Reagents, test solutions and volumetric solutions: S - Salbutamol RS.... Sulfurous acid TS

Salbutamol RS

International Chemical Reference Substance.

Salbutamol sulfate RS

International Chemical Reference Substance.

Salicylaldehyde R

C7H6O2.

Description.A clear, colourless, oily liquid; odour, bitter, almond-like.

Solubility.Slightly soluble in water; soluble in ethanol (~750 g/l) TS and ether R.

Relative density, = 1.17.

Salicylaldehyde TS

Procedure.Mix 2 g of salicylaldehyde R with 100 ml of methanol R and add 0.1 ml of hydrocloric acid (~420 g/l) TS.

Salicylic acid R.

2-hydroxybenzoic acid; C7H6O3.

A commercially available reagent of suitable grade.

Storage. Keep protected from light.

Saline TS

A sterile solution of sodium chloride R containing about 9 g/l of NaCl. Sterilization by heating in a steam autoclave at 120 °C for 30 minutes is suitable.

Saquinavir mesilate RS

International Chemical Reference Substance.

Saquinavir RS

International Chemical Reference Substance.

Selenious acid R

H2SeO3. Contains not less than 93% of H2SeO3.

Description.Colourless or white crystals.

Solubility.Soluble in water and ethanol (~750 g/l) TS.

Assay.Transfer about 0.1 g, accurately weighed, to a glass-stoppered flask and dissolve in 50 ml of water. Add 10 ml of potassium iodide (300 g/l) TS and 5 ml ofhydrochloric acid (~420 g/l) TS, mix, insert the stopper into the flask and allow to stand for 10 minutes. Dilute with 50 ml of water, add 3 ml of starchTS and titrate with sodium thiosulfate (0.1 mol/l) VS until the colour is no longer diminished, then titrate with iodine (0.05 mol/l) VS to a blue colour.Subtract the volume of iodine (0.05 mol/l) VS from the volume of sodium thiosulfate (0.1 mol/l) VS equivalent to selenious acid. Each ml of sodiumthiosulfate (0.1 mol/l) VS is equivalent to 3.225 mg of H2SeO3.

Note:Selenious acid R effloresces in dry air and is hygroscopic in moist air.

Selenious acid/sulfuric acid TS

Procedure.Dissolve 10 mg of selenious acid R in 2 ml of sulfuric acid (~1760 g/l) TS.

Selenium R

Se (SRIP, 1963, p. 172).

Caution. Selenium vapours are toxic.

Silica gel for chromatography R

A very finely divided (310 μm) silica gel. The particle size is indicated after the name of the reagent in the tests where it is used.

Description. A fine, white, homogeneous powder.

Solubility. Practically insoluble in water and ethanol (~750 g/l) TS.

Silica gel R1

Silica gel G.

Description.A white, homogeneous powder.

Composition.A mixture of silica gel (particle size 1040 μm) and calcium sulfate, hemihydrate (about 130 g/kg).

Silica gel R2

Silica gel HF(UV254).

Description.A white, homogeneous powder.

Composition.Silica gel (particle size 1040 μm) containing a fluorescent indicator having an optimal intensity at 254 nm (about 15 g/kg).

Silica gel R3

Silica gel H.

Description.A white, homogeneous powder.

Particle size.1040 μm.

Silica gel R4

Silica gel GF (UV 254).

Description.A white, homogeneous powder.

Composition.A mixture of silica gel (particle size 1040 μm) and calcium sulfate, hemihydrate (about 130 g/kg) containing a fluorescent indicatorhaving an optimal intensity at 254 nm (about 15 g/kg).

Silica gel R5

Silica gel 60.

Description.A white, homogeneous powder.

Average pore size.6 nm.

Silica gel R6

Silica gel 60 (UV 254).

Description.A white, homogeneous powder.

Average pore size.6 nm.

Composition.Silica gel (average particle size 15 μm) containing a fluorescent indicator having an optimal intensity at 254 nm (about 15 g/kg).

Silica gel for chromatography, hexadecylamidylsilyl

Particles of silica gel, the surface of which has been modified with chemically-bonded hexadecylamidylsilyl groups.

Silica gel for chromatography, octadecylsilyl, base deactivated

A very finely divided silica gel, pretreated before the bonding of octadecylsilyl groups to minimize the interaction with basic compounds.

Silica gel, desiccant, R

Description.An amorphous, partly hydrated SiO2, occurring in glassy granules of varying sizes. It is frequently coated with a substance that changes colourwhen the capacity to absorb water is exhausted. Such coloured products may be regenerated (i.e. may regain their capacity to absorb water) by heating at110 °C until the gel assumes the original colour.

Loss on ignition.Ignite 2 g, accurately weighed, at 950 ± 50 °C to constant weight; the loss is not more than 60 mg/g.

Water absorption.Place about 10 g in a tared weighing-bottle and weigh. Then place the bottle, with the cover removed, for 24 hours in a closed container in which theatmosphere is maintained at 80% relative humidity by being in equilibrium with sulfuric acid having a relative density of 1.19. Weigh again; the increasein weight is not less than 310 mg/g.

Silver nitrate (0.001 mol/l) VS

Silver nitrate R, dissolved in water to contain 0.1699 g of AgNO3 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under "Silver nitrate (0.1 mol/l) VS".

Silver nitrate (0.01 mol/l) VS

Silver nitrate R, dissolved in water to contain 1.699 g of AgNO3 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under silver nitrate (0.1 mol/l) VS.

Silver nitrate (0.05 mol/l) VS

Silver nitrate R, dissolved in water to contain 8.494 g of AgNO3 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under "Silver nitrate (0.1 mol/l) VS".

Silver nitrate (0.1 mol/l) VS

Silver nitrate R, dissolved in water to contain 16.99 g of AgNO3 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the 0.1 mol/l solution in the following manner: Dilute 40.0 ml of the silver nitrate solution with 100 ml of water.Heat the solution and add slowly, with continuous stirring, hydrochloric acid (~70 g/l) TS until precipitation of the silver is complete. Boil the mixturecautiously for about 5 minutes, then allow it to stand in the dark until the precipitate has settled and the supernatant liquid has become clear. Transferthe precipitate completely to a tared filtering crucible and wash it with small portions of water that have been slightly acidified with nitric acid (~1000g/l) TS. Dry the precipitate to constant weight at 110 °C. From the weight of silver chloride calculate the concentration of the silver nitrate solution inmol/l. Protect the silver chloride from light as much as possible during the determination.

Silver nitrate (100 g/l) TS

A solution of silver nitrate R containing 100 g of AgNO3 per litre.

Silver nitrate (40 g/l) TS

A solution of silver nitrate R containing about 42.5 g/l of AgNO3 (approximately 0.25 mol/l).

Silver nitrate R

AgNO3 (SRIP, 1963, p. 173).

Silver nitrate/methanol TS

Procedure.Prepare a saturated solution of silver nitrate R in methanol R.

Silver oxide R

Ag2O.

Description.A brownish-black, heavy powder; odourless.

Solubility.Practically insoluble in water; freely soluble in nitric acid (~130 g/l) TS and ammonia (~260 g/l) TS.

Substances insoluble in nitric acid.Dissolve 5 g in a mixture of 5 ml of nitric acid (~1000 g/l) TS and 10 ml of water, dilute to about 65 ml with water and filter any undissolved residue ona tared filtering crucible (retain the filtrate for the test for substances not precipitated by hydrochloric acid). Wash the crucible with water until thelast washing shows no opalescence with 1 drop of hydrochloric acid (~250 g/l) TS and dry to constant weight at 105 °C; not more than 0.2 mg/g.

Substances not precipitated by hydrochloric acid.Dilute the filtrate obtained in the test for substances insoluble in nitric acid to 250 ml with water, heat to boiling and add drop-wise sufficienthydrochloric acid (~250 g/l) TS to precipitate all of the silver (about 5 ml), avoiding any great excess. Cool, dilute to 300 ml with water and allow tostand overnight. Filter, evaporate 200 ml of the filtrate to dryness in a suitable tared porcelain dish and ignite; not more than 0.5 mg/g.

Alkalinity.Heat 2 g with 40 ml of water on a water-bath for 15 minutes, cool and dilute to 50 ml with water. Filter, discarding the first 10 ml of the filtrate. To 25ml of the subsequent filtrate add 2 drops of phenolphthalein/ethanol TS and titrate with hydrochloric acid (0.02 mol/l) VS to the disappearance of any pinkcolour; not more than 0.20 ml is required.

Silver standard (5 μg Ag/ml) TS

Procedure.Dissolve 39.5 mg of silver nitrate R in sufficient water to produce 100 ml. Dilute 1.0 ml of this solution to 100 ml with water.

Soda lime R

(SRIP, 1963, p. 174).

Sodium 1,2-naphthoquinone-4-sulfonate (5 g/l) TS

A solution of sodium 1,2-naphthoquinone-4-sulfonate R containing about 5 g of C10H5NaO5S per litre.

Sodium 1,2-naphthoquinone-4-sulfonate R

C10H5NaO5S.

Description.A yellow or orange, crystalline powder.

Solubility.Soluble in water; insoluble in ethanol (~750 g/l) TS.

Sodium acetate (0.04 mol/l) VS

Sodium acetate R, dissolved in water to contain 3.281 g of C2H3NaO2 in 1000 ml.

Sodium acetate (150 g/l) TS

A solution of sodium acetate R containing about 150 g/l of C2H3NaO2.

Sodium acetate (50 g/l) TS

A solution of sodium acetate R containing about 50 g of C2H3NaO2 per litre.

Sodium acetate (60 g/l) TS

A solution of sodium acetate R containing about 60 g of C2H3NaO2 per litre.

Sodium acetate R

C2H3NaO2,3H2O. Contains not less than 99.0% of C2H3NaO2,3H2O.

Description.Colourless crystals.

Solubility.Very soluble in water; sparingly soluble in ethanol (~750 g/l) TS.

Clarity and colour of solution.A 0.1 g/ml solution is clear and colourless.

pH value.pH of a 50 mg/ml solution, 7.59.2.

Iron.Use 8 g; the solution complies with the 2.2.4 Limit test for iron; not morethan 5.0 μg/g.

Heavy metals. Use 1.0 g for the preparation of the test solution as described in 2.2.3 Limit test for heavy metals, Procedure 1; determine the heavy metalscontent according to Method A; not more than 10 μg/g.

Substances reducing permanganate.Dissolve 1 g in 100 ml of boiling water, add 2 ml of sulfuric acid (~100 g/l) TS and 0.05 ml of potassium permanganate (0.02 mol/l) VS and boil for 5minutes; the pink colour does not entirely disappear.

Assay.Dissolve about 0.4 g, accurately weighed, in 100 ml of glacial acetic acid R and 5 ml of acetic anhydride R. After 5 minutes add 10 drops of 1-naphtholbenzein/acetic acid TS and titrate to a green end-point with perchloric acid (0.1 mol/l) VS as described under 2.6 Non-aqueous titration, Method A. Each ml of perchloric acid (0.1 mol/l) VS isequivalent to 13.61 mg of C2H3NaO2,3H2O.

Sodium acetate/glacial acetic acid (0.1 mol/l) VS

Procedure.Dissolve 5.3 g of anhydrous sodium carbonate R in small portions in 100 ml of glacial acetic acid R1, stirring well after each addition and add sufficientglacial acetic acid R1 to produce 1000 ml.

Method of standardization. Ascertain the exact concentration of the solution in the following manner: Titrate the solution against 15.0 ml of perchloric acid (0.1 mol/l) VS using 23 drops of crystal violet/acetic acid TS. Each ml of perchloric acid (0.1 mol/l) VS is equivalent to 8.203 mg of C2H3NaO2.

Sodium alizarinsulfonate (1 g/l) TS

Procedure.Dissolve 0.11 g of sodium alizarinsulfonate R in sufficient water to produce 100 ml.

Sodium alizarinsulfonate (10 g/l) TS

A solution of sodium alizarinsulfonate R containing about 10 g of C14H7NaO7S per litre.

Sodium alizarinsulfonate R

Alizarin Red S, sodium salt of 3,4-dihydroxy-9,10-anthraquinone-2-sulfonic acid; C14H7NaO7S,H2O.

Description.A yellow-brown or orange-yellow powder.

Solubility.Freely soluble in water, producing a yellow solution; sparingly soluble in ethanol (~750 g/l) TS.

Sodium amidotrizoate RS

International Chemical Reference Substance.

Sodium arsenite (0.05 mol/l) VS

Procedure.Dissolve 5 g of arsenic trioxide R in a mixture of 20 ml of sodium hydroxide (~80 g/l) TS and 20 ml of water, dilute to 400 ml with water and addhydrochloric acid (~70 g/l) TS until the solution is neutral to litmus paper R. Dissolve 4 g of sodium hydrogen carbonate R in the prepared solution anddilute to 1000 ml with water.

Method of standardization.Ascertain the exact concentration of the 0.05 mol/l solution in the following manner; dilute 25 ml with 50 ml of water, add 5 g of sodium hydrogencarbonate R and titrate with iodine (0.05 mol/l) VS, using starch TS as indicator.

Storage.Add 1 drop of mercury R for the preservation of the solution.

Sodium arsenite (0.1 mol/l) VS

Procedure.Dissolve 5 g of arsenic trioxide R in a mixture of 20 ml of sodium hydroxide (~80 g/l) TS and 20 ml of water, dilute to 400 ml with water and addhydrochloric acid (~70 g/l) TS until the solution is neutral to litmus paper R. Dissolve 2 g of sodium hydrogen carbonate R in the prepared solution anddilute to 500 ml with water.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sodium arsenite (0.05 mol/l) VS.

Storage.Add 1 drop of mercury R for the preservation of the solution.

Sodium carbonate (10 g/l) TS

A solution of sodium carbonate R containing about 10.6 g of Na2CO3 per litre (approximately 0.1 mol/l).

Sodium carbonate (200 g/l) TS

A solution of sodium carbonate R containing 200 g of Na2CO3 per litre.

Sodium carbonate (50 g/l) TS

A solution of sodium carbonate R containing about 50 g/l of Na2CO3 (approximately 0.5 mol/l).

Sodium carbonate (75 g/l) TS

A solution of sodium carbonate R containing about 75 g of Na2CO3 per litre.

Sodium carbonate R

Na2CO3,10H2O (SRIP, 1963, p. 179).

Sodium carbonate standard TS

Procedure.Dissolve 2.64 g of sodium carbonate R and 2.093 g of sodium hydrogen carbonate R in sufficient carbon-dioxide-free water R to produce 1000 ml.

Sodium carbonate, anhydrous, FeR

Anhydrous sodium carbonate R that complies with the following additional test: Dissolve 4.0 g in 25 ml of water, add 8 ml of hydrochloric acid (~250 g/l)FeTS and proceed with the 2.2.4 Limit test for iron, using 2 ml of ironstandard FeTS; not more than 10 μg/g.

Sodium carbonate, anhydrous, R

Na2CO3 (SRIP, 1963, p. 179).

Sodium chloride (10 g/l) TS

A solution of sodium chloride R containing about 10 g of NaCl per litre.

Sodium chloride (300g/l) TS

A solution of sodium chloride R containing about 300 g of NaCl per litre.

Sodium chloride (400 g/l) TS

A saturated solution of sodium chloride R containing about 400 g of NaCl per litre.

Sodium chloride (9 g/l) TS

A solution of sodium chloride R containing about 9g of NaCl per litre.

Sodium chloride R

NaCl (SRIP, 1963, p. 181).

Sodium chloride, pyrogen-free, R

Sodium chloride R which complies with the following additional test:

Pyrogens.Carry out the test as described under 3.5 Test for pyrogens injecting, per kg ofthe rabbit's weight, a solution containing 9 mg in 10 ml of sterile water R.

Sodium citrate (250 g/l) TS

A solution of sodium citrate R containing about 294 g of C6H5Na3O7,2H2O in 1000 ml.

Sodium citrate R.

C6H5Na3O7,2H2O.

Contains not less than 99.0% of C6H5Na3O7, calculated with reference to the anhydrous substance.

Description.White, granular crystals or a crystalline powder; odourless. Slightly deliquescent in moist air.

Solubility.Soluble in less than 2 parts of water, practically insoluble in ethanol (~750 g/l) TS.

Appearance of solution.A 100 g/l solution is clear and colourless.

Water.Determined by the Karl Fischer method, keeping the substance in contact with the dehydrated methanol R for 15 minutes; not less than 110 mg/g and not morethan 130 mg/g.

Assay. Dissolve about 0.15 g, accurately weighed, in 20 ml of glacial acetic acid R and titrate with perchloric acid (0.1 mol/l) VS as described in 2.6 Non-aqueous titration, Method A. Each ml of perchloric acid (0.1 mol/l) VS isequivalent to 8.603 mg of C6H5Na3O7.

Sodium cobaltinitrite (100 g/l) TS

A solution of sodium cobaltinitrite R containing about 100 g/l of Na3Co(NO2)6.

Sodium cobaltinitrite R

Na3Co(NO2)6 (SRIP, 1963, p. 182).

Sodium cromoglicate RS

International Chemical Reference Substance.

Sodium diethyldithiocarbamate (0.8 g/l) TS

A solution of sodium diethyldithiocarbamate R containing about 0.8 g of C5H10NNaS2 per litre.

Sodium diethyldithiocarbamate R

C5H10NNaS2,3H2O (SRIP, 1963, p. 183).

Sodium dihydrogen phosphate (275 g/l) TS

A solution of sodium dihydrogen phosphate R containing about 275 g of NaH2PO4 per litre.

Sodium dihydrogen phosphate (45 g/l) TS

A solution of sodium dihydrogen phosphate R containing about 47 g of NaH2PO4 per litre.

Sodium dihydrogen phosphate, anhydrous R

Molecular formula:NaH2PO4

Description:White powder, hygroscopic.

Storage:in a tightly closed container.

Sodium dihydrogen phosphate dihydrate R

[sodium biphosphate]; sodium phosphate, monobasic; NaH2 PO4, 2 H2O.

Sodium dihydrogen phosphate R

[sodium biphosphate]; sodium phosphate, monobasic; NaH2PO4,H2O (SRIP, 1963, p. 178).

Sodium dithionite R

Sodium hydrosulfite, sodium sulfoxylate; Na2O4S2.

Description. A white or greyish white, crystalline powder.

Solubility. Very soluble in water, slightly soluble in ethanol (~750 g/l) TS.

Note: Sodium dithionite R oxidizes in air.

Sodium dithionite (200g/l) TS

A solution of sodium dithionite R containing about 200 g of Na2O4S2 per litre.

Sodium dodecyl sulfate R.

Sodium lauryl sulfate; C12H25NaO4S.

Purified grade of commercially available reagent containing not less than 99.0% of C12H25NaO4S.

White, crystalline flakes.

Sodium fluoride R

NaF (SRIP, 1963, p. 183).

Sodium formate R

CHNaO2.

Description.White, deliquescent granules or a crystalline powder; slight odour of formic acid.

Melting temperature.About 253 °C.

Sodium hexanesulfonate R

C6H13NaO3S.

A commercially available reagent of suitable grade.

Sodium hydrogen carbonate (100 g/l) TS

A solution of sodium hydrogen carbonate R containing about 100 g of NaHCO3 in 1000 ml.

Sodium hydrogen carbonate (40 g/l) TS

A solution of sodium hydrogen carbonate R containing about 42 g of NaHCO3 per litre (approximately 0.5 mol/l).

Sodium hydrogen carbonate R

[sodium bicarbonate]; NaHCO3 (SRIP, 1963, p. 177).

Sodium hydrogen carbonate R

NaHCO3 (SRIP, 1963, p. 177).

Sodium hydroxide (~150 g/l) TS

A solution of sodium hydroxide R containing about 150 g of NaOH per litre.

Sodium hydroxide (~200 g/l) TS

A solution of sodium hydroxide R containing about 200 g/l of NaOH.

Sodium hydroxide (~300 g/l) TS

A solution of sodium hydroxide R containing about 300 g/l of NaOH.

Sodium hydroxide (~400 g/l) TS

A solution of sodium hydroxide R containing about 400 g/l of NaOH.

Sodium hydroxide (~80 g/l) TS

A solution of sodium hydroxide R containing about 80 g/l of NaOH (approximately 2 mol/l).

Sodium hydroxide (~40 g/l) TS

A solution of sodium hydroxide R containing about 40 g/l of NaOH (approximately 1 mol/l).

Sodium hydroxide (0.001 mol/l) VS

Sodium hydroxide R, dissolved in water to contain 40.01 mg of NaOH in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sodium hydroxide (1 mol/l) VS.

Sodium hydroxide (0.01 mol/l) VS

Sodium hydroxide R, dissolved in water to contain 0.4001 g of NaOH in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sodium hydroxide (1 mol/l) VS.

Sodium hydroxide (0.01 mol/l), carbonate-free, VS

Sodium hydroxide R, dissolved in water to contain 0.4001 g of NaOH in 1000 ml.

Procedure, test for carbonates and method of standardization. Prepare the solution, carry out the test and ascertain the exact concentration following the method described under carbonate-free sodium hydroxide (1mol/l) VS.

Sodium hydroxide (0.02 mol/l) VS

Sodium hydroxide R, dissolved in water to contain 0.8001 g of NaOH in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sodium hydroxide (1 mol/l) VS.

Sodium hydroxide (0.02 mol/l), carbonate-free, VS

Sodium hydroxide R, dissolved in water to contain 0.8001 g of NaOH in 1000 ml.

Procedure, test for carbonates and method of standardization. Prepare the solution, carry out the test and ascertain the exact concentration following the method described under carbonate-free sodium hydroxide (1mol/l) VS.

Sodium hydroxide (0.05 mol/l) VS

Sodium hydroxide R, dissolved in water to contain 2.000 g of NaOH in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sodium hydroxide (1 mol/l) VS.

Sodium hydroxide (0.1mol/l) BET

Prepare from sodium hydroxide R and water BET. It is suitable if, after adjustment to pH 6.57.5, it gives a negative result under theconditions prescribed in the 3.4 Test for bacterial endotoxins.

Sodium hydroxide (0.1 mol/l) VS

Sodium hydroxide R, dissolved in water to contain 4.001 g of NaOH in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sodium hydroxide (1 mol/l) VS.

Sodium hydroxide (0.1 mol/l), carbonate-free, VS

Sodium hydroxide R, dissolved in water to contain 4.001 g of NaOH in 1000 ml.

Procedure, test for carbonates and method of standardization. Prepare the solution, carry out the test and ascertain the exact concentration following the method described under carbonate-free sodium hydroxide (1mol/l) VS.

Sodium hydroxide (0.2 mol/l) VS

Sodium hydroxide R, dissolved in water to contain 8.001 g of NaOH in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sodium hydroxide (1 mol/l) VS.

Sodium hydroxide (0.2 mol/l), carbonate-free, VS

Sodium hydroxide R, dissolved in water to contain 8.001 g of NaOH in 1000 ml.

Procedure, test for carbonates and method of standardization. Prepare the solution, carry out the test and ascertain the exact concentration following the method described under carbonate-free sodium hydroxide (1mol/l) VS.

Sodium hydroxide (0.5 mol/l) VS

Sodium hydroxide R, dissolved in water to contain 20.00 g of NaOH in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sodium hydroxide (1 mol/l) VS.

Sodium hydroxide (0.5 mol/l), carbonate-free, VS

Sodium hydroxide R, dissolved in water to contain 20.00 g of NaOH in 1000 ml.

Procedure, test for carbonates and method of standardization. Prepare the solution, carry out the test and ascertain the exact concentration following the method described under carbonate-free sodium hydroxide (1mol/l) VS.

Sodium hydroxide (1 mol/l) VS

Sodium hydroxide R, dissolved in water to contain 40.01 g of NaOH in 1000 ml.

Method of standardization.Ascertain the exact concentration of the 1 mol/l solution in the following manner: Dry about 5 g of potassium hydrogen phthalate R at 105 °C for 3 hoursand weigh accurately. If the potassium hydrogen phthalate is in the form of large crystals, they should be crushed before drying. Dissolve in 75 ml ofcarbon-dioxide-free water R and titrate with the sodium hydroxide solution, using phenolphthalein/ethanol TS as indicator. Each 0.2042 g of potassiumhydrogen phthalate is equivalent to 1 ml of sodium hydroxide (1 mol/l) VS. Standard solutions of sodium hydroxide should be restandardized frequently.

Storage.Solutions of alkali hydroxides absorb carbon dioxide when exposed to air. They should therefore be stored in bottles with suitable non-glass, well-fittingstoppers, provided with a tube filled with soda lime R.

Sodium hydroxide (1 mol/l), carbonate-free, VS

Sodium hydroxide R, dissolved in water to contain 40.01 g of NaOH in 1000 ml.

Procedure.Dissolve sodium hydroxide R in water to produce a 400-600 g/l solution and allow to stand. Taking precautions to avoid absorption of carbon dioxide, siphonoff the clear supernatant liquid and dilute as required with carbon-dioxide-free water R.

Test for carbonates.Titrate 45 ml of hydrochloric acid (1 mol/l) VS with the carbonate-free sodium hydroxide solution, using phenolphthalein/ethanol TS as indicator. At theend-point add just sufficient acid to discharge the pink colour and boil to reduce the volume to 20 ml. Add, whilst boiling, sufficient acid again todischarge the pink colour and prevent its reappearance on continued boiling; not more than 0.1 ml of the acid is required.

Method of standardization.Ascertain the exact concentration of the 1 mol/l solution in the following manner: Dry about 5 g of potassium hydrogen phthalate R at 105 °C for 3 hoursand weigh accurately. If the potassium hydrogen phthalate is in the form of large crystals they should be crushed before drying. Dissolve in 75 ml ofcarbon-dioxide-free water R and titrate with the carbonate-free sodium hydroxide solution, using phenolphthalein/ethanol TS as indicator. Each 0.2042 g ofpotassium hydrogen phthalate is equivalent to 1 ml of carbonate-free sodium hydroxide (1 mol/l) VS. Standard solutions of sodium hydroxide should berestandardized frequently.

Storage.Solutions of alkali hydroxides absorb carbon dioxide when exposed to air. They should therefore be stored in bottles with suitable non-glass, well-fittingstoppers, provided with a tube filled with soda lime R.

Sodium hydroxide (10 g/l) TS

A solution of sodium hydroxide R containing about 10 g of NaOH per litre (approximately 0.25 mol/l).

Sodium hydroxide (50 g/l) TS

A solution of sodium hydroxide R containing about 50 g of NaOH per litre.

Sodium hydroxide R

NaOH (SRIP, 1963, p. 185).

Sodium hydroxide/ethanol TS

Procedure.Dissolve 50 g of sodium hydroxide R in sufficient ethanol (~750 g/l) TS to produce 1000 ml.

Sodium hydroxide/methanol TS

Procedure.Dissolve 40 g of sodium hydroxide R in sufficient methanol R to produce 1000 ml.

Sodium hypobromite TS

Procedure. Dissolve 2.5 g of sodium hydroxide R in 7.5 ml of water, add 0.5ml of bromine R and a sufficient quantity of water to produce 10 ml.

Note: Sodium hypobromite TS must be freshly prepared.

Sodium hypochlorite (~40 g/l) TS

Description.A pale, greenish yellow, clear liquid; odour, resembling that of chlorine.

Assay.Introduce 3 ml into a glass-stoppered flask, weigh accurately and add 50 ml of water. Add 2 g of potassium iodide R and 10 ml of acetic acid (~300 g/l) TSand titrate the liberated iodine with sodium thiosulfate (0.1 mol/l) VS, adding 3 ml of starch TS as the end-point is approached. Each ml of sodiumthiosulfate (0.1 mol/l) VS is equivalent to 3.723 mg of NaOCl.

Storage.Sodium hypochlorite (~40 g/l) TS must be kept in a light-resistant container at a temperature not exceeding 25 °C.

Sodium hypochlorite TS1

Procedure.Dilute 10 ml of sodium hypochlorite (~40 g/l) TS to 100 ml with water (contains approximately 0.5% of chlorine).

Sodium iodide R

NaI.

Description. White crystalline powder or colourless crystals, hygroscopic.

Solubility. Very soluble in water, freely soluble in alcohol.

Sodium laurilsulfate (10 g/l) TS

A solution of sodium laurilsulfate R containing about 10 g of C12H25NaO4S per litre.

Sodium laurilsulfate R

Sodium lauryl sulfate; a mixture of sodium alkyl sulfates, consisting mainly of sodium dodecyl sulfates, C12H25NaO4S.

Description. A white or pale yellow powder, crystals, or flakes; odour, faint but characteristic.

Solubility.Very soluble in water giving an opalescent solution; partly soluble in ethanol (~750 g/l) TS.

Sodium mercaptoacetate R

(Sodium thioglycolate R.) C2H3NaO2S.

Description.Hygroscopic crystals.

Solubility.Freely soluble in water; slightly soluble in ethanol (~750 g/l) TS.

Sodium metabisulfite (50 g/l) TS

A solution of sodium metabisulfite R containing about 50 g of Na2O5S2 per litre.

Sodium metabisulfite R

Na2O5S2 (SRIP, 1963, p. 187).

Sodium metaperiodate R

Sodium periodate NaIO4. Contains not less than 98.0% of NaIO4.

Description.White crystals or a white, crystalline powder.

Solubility.Soluble in water.

Assay.Dissolve 0.5 g in 100 ml of water. Add 3 g of sodium hydrogen carbonate R and 3 g of potassium iodide R, and titrate the liberated iodine with sodiumarsenite (0.05 mol/l) VS. Each ml of sodium arsenite (0.05 mol/l) VS is equivalent to 10.69 mg of NaIO4.

Sodium metaperiodate TS

Procedure. Dissolve 60 g of sodium metaperiodate R in 120 ml of sulfuric acid (0.05 mol/l) VS and dilute to 1000 ml with water. Do not heat to dissolve the periodate. If the solution is not clear, filter through a sintered-glass filter. Store the solution in aglass-stoppered, light-resistant container.

Suitability test.Pipette 10 ml into a 250 ml volumetric flask, dilute to volume with water and mix. To about 550 mg of glycerol R dissolved in 50 ml of water add, using apipette, 50 ml of the diluted sodium metaperiodate. For a blank, transfer 50 ml of the diluted sodium metaperiodate solution to a flask containing 50 ml ofwater. Allow the solutions to stand for 30 minutes, then to each add 5 ml of hydrochloric acid (~420 g/l) TS and 10 ml of potassium iodide (80 g/l) TS andswirl to mix. Allow to stand for 5 minutes, add 100 ml of water and titrate with sodium thiosulfate (0.1 mol/l) VS, shaking continuously and adding 3 ml ofstarch TS as the end-point is approached. The ratio of the volume of sodium thiosulfate (0.1 mol/l) VS required for sodium metaperiodate TS to thatrequired for the blank should be between 0.750 and 0.765.

Sodium methoxide (0.1 mol/l) VS

Procedure.Cool in ice-water 150 ml of dehydrated methanol R and add in small portions 2.5 g of freshly cut sodium R. When the metal has dissolved, add sufficienttoluene R to produce 1000 ml.

Method of standardization.Ascertain the exact concentration of the 0.1 mol/l solution in the following manner: Titrate 0.10 g of benzoic acid R, accurately weighed, as described under 2.6 Non-aqueous titration, Method B. Each 12.21 mg of C7H6O6 is equivalent to 1 ml of sodium methoxide (0.1 mol/l) VS.

Note:Sodium methoxide (0.1 mol/l) VS must be standardized immediately before use.

Sodium molybdotungstophosphate TS

Procedure.Boil under a reflux condenser for 2 hours 350 ml of water with 50 g of sodium tungstate R, 12 g of phosphomolybdic acid R and 25 ml of phosphoric acid(~1440 g/l) TS; cool and add sufficient water to produce 500 ml.

Sodium nitrate R

NaNO3.

A commercially available reagent of suitable grade.

Sodium nitrite (0.1 mol/l) VS

Sodium nitrite R, dissolved in water to contain 6.900 g of NaNO2 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the 0.1 mol/l solution in the following manner: Place 50.0 ml of potassium permanganate (0.02 mol/l) VS in aglass-stoppered flask, dilute with 300 ml of water, add 25 ml of sulfuric acid (~100 g/l) TS and 20.0 ml of the sodium nitrite solution. Allow the solutionto stand for 10 minutes. Then add 2 g of potassium iodide R and titrate with sodium thiosulfate (0.1 mol/l) VS, using starch TS as indicator. Perform ablank determination and make any necessary corrections.

Sodium nitrite (1 g/l) TS

A solution of sodium nitrite R containing about 1 g of NaNO2 per litre.

Note:Sodium nitrite (1 g/l) TS must be freshly prepared.

Sodium nitrite (10 g/l) TS

A solution of sodium nitrite R containing about 10 g/l of NaNO2.

Sodium nitrite (100 g/l) TS

A solution of sodium nitrite R containing about 100 g of NaNO2 per litre.

Sodium nitrite (20 g/l) TS

A solution of sodium nitrite R containing about 20 g of NaNO2 per litre.

Sodium nitrite (3 g/l) TS

A solution of sodium nitrite R containing about 3 g of NaNO2 per litre.

Note:Sodium nitrite (3 g/l) TS must be freshly prepared.

Sodium nitrite (35 g/l) TS

A solution of sodium nitrite R containing about 35 g of NaNO2 per litre (approximately 0.5 mol/l).

Sodium nitrite (50 g/l) TS

A solution of sodium nitrite R containing about 50 g of NaNO2 per litre.

Sodium nitrite R

NaNO2 (SRIP, 1963, p. 189).

Sodium nitrite/hydrochloric acid TS

Procedure.Dissolve 0.5 g of sodium nitrite R in sufficient hydrochloric acid (0.1 mol/l) VS to produce 100 ml.

Sodium nitroprusside (45 g/l) TS

A solution of sodium nitroprusside R containing about 45 g of Na2Fe(NO)(CN)5 per litre.

Note:Sodium nitroprusside (45 g/l) TS must be freshly prepared.

Sodium nitroprusside (8.5 g/l) TS

A solution of sodium nitroprusside R containing about 8.5 g of Na2Fe(NO)(CN)5 per litre.

Sodium nitroprusside R

Na2Fe(NO)(CN)5,2H2O (SRIP, 1963, p. 190).

Sodium nitroprusside, alkaline, TS

Procedure.Dissolve 1 g of sodium nitroprusside R and 1 g of sodium carbonate R in sufficient water to produce 100 ml.

Sodium octanesulfonate R

C8H17NaO3S.

Contains not less than 98.0% of C8H17NaO3S.

A commercially available reagent of suitable grade.

Absorbance. A 0.05 g/ml solution of a 1 cm layer measured at a wavelength of about 250 nm has an absorbance of not greater than 0.01.

Sodium oxalate R

C2Na2O4 (SRIP, 1963, p. 190).

Sodium peroxide R.

Na2O2 (SRIP, 1963, p. 191).

Sodium phosphate, anhydrous, R

Sodium dihydrogen phosphate anhydrous; NaH2PO4.

A commercially available reagent of suitable grade.

Contains not less than 99.0% of NaH2PO4.

Sodium R

Na (SRIP, 1963, p. 175).

Sodium rhodizonate dibasic R

3,4,5,6-Tetraoxocyclohexene-1,2-diol; rhodizonic acid disodium salt; C6Na2O6.

A commercially available reagent of suitable grade.

Sodium salicyclate R

C7H5NaO3. Use sodium salicylate as described in the monograph for Sodium salicylate.

Sodium salicylate (11.5 g/l) TS

A solution of sodium salicylate R containing about 11.5 g of C7H5NaO3 per litre.

Sodium standard (200μ g Na/ml) TS

Procedure. Dissolve 0.5084 g of sodium chloride R, previously dried at 100105 °C for 3 hours, in sufficient water to produce 1000 ml.

Sodium sulfate, anhydrous, R

Na2SO4 (SRIP, 1963, p. 195).

Sodium sulfide R

Na2S,9H2O (SRIP, 1963, p. 195).

Sodium sulfide TS

Procedure.Dissolve 12 g of sodium sulfide R in 25 ml of water and add sufficient glycerol R to produce 100 ml.

Sodium sulfide (100 g/l) TS

Dissolve 1 g of sodium sulfide R in sufficient water R to produce 10 ml. Note: this solution must be freshly prepared.

Sodium sulfite R

Na2SO3,7H2O (SRIP, 1963, p. 196).

Sodium tetraborate (10 g/l) TS

A solution of sodium tetraborate R containing about 10 g of Na2B4O7 per litre.

Sodium tetraborate R

Borax, Na2B4O7,10H2O.

Description.Transparent, colourless crystals, or a white, crystalline powder; odourless.

Solubility.Soluble in 20 parts of water and in 0.6 part of boiling water; very slightly soluble in ethanol (~750 g/l) TS.

pH value of a 0.01 mol/l solution.Dissolve 0.3814 g in water and dilute to 100 ml, using water having a pH of 6.57.4. The pH should be from 9.15 to 9.20 at 25 °C.

Chlorides. Dissolve 1.0 g in 20 ml of water, filter if necessary through a chloride-free filter, add 1 ml of nitric acid (~1000 g/l) TS and proceed as described in 2.2.1 Limit test for chlorides. Sodium tetraborate R contains not more than250 μg/g.

Sulfates. Dissolve 0.5 g in 20 ml of water, add 2 ml of hydrochloric acid (~70 g/l) TS and filter. Proceed as described in 2.2.2 Limit test for sulfates. Sodium tetraborate R contains not more than1.0 mg/g.

Sodium tetraborate standard TS

Procedure.Dissolve 3.81 g of sodium tetraborate R in sufficient carbon-dioxide-free water R to produce 1000 ml.

Storage.Store the solution protected from atmospheric carbon dioxide and keep it stoppered at all times except when actually in use.

Sodium tetraphenylborate (30 g/l) TS

A solution of sodium tetraphenylborate R containing about 30 g/l of C24H20BNa.

Note:If necessary, stir for 5 minutes with 1 g of aluminium hydroxide R or charcoal R and filter to clarify.

Sodium thioglycolate R. See Sodium mercaptoacetate R.

Sodium tetraphenylborate R

C24H20BNa.

Description.A fluffy, white or almost white powder.

Solubility.Freely soluble in water and acetone R; insoluble in light petroleum R.

pH value.pH of a 20 g/l solution, not less than 7.5.

Sodium thiosulfate (0.002mol/l) VS

Sodium thiosulfate R, dissolved in water to contain 0.316 g of Na2S2O3 in 1000 ml.

Method of standardization. Ascertain the exact concentration of the solution following the method described under sodium thiosulfate (0.1 mol/l) VS.

Sodium thiosulfate (0.01 mol/l) VS

Sodium thiosulfate R, dissolved in water to contain 1.582 g of Na2S2O3 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution by following the method described under sodium thiosulfate (0.1 mol/l) VS.

Sodium thiosulfate (0.02 mol/l) VS

Sodium thiosulfate R, dissolved in water to contain 3.164 g of Na2S2O3 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sodium thiosulfate (0.1 mol/l) VS.

Sodium thiosulfate (0.05 mol/l) VS

Sodium thiosulfate R, dissolved in water to contain 7.910 g of Na2S2O3 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution by following the method described under sodium thiosulfate (0.1 mol/l) VS.

Sodium thiosulfate (0.1 mol/l) VS

Sodium thiosulfate R, dissolved in water to contain 15.82 g of Na2S2O3 in 1000 ml.

Method of standardization(alternative procedure). Ascertain the exact concentration of the 0.1 mol/l solution in the following manner: To about 40 ml of water in a glass-stopperedconical flask, add 10.0 ml of potassium bromate (0.0167 mol/l) VS, 1 g of potassium iodide R and 3 ml of sulfuric acid (~1760 g/l) TS. Allow the solutionto stand for 5 minutes and titrate the liberated iodine with the sodium thiosulfate solution, adding 3 ml of starch TS as the end-point is approached.Perform a blank determination on the same quantities of the reagents and make any necessary corrections.

Sodium thiosulfate (320 g/l) TS

A solution of sodium thiosulfate R containing about 320 g of Na2S2O3 per litre.

Sodium thiosulfate R

Na2S2O3,5H2O (SRIP, 1963, p. 197).

Sodium tungstate R

Na2O4W,2H2O (SRIP, 1963, p. 197).

Sorbitol R

C6H14O6. Contains not less than 97.0% of C6H14O6.

Description.White granules or powder or a white, crystalline mass.

Solubility.Very soluble in water; sparingly soluble in ethanol (~750 g/l) TS; practically insoluble in ether R.

Assay.Dissolve about 0.2 g, previously dried and accurately weighed, in sufficient water to produce 100 ml. Transfer 10.0 ml to an iodine flask, add 50.0 ml ofpotassium periodate TS and heat for 15 minutes on a water-bath. Cool, add 2.5 g of potassium iodide R, stopper tightly and shake well. Allow to stand for 5minutes protected from light and titrate with sodium thiosulfate (0.1 mol/l) VS, using 3 ml of starch TS as an indicator. Perform a blank titration andmake any necessary corrections. Each ml of sodium thiosulfate (0.1 mol/l) VS is equivalent to 1.822 mg of C6H14O6.

Storage.Store in a tightly closed container.

Spectinomycin hydrochloride RS

International Chemical Reference Substance.

Spironolactone RS

International Chemical Reference Substance.

Squalane R

2,6,10,15,19,23-Hexamethyltetracosane; C30H62.

Description.A colourless, oily liquid.

Solubility.Freely soluble in ether R; slightly soluble in acetone R and ethanol (~750 g/l) TS.

Relative density. = 0.811 - 0.813.

Refractive index. = 1.451 - 1.453.

Stannated hydrochloric acid (~ 250 g/l) AsTS

Refer to Hydrochloric acid (~250 g/l), stannated, AsTS.

Stannous chloride AsTS

Procedure.Prepare from stannous chloride TS by adding an equal volume of hydrochloric acid (~250 g/l) TS, boil down to the original volume and filter through afine-grained filter-paper.

Test for arsenic.To 10 ml add 6 ml of water and 10 ml of hydrochloric acid (~250 g/l) AsTS and distil 16 ml. To the distillate add 50 ml of water and 2 drops of stannouschloride AsTS; then apply the general test for arsenic. The colour of the stain produced is not more intense than that produced from a 1 ml standard stain,showing that the amount of arsenic does not exceed 1 μg/ml.

Stannous chloride R

SnCl2,2H2O (SRIP, 1963, p. 198).

Stannous chloride TS

Procedure. Dissolve 330 g of stannous chloride R in 100 ml of hydrochloric acid (~250 g/l) TS and sufficient water to produce 1000 ml.

Stannous chloride/hydrochloric acid TS1

Procedure.Dissolve 10 g of stannous chloride R in sufficient hydrochloric acid (~70 g/l) TS to produce 100 ml.

Starch iodide TS

Procedure. Dissolve 0.75 g of potassium iodide R in 5 ml of water and 2 g of zinc chloride R in 10 ml of water, mix the two solutions and add 100 ml of water. Heatthe solution to boiling and add, with constant stirring, a suspension of 5 g of corn or potato starch R in 35 ml of water. Boil for 2 minutes and cool.

Storage. Store in a well-closed container and keep in a cool place.

Starch R

[potato starch R or corn starch R] (SRIP, 1963, p. 199).

Starch TS

Procedure.Mix 0.5 g of starch R or of soluble starch R with 5 ml of water and add this solution, with constant stirring, to sufficient water to produce about 100 ml;boil for a few minutes, cool and filter.

Note:Starch TS must be freshly prepared.

Starch, soluble, R

(SRIP, 1963, p. 199).

Starch/iodide paper R

[starch-iodide paper R] (SRIP, 1963, p. 200).

Streptomycin sulfate RS

International Chemical Reference Substance.

Strontium chloride hexahydrate R

SrCl2,6H2O.

A commercially available reagent of suitable grade.

Contains not less than 99.0% and not more than 103.0% of SrCl2,6H2O.

Strychnine sulfate R

C42H44N4O4,H2SO4,5H2O (SRIP, 1963, p. 200).

Sudan red G R

1-(4-Phenylazophenylazo)-2-naphthol; Sudan III; Solvent red 23; C.I. 26100; C22H16N4O.

Description.A reddish brown powder.

Solubility.Practically insoluble in water.

Sudan red TS

Procedure.Dissolve 0.5 g of sudan red G R in 100 ml of glacial acetic acid R1.

Sulfacetamide RS

International Chemical Reference Substance.

Sulfadiazine RS

International Chemical Reference Substance.

Sulfadimidine RS

International Chemical Reference Substance.

Sulfadoxine RS

International Chemical Reference Substance.

Sulfamethoxazole R

4-Amino-N-(5-methylisoxazol-3-yl)benzenesulfonamide; 4-amino-N-(5-methyl-1,2-oxazol-3-yl)benzenesulfonamide; N1-(5-methyl-3-isoxazolyl)sulfanilamide;C10H11N3O3S.

A commercially available reagent of suitable grade.

Description. A white or yellowish white, crystalline powder.

Solubility. Very slightly soluble in water; soluble in 50 parts of ethanol (~750 g/l) TS and in 3 parts of acetone R.

Sulfamethoxazole RS

International Chemical Reference Substance.

Sulfamethoxypyridazine RS

International Chemical Reference Substance.

Sulfamic acid (5 g/l) TS

A solution of sulfamic acid R containing about 5 g of H3NO3S per litre.

Sulfamic acid (50 g/l) TS

A solution of sulfamic acid R containing about 50 g of H3NO3S per litre.

Note:Sulfamic acid (50 g/l) TS must be freshly prepared.

Sulfamic acid (80 g/l) TS

A solution of sulfamic acid R containing about 80 g of H3NO3S per litre.

Note:Sulfamic acid (80 g/l) TS must be freshly prepared.

Sulfamic acid R

H3NO3S.

Description.Colourless or white crystals.

