Zie voor de gehalteberekening uit titraties Titratieberekeningen
Voorbeelden van titraties met cerium(IV)
Menadione (EP 1999) )
Assay
Dissolve 0.150 g in 15 ml of glacial acetic acid R in a flask with a stopper fitted with a valve.
Add 15 ml of dilute hydrochloric acid R and 1 g of zinc powder R. Close the flask. Allow the mixture to stand for 60 min, protected from light, with occasional shaking.
Filter the solution over a cotton wad, wash with three quantities, each of 10 ml, of carbon dioxide-free water R. Add 0.1 ml of ferroin R and immediately titrate the combined filtrate and washings with 0.1 M ammonium and cerium nitrate.
1 ml of 0.1 M ammonium and cerium nitrate is equivalent to 8.61 mg of C11H8O2.
Ascorbic Acid Tablets (BP 1998)
Assay
TEST
Weigh and powder 20 tablets.
Dissolve a quantity of the powder containing 0.15 g of Ascorbic Acid as completely as possible in a mixture of 30 ml of water and 20 ml of 1M sulphuric acid and titrate with 0.1M ammonium cerium( IV) sulphate VS using ferroin solution as indicator.
Each ml of 0.1M ammonium cerium( IV) sulphate VS is equivalent to 8.806 mg of C6H8O6.
Voorbeelden van titraties met jodaat
Alcoholic Iodine Solution (BP 1998)
Definition Alcoholic Iodine Solution is a cutaneous solution.
Iodine (25g)
Potassium Iodide (25g)
Purified Water (25ml)
Ethanol (90 per cent) (sufficient to produce 1000ml)
Assay for iodine
Dilute 10 ml with 20 ml of water and titrate with 0.1M sodium thiosulphate VS .
Each ml of 0.1M sodium thiosulphate VS is equivalent to 12.69 mg of I.
Assay for potassium iodide
To 10 ml add 30 ml of water and 50 ml of hydrochloric acid and titrate with 0.05M potassium iodate VS until the dark brown solution which is produced becomes pale brown.
Add 1 ml of amaranth solution and continue the titration until the red colour just changes to pale yellow.
From the number of ml of 0.05M potassium iodate VS required subtract half the number of ml of 0.1M sodium thiosulphate VS required in the Assay for iodine.
Each ml of the remainder is equivalent to 16.60 mg of KI.
Sodium Amidotrizoate Injection (BP 1998)
Assay
Mix a quantity containing 0.7 g of Sodium Amidotrizoate with 12 ml of 5M sodium hydroxide and 20 ml of water , add 1 g of zinc powder and boil under a reflux condenser for 30 minutes.
Cool, rinse the condenser with 30 ml of water , filter through absorbent cotton and wash the flask and the filter with two 20-ml quantities of water .
To the combined filtrate and washings add 80 ml of hydrochloric acid , cool and titrate with 0.05M potassium iodate VS until the dark brown solution becomes light brown.
Add 5 ml of chloroform and continue the titration, shaking well after each addition, until the chloroform becomes colourless. 1
Each ml of 0.05M potassium iodate VS is equivalent to 21.20 mg of C11H8I3N2 NaO4.
Determine the weight per ml of the injection, Appendix V G , and calculate the percentage w/v of sodium amidotrizoate, C11H8I3N2 NaO4.
Voorbeelden van titraties met kaliumbromaat
Benzyl Hydroxybenzoate (BP 1998)
Assay Gently boil 0.12 g under a reflux condenser with 20 ml of 2M sodium hydroxide for 30 minutes. Cool and extract with three 20-ml quantities of 1,2-dichloroethane . Wash the combined extracts with 20 ml of 0.1M sodium hydroxide and add the washings to the main aqueous phase, discarding the organic layer. To the aqueous solution add 25 ml of 0.0333M potassium bromate VS , 5 ml of a 12.5% w/v solution of potassium bromide and 10 ml of hydrochloric acid and immediately stopper the flask. Shake for 15 minutes and allow to stand for 15 minutes. Add 25 ml of dilute potassium iodide solution and shake vigorously. Titrate the liberated iodine with 0.1M sodium thiosulphate VS using starch mucilage , added towards the end of the titration, as indicator. Repeat the operation without the substance being examined. The difference between the titrations represents the amount of potassium bromate required. The volume of 0.0333M potassium bromate VS used is equivalent to half of the volume of 0.1M sodium thiosulphate VS required for the titration. Each ml of 0.0333M potassium bromate VS is equivalent to 7.608 mg of
C14H12O3. 
Titraties met perjodaat
Glycerol (EP 1999)
Assay
Thoroughly mix 0.1000 g with 45 ml of water R.
Add 25.0 ml of a 21.4 g/l solution of sodium periodate R.
Allow to stand protected from light for 15 min.
Add 5.0 ml of a 500 g/l solution of ethylene glycol R and allow to stand protected from light for 20 min.
Using 0.5 ml of phenolphthalein solution R as indicator, titrate with 0.1 M sodium hydroxide. Carry out a blank titration.
1 ml of 0.1 M sodium hydroxide is equivalent to 9.21 mg of C3H8O3.
Sorbitol
Reducing sugars.
Dissolve 5.0 g in 3 ml of water R with the aid of gentle heat.
Cool and add 20 ml of cupri-citric solution R and a few glass beads.
Heat so that boiling begins after 4 min and maintain boiling for 3 min.
Cool rapidly and add 100 ml of a 2.4 per cent V/V solution of glacial acetic acid R and 20.0 ml of 0.025 M iodine.
With continuous shaking, add 25 ml of a mixture of 6 volumes of hydrochloric acid R and 94 volumes of water R and, when the precipitate has dissolved, titrate the excess of iodine with 0.05 M sodium thiosulphate using 1 ml of starch solution R as indicator, added towards the end of the titration.
Not less than 12.8 ml of 0.05 M sodium thiosulphate is required.
Assay
Dissolve 0.400 g in water R and dilute to 100.0 ml with the same solvent.
To 10.0 ml of the solution add 20.0 ml of a 21.4 g/l solution of sodium periodate R and 2 ml of dilutesulphuric acid R and heat on a water-bath for exactly 15 min.
Cool and add 3 g of sodium hydrogen carbonate R a little at a time and 25.0 ml of 0.1 M sodium arsenite. Mix.
Add 5 ml of a 200 g/l solution of potassium iodide R and allow to stand for 15 min.
Titrate with 0.05 M iodine until the first trace of yellow colour appears.
Carry out a blank titration.
1 ml of 0.05 M iodine is equivalent to 1.822 mg of C6H14O6.
Voorbeelden van titraties met zilvernitraat
Iopanoic acid (EP 1999)
Assay
To 0.150 g in a 250 ml round-bottomed flask add 5 ml of strong sodium hydroxide solution R, 20 ml of water R, 1 g of zinc powder R and a few glass beads. Boil under a reflux condenser for 60 min. Allow to cool and rinse the condenser with 20 ml of water R, adding the rinsings to the flask. Filter through a sintered-glass filter and wash the filter with several quantities of water R. Collect the filtrate and washings. Add 40 ml of dilute sulphuric acid R and titrate immediately with 0.1 M silver nitrate. Determine the end-point potentiometrically (2.2.20), using a suitable electrode system such as silver-mercurous sulphate.
1 ml of 0.1 M silver nitrate is equivalent to 19.03 mg C11H12I3NO2.
Voorbeelden van titraties met EDTA
Compound Magnesium Trisilicate Tablets (BP 1998)
Definition Compound Magnesium Trisilicate Tablets contain, in each, 250 mg of Magnesium Trisilicate and 120 mg of Dried Aluminium Hydroxide. They have a peppermint flavour.
Assay for aluminium
Weigh and powder 20 tablets.
To a quantity of the powder equivalent to two tablets add 7 ml of hydrochloric acid and 7 ml of water , stir and heat on a water bath for 15 minutes, stirring occasionally.
Add 30 ml of hot water , mix and filter whilst hot, washing the filter well with hot water .
Cool the combined filtrate and washings and dilute to 100 ml with water .
Reserve 25 ml for the Assay for magnesium.
To 30 ml add 70 ml of water and 40 ml of 0.05M disodium edetate VS .
Add 0.2 ml of methyl red solution , neutralise to the orange colour of the indicator with 1M sodium hydroxide and heat on a water bath for 30 minutes.
Cool, add 3 g of hexamine and titrate the excess of disodium edetate with 0.05M lead nitrate VS using xylenol orange solution as indicator.
Each ml of 0.05M disodium edetate VS is equivalent to 1.349 mg of Al.
Assay for magnesium
To 25 ml of the solution reserved in the Assay for aluminium add 1 g of ammonium chloride and 10 ml, or a quantity sufficient to redissolve the precipitate that is produced, of triethanolamine .
Add 150 ml of water and 5 ml of ammonia buffer pH 10.9 and titrate immediately with 0.05M disodium edetate VS using mordant black 11 solution as indicator.
Each ml of 0.05M disodium edetate VS is equivalent to 1.215 mg of Mg.
Compound Aluminium Paste (BP 1998)
Extemporaneous preparation The following formula and directions apply.
Aluminium Powder 200 g
Zinc Oxide 400 g
Liquid Paraffin 400 g
Assay for aluminium
Disperse 1 g in a mixture of 20 ml of hydrochloric acid and 20 ml of water with the aid of gentle heat, filter, wash the filter with water , cool the combined filtrate and washings and dilute to 100 ml with water (solution A).
Neutralise 10 ml of solution A to congo red paper with 5M sodium hydroxide , add 50 ml of 0.05M disodium edetate VS , heat on a water bath for 30 minutes, cool, add 3 g of hexamine and titrate the excess of disodium edetate with 0.05M lead nitrate VS , using xylenol orange solution as indicator, to a purplish red colour.
Add 1 g of sodium fluoride to the resulting solution, heat on a water bath for 15 minutes, cool and continue the titration to a purplish red colour.
The volume of 0.05M lead nitrate VS used in the second titration represents the amount of disodium edetate liberated from the complex. Each ml of 0.05M disodium edetate VS is equivalent to 1.349 mg of Al.
Assay for zinc oxide
The difference between the volume of 0.05M disodium edetate VS added in the Assay for aluminium and the total volume of 0.05M lead nitrate VS used represents the amount of zinc present. Each ml of 0.05M disodium edetate VS is equivalent to 4.068 mg of ZnO.
Amfimetrische titraties
Lidocaine Gel (BP 1998)
Assay
Disperse a quantity containing the equivalent of 10 mg of anhydrous lidocaine hydrochloride in 20 ml of water .
Add 5 ml of acetate buffer pH 2.8 , 120 ml of chloroform and 5 ml of dimethyl yellow oracet blue B solution and titrate with 0.005M dioctyl sodium sