat at 100for 2hours.Transfer the product,while still fluid,to a glass-stoppered bottle,and,when desired for use,warm in a water bath until liquefied.

Phenolphthalein TS —Dissolve 1g of phenolphthalein in 100mLof alcohol.

Phenylhydrazine Acetate TS —Dissolve 10mLof phenylhydrazine and 5mLof glacial acetic acid in water to make 100mL.

Phenylhydrazine–Sulfuric Acid TS —Dissolve 65mg of phenylhydrazine hydrochloride in 100mLof a cooled mixture of equal volumes of sulfuric acid and water.

Phloroglucinol TS —Dissolve 500mg of phloroglucinol in 25mLof alcohol.Store in tight containers,protected from light.

Phosphatic Enzyme TS —Dissolve 5g of phosphatic enzyme in water to make 50mL.Prepare this solution fresh.

Phosphomolybdic Acid TS —Dissolve 20g of phosphomolybdic acid in alcohol to make 100mL.Filter the solution,and use only the clear filtrate.

Phosphotungstic Acid TS —Dissolve 1g of phosphotungstic acid in water to make 100mL.

Picrate TS,Alkaline —Mix 20mLof trinitrophenol solution (1in 100)with 10mLof sodium hydroxide solution (1in 20),dilute with water to 100mL,and mix.Use within 2days.

Picric Acid TS —See Trinitrophenol TS.

Platinic Chloride TS —Dissolve 2.6g of platinic chloride in water to make 20mL.

Platinum–Cobalt TS —Dissolve 1.246g of potassium chloroplatinate (K2PtCl6)and 1.000g of cobalt chloride (CoCl2·6H2O)in water,add 100mLof hydrochloric acid,and dilute with water to 1L.

Potassium Pyroantimonate TS —Dissolve 2g of potassium pyroantimonate in 95mLof hot water.Cool quickly,and add a solution containing 2.5g of potassium hydroxide in 50mLof water and 1mLof sodium hydroxide solution (8.5in 100).Allow to stand for 24hours,filter,and dilute with water to 150mL.

Potassium Acetate TS —Dissolve 10g of potassium acetate in water to make 100mL.

Potassium–Bismuth Iodide TS —Dissolve 12.5g of tartaric acid in 25mLof water,then dissolve 1.06g of bismuth subnitrate in this mixture(Solution A).Dissolve 20g of potassium iodide in 25mLof water(Solution B).Dissolve 100g of tartaric acid in 450mLof water(Solution C).Add Solutions Aand Bto Solution C,and mix.

Potassium Carbonate TS —Dissolve 7g of anhydrous potassium carbonate in water to make 100mL.

Potassium Chromate TS —Dissolve 10g of potassium chromate in water to make 100mL.

Potassium Dichromate TS —Dissolve 7.5g of potassium dichromate in water to make 100mL.

Potassium Ferricyanide TS —Dissolve 1g of potassium ferricyanide in 10mLof water.Prepare this solution fresh.

Potassium Ferrocyanide TS —Dissolve 1g of potassium ferrocyanide in 10mLof water.Prepare this solution fresh.

Potassium Hydroxide TS —Dissolve 6.5g of potassium hydroxide in water to make 100mL.

Potassium Hydroxide TS,Alcoholic —Use 0.5N Potassium Hydroxide,Alcoholic(see in the section Volumetric Solutions).

Potassium Iodide TS —Dissolve 16.5g of potassium iodide in water to make 100mL.Store in light-resistant containers.

Potassium Iodide and Starch TS— Dissolve 0.75g of potassium iodide in 100mLof water.Heat to boiling,and add,with stirring,a solution of 0.5g of soluble starch in 35mLof water.Boil for 2minutes,and allow to cool.

Potassium Iodoplatinate TS —Dissolve 200mg of platinic chloride in 2mLof water,mix with 25mLof potassium iodide solution (1in 25),and add water to make 50mL.

Potassium Permanganate TS —Use 0.1N Potassium Permanganate(see in the section Volumetric Solutions).

Potassium Sulfate TS —Dissolve 1g of potassium sulfate in water to make 100mL.

Potassium Thiocyanate TS— Dissolve 9.7g of potassium thiocyanate in water to make 100mL.

Pyridine–Pyrazolone TS —To 100mLof a saturated solution of 1-phenyl-3-methyl-2-pyrazoline-5-one add 20mLof a 1in 1000solution of 3,3¢-dimethyl-1,1¢-diphenyl-[4,4¢-bi-2-pyrazoline]-5,5¢-dione in pyridine.Store in a dark bottle,and use within 3days.

Pyrogallol TS,Alkaline —Dissolve 500mg of pyrogallol in 2mLof water.Dissolve 12g of potassium hydroxide in 8mLof water.The solutions should be freshly prepared and mixed immediately before use.

Quinaldine Red TS —Dissolve 100mg of quinaldine red in 100mLof alcohol.

Quinone TS —Dissolve 500mg of p-benzoquinone in 2.5mLof glacial acetic acid,and dilute with alcohol to 50mL.Prepare this solution fresh daily.

Resorcinol TS —Dissolve 1g of resorcinol in hydrochloric acid to make 100mL.

Ruthenium Red TS —Dissolve 10g of lead acetate in water,dilute with water to 100mL,and add 80mg of ruthenium red.The solution is wine-red in color.[NOTE—If necessary,add additional ruthenium red to obtain a wine-red color.]

Saline TS —Dissolve 9.0g of sodium chloride in water to make 1000mL.

Saline TS,Pyrogen-Free —See Saline TS.

Schweitzer's Reagent —See Cupric Oxide,Ammoniated,TS.

Silver–Ammonia–Nitrate TS —Dissolve 1g of silver nitrate in 20mLof water.Add ammonia TS,dropwise,with constant stirring,until the precipitate is almost but not entirely dissolved.Filter,and store in tight,light-resistant containers.

Silver–Ammonium Nitrate TS —See Silver–Ammonia–Nitrate TS.

Silver Diethyldithiocarbamate TS —Dissolve 1g of silver diethyldithiocarbamate in 200mLof pyridine from a freshly opened bottle or that which has been recently distilled.Store in light-resistant containers,and use within 30days.

Silver Nitrate TS —Use 0.1N Silver Nitrate(see in the section Volumetric Solutions).

Simulated Gastric Fluid TS —See Gastric Fluid,Simulated,TS.

Simulated Intestinal Fluid TS —See Intestinal Fluid,Simulated,TS.

Sodium Acetate TS —Dissolve 13.6g of sodium acetate in water to make 100mL.

Sodium Alizarinsulfonate TS —Dissolve 100mg of sodium alizarinsulfonate in 100mLof water,and filter.

Sodium Aminoacetate TS(Sodium Glycinate TS)— Dissolve 3.75g of aminoacetic acid in about 500mLof water,add 2.1g of sodium hydroxide,and dilute with water to 1000mL.Mix 9mLof the resulting solution with 1mLof dilute glacial acetic acid (1in 300).This test solution has a pHbetween 10.4and 10.5.

Sodium Bisulfite TS —Dissolve 10g of sodium bisulfite in water to make 30mL.Prepare this solution fresh.

Sodium Bitartrate TS —Dissolve 1g of sodium bitartrate in water to make 10mL.Prepare this solution fresh.

Sodium Carbonate TS —Dissolve 10.6g of anhydrous sodium carbonate in water to make 100mL.

Sodium Chloride TS,Alkaline —Dissolve 2g of sodium hydroxide in 100mLof water,saturate the solution with sodium chloride,and filter.

Sodium Citrate TS —Dissolve 73.5g of sodium citrate dihydrate in water to make 250mL.

Sodium Cobaltinitrite TS —Dissolve 10g of sodium cobaltinitrite in water to make 50mL,and filter if necessary.

Sodium Fluoride TS —Dry about 500mg of sodium fluoride at 200for 4hours.Accurately weigh 222mg of the dried material,and dissolve in water to make 100.0mL.Pipet 10mLof this solution into a 1-Lvolumetric flask,and dilute with water to volume.Each mLof this solution corresponds to 0.01mg of fluorine (F).

Sodium Hydrosulfite TS,Alkaline —Dissolve 25g of potassium hydroxide in 35mLof water,and 50g of sodium hydrosulfite in 250mLof water.When the test solution is required,mix 40mLof the hydroxide solution with the 250mLof the hydrosulfite solution.Prepare this solution fresh.

Sodium Hydroxide TS —Dissolve 4.0g of sodium hydroxide in water to make 100mL.

Sodium Hypobromite TS —To a solution of 20g of sodium hydroxide in 75mLof water add 5mLof bromine.After solution has taken place,dilute with water to 100mL.Prepare this solution fresh.

Sodium Hypochlorite TS —Use Sodium Hypochlorite Solution(see in the section Reagent Specifications).

Sodium Iodohydroxyquinolinesulfonate TS —Dissolve 8.8g of iodohydroxyquinoline sulfonic acid in 200mLof water,and add 6.5mLof 4Nsodium hydroxide.Dilute with water to 250mL,mix,and filter.

Sodium Nitroferricyanide TS —Dissolve 1g of sodium nitroferricyanide in water to make 20mL.Prepare this solution fresh.

Dibasic Sodium Phosphate TS —Dissolve 12g of clear crystals of dibasic sodium phosphate in water to make 100mL.

Sodium Phosphotungstate TS —To a solution of 20g of sodium tungstate in 100mLof water add sufficient phosphoric acid to impart a strongly acid reaction to litmus,and filter.When required for use,decant the clear solution from any sediment that may be present.Store in tight,light-resistant containers.

Sodium Sulfide TS —Dissolve 1g of sodium sulfide in water to make 10mL.Prepare this solution fresh.

Sodium Tartrate TS —Dissolve 11.5g of sodium tartrate in water to make 100mL.

Sodium Tetraphenylboron TS —Dissolve 1.2g of sodium tetraphenylboron in water to make 200mL.If necessary,stir for 5minutes with 1g of freshly prepared hydrous aluminum oxide,and filter to clarify.

Sodium Thioglycolate TS —Dissolve 1.5g of sodium thioglycolate in 450mLof water,and add 50mLof alcohol.Use within 3days.

Sodium Thiosulfate TS —Use 0.1N Sodium Thiosulfate(see in the section Volumetric Solutions).

Standard Lead Solution —See under Heavy Metals á231ñ.

Stannous Chloride,Acid,TS —Dissolve 8g of stannous chloride in 500mLof hydrochloric acid.Store in glass containers,and use within 3months.

Stannous Chloride,Acid,Stronger,TS —Dissolve 40g of stannous chloride in 100mLof hydrochloric acid.Store in glass containers,and use within 3months.

Iodide-Free Starch TS —Mix 1g of soluble starch with sufficient cold water to make a thin paste.While stirring,add 100mLof boiling water,and allow to cool.Prepare this solution immediately before use.Iodide-free starch TSshows a blue color when 20mLof potassium iodide solution (1in 400)and 0.05mLof an iodine–potassium iodide solution (prepared by dissolving 127mg of iodine and 800mg of potassium iodide in water and diluting with water to 100mL)are added to 1mLof the iodide-free starch TS.

Starch Iodide Paste TS —Heat 100mLof water in a 250-mLbeaker to boiling,add a solution of 0.75g of potassium iodide in 5mLof water,then add 2g of zinc chloride dissolved in 10mLof water,and,while the solution is boiling,add,with stirring,a smooth suspension of 5g of soluble starch in 30mLof cold water.Continue to boil for 2minutes,then cool.Store in well-closed containers in a cold place.

Starch–Potassium Iodide TS —Dissolve 500mg of potassium iodide in 100mLof freshly prepared starch TS.Prepare this solution fresh.

Starch TS —Mix 1g of soluble starch with 10mg of red mercuric iodide and sufficient cold water to make a thin paste.Add 200mLof boiling water,and boil for 1minute with continuous stirring.Cool,and use only the clear solution.[NOTE—Commercially available,stabilized starch indicator solutions may be used.]

Stronger Cupric Acetate TS —See Cupric Acetate TS,Stronger.

Sudan III TS —Dissolve 0.05g of Sudan IIIin 25mLof alcohol,with warming if necessary.Cool,add 25mLof glycerin,and mix.Filter if undissolved material persists.

Sudan IV TS —Dissolve 0.5g of Sudan IVin chloroform to make 100mL.

Sulfanilic Acid TS —Dissolve 800mg of sulfanilic acid in 100mLof acetic acid.Store in tight containers.

Diazotized Sulfanilic Acid TS —Dissolve 0.9g of sulfanilic acid in 9mLof hydrochloric acid with warming,and dilute with water to 100mL.Cool 10mLof this solution in iced water,and add 10mLof a sodium nitrite solution (4.5in 100)previously cooled in iced water.Allow to stand at 0for at least 15minutes (the solution may be kept for 3days at this temperature).Immediately before use,add 20mLof sodium carbonate solution (1in 10).

Sulfanilic-a-Naphthylamine TS —See Sulfanilic-1-Naphthylamine TS.

Sulfanilic-1-Naphthylamine TS —Dissolve 500mg of sulfanilic acid in 150mLof acetic acid.Dissolve 100mg of 1-naphthylamine hydrochloride in 150mLof acetic acid,and mix the two solutions.The pink color that may develop on standing can be removed by treatment with zinc.

Sulfomolybdic Acid TS —Dissolve,with the aid of heat,2.5g of ammonium molybdate in 20mLof water,add 50mLof 12Nsulfuric acid,and dilute with water to 100mL.Store this solution in a polyethylene container.

Sulfuric Acid TS —Add a quantity of sulfuric acid of known concentration to sufficient water to adjust the final concentration to between 94.5%and 95.5%(w/w)of H2SO4.

Sulfuric Acid–Formaldehyde TS —Add 1drop of formaldehyde TSto each mLof sulfuric acid,and mix.Prepare this solution fresh.

Tannic Acid TS —Dissolve 1g of tannic acid in 1mLof alcohol,and dilute with water to 10mL.Prepare this solution fresh.

Tartaric Acid TS —Dissolve 3g of tartaric acid in water to make 10mL.Prepare this solution fresh.

Tetrabromophenolphthalein Ethyl Ester TS —Dissolve 100mg of tetrabromophenolphthalein ethyl ester in 90mLof glacial acetic acid,and dilute with glacial acetic acid to 100mL.Prepare this solution fresh.

Tetramethylammonium Hydroxide TS —Use an aqueous solution containing,in each 100mL,the equivalent of 10g of anhydrous tetramethylammonium hydroxide.

Thioacetamide TS —Dissolve 4g of thioacetamide in 100mLof water.

Thioacetamide–Glycerin Base TS —Mix 0.2mLof thioacetamide TSand 1mLof glycerin base TS,and heat in a boiling water bath for 20seconds.Use the mixture immediately.

Thorium Nitrate TS —Dissolve 1g of thorium nitrate in water to make 100mL.Filter,if necessary.

Thymol Blue TS —Dissolve 100mg of thymol blue in 100mLof alcohol,and filter if necessary.

Thymolphthalein TS —Dissolve 100mg of thymolphthalein in 100mLof alcohol,and filter if necessary.

Titanium Trichloride TS —Dissolve 15g of titanium trichloride in 100mLof 10%hydrochloric acid solution.

Titanium Trichloride–Sulfuric Acid TS —Mix carefully 20mLof titanium trichloride TSin 13mLof sulfuric acid.Add sufficient 30%hydrogen peroxide to produce a yellow color.Heat until white fumes are evolved,allow to cool,and dilute with water.Repeat the evaporation and addition of water until a colorless solution is obtained.Dilute with water to 100mL.

p-Toluenesulfonic Acid TS —Dissolve 2g of p-toluenesulfonic acid in 10mLof a mixture of 7parts of acetone and 3parts of water.

Triketohydrindene Hydrate TS(Ninhydrin TS)— Dissolve 200mg of triketohydrindene hydrate in water to make 10mL.Prepare this solution fresh.

Trinitrophenol TS(Picric Acid TS)— Dissolve the equivalent of 1g of anhydrous trinitrophenol in 100mLof hot water.Cool the solution,and filter if necessary.

Triphenyltetrazolium Chloride TS —Dissolve 500mg of triphenyltetrazolium chloride in dehydrated alcohol to make 100mL.

Xylenol Orange TS —Dissolve 100mg of xylenol orange in 100mLof alcohol.

Zinc Uranyl Acetate TS —Dissolve 50g of uranyl acetate in a mixture of 15mLof glacial acetic acid and water to make 500mL.Then dissolve 150g of zinc acetate in a mixture of 15mLof glacial acetic acid and water to make 500mL.Mix the two solutions,allow to stand overnight,and pass through a dry filter,if necessary.