Solubility.Soluble in water; slightly soluble in ethanol (~750 g/l) TS.

4-Sulfamoylbenzoic acid R

p-Sulfamoylbenzoic acid; C7H7NO4S.

Melting point. About 291 °C.

Sulfanilamide RS

International Chemical Reference Substance.

Sulfanilic acid R

C6H7NO3S (SRIP, 1963, p. 201).

Sulfanilic acid, diazotized, TS

Procedure.Dissolve 0.2 g of sulfanilic acid R in 20 ml of hydrochloric acid (1 mol/l) VS with warming, cool in ice, add drop by drop and with continuous stirring 2.5ml of sodium nitrite (35 g/l) TS, allow to stand in ice for 10 minutes and then add 1 ml of sulfamic acid (50 g/l) TS.

Sulfasalazine RS

International Chemical Reference Substance.

Sulfosalicylic acid (175 g/l) TS

A solution of sulfosalicylic acid R containing about 175 g/l of C7H6O6S.

Sulfosalicylic acid R

C7H6O6S,2H2O.

Description.White or slightly pink coloured, needle-like crystals.

Solubility.Soluble in water and ethanol (~750 g/l) TS.

Insoluble matter.Dissolve 5.0 g in 50 ml of water, heat to boiling and digest in a covered beaker on a water-bath for 1 hour. Filter through a tared filtering crucible,wash thoroughly and dry at 105 °C. The weight of the residue does not exceed 1.0 mg.

Sulfated ash.Gently ignite 1.0 g in a tared crucible or dish, other than platinum, until charred. Cool, moisten the residue with 1 ml of sulfuric acid (~1760 g/l) TSand ignite again; not more than 1.0 mg/g.

Sulfur dioxide R

SO2 (SRIP, 1963, p. 202).

Sulfuric acid (~10 g/l) TS

Procedure.Mix 100 ml of sulfuric acid (~100 g/l) TS with sufficient water to produce 1000 ml.

Sulfuric acid (~100 g/l) TS

Procedure.Add 57 ml of sulfuric acid (~1760 g/l) TS to sufficient water to produce 1000 ml (approximately 1 mol/l); d~1.065.

Sulfuric acid (~1125 g/l) TS

Sulfuric acid (~1760 g/l) TS, diluted with water to contain about 1125 g of H2SO4 per litre; d~1.61.

Sulfuric acid (~1760 g/l) TS

[sulfuric acid R] (SRIP, 1963, p. 202); d ~ 1.84.

Sulfuric acid (~1760 g/l), nitrogen-free, TS

Sulfuric acid (~1760 g/l) TS containing not less than 1760 g/l of H2SO4 and complying with the test for nitrates.

Nitrates.Mix 45 ml with 5 ml of water, cool and add 8 mg of diphenylbenzidine R; the solution is colourless or not more than very pale blue.

Sulfuric acid (~190 g/l) TS

Procedure.Mix 1 volume of sulfuric acid (~1760 g/l) TS with 9 volumes of water and cool. The resulting solution contains about 190 g/l of H2SO4; d~1.12.

Sulfuric acid (~440 g/l) TS

Procedure.Dilute 485 ml of sulfuric acid (~1760 g/l) TS to 1000 ml with water (~4.5 mol/l); d~1.25.

Sulfuric acid (~50 g/l) TS.

Procedure.To 50 ml of sulfuric acid (~100 g/l) TS add about 50 ml of water and mix.

Sulfuric acid (~570 g/l) TS

Procedure.Slowly add 3 volumes of sulfuric acid (~1760 g/l) TS to 7 volumes of water while gently stirring and cool; d~1.33.

Sulfuric acid (~635 g/l) TS

Sulfuric acid (~1760 g/l) TS, diluted with water to contain about 635 g of H2SO4 per litre; d~1.36.

Sulfuric acid (~700 g/l) TS

Procedure.Slowly add sulfuric acid (~1760 g/l) TS to an equal weight of water while gently stirring and cool; d~1.40.

Sulfuric acid (0.005 mol/l) VS

Sulfuric acid (~1760 g/l) TS, diluted with water to contain 0.4904 g of H2SO4 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sulfuric acid (0.5 mol/l) VS.

Sulfuric acid (0.01 mol/l) VS

Sulfuric acid (~1760 g/l) TS, diluted with water to contain 0.9808 g of H2SO4 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sulfuric acid (0.5 mol/l) VS.

Sulfuric acid (0.05 mol/l) VS

Sulfuric acid (~1760 g/l) TS, diluted with water to contain 4.904 g of H2SO4 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sulfuric acid (0.5 mol/l) VS.

Sulfuric acid (0.1 mol/l) VS

Sulfuric acid (~1760 g/l) TS, diluted with water to contain 9.808 g of H2SO4 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sulfuric acid (0.5 mol/l) VS.

Sulfuric acid (0.125 mol/l) VS.

Sulfuric acid (~1760 g/l) TS, diluted with water to contain 12.52 g of H2SO4 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sulfuric acid (0.5 mol/l) VS.

Sulfuric acid (0.25 mol/l) VS

Sulfuric acid (~1760 g/l) TS, diluted with water to contain 24.52 g of H2SO4 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the solution following the method described under sulfuric acid (0.5 mol/l) VS.

Sulfuric acid (0.5 mol/l) VS

Sulfuric acid (~1760 g/l) TS, diluted with water to contain 49.04 g of H2SO4 in 1000 ml.

Method of standardization.Ascertain the exact concentration of the 0.5 mol/l solution in the following manner: Dissolve about 1.5 g, accurately weighed, of anhydrous sodiumcarbonate R, previously dried at 270 °C for 1 hour, in 50 ml of water and titrate with the sulfuric acid solution, using methyl orange/ethanol TS asindicator. Each 52.99 mg of anhydrous sodium carbonate is equivalent to 1 ml of sulfuric acid (0.5 mol/l) VS.

Sulfuric acid/ethanol (~0.05 mol/l)

Carefully add 4.9 g of sulfuric acid (~1760 g/l) TS to about 800 ml ethanol (~750 g/l) TS, while mixing gently, and dilute to 1000 ml with ethanol (~750g/l) TS.

Sulfuric acid/ethanol TS

Procedure.Cool separately 10 ml of ethanol (~750 g/l) TS and 90 ml of sulfuric acid (~1760 g/l) TS to about -5 °C. Carefully add the acid to the ethanol, keeping thesolution as cool as possible, and mix gently.

Sulfuric acid/methanol TS

Procedure.Cool separately 10 ml of sulfuric acid (~1760 g/l) TS and 90 ml of methanol R. Carefully add the acid to the methanol, keeping the solution as cool aspossible and mix gently.

Sulfurous acid TS

[sulfurous acid R] (SRIP, 1963, p. 204).

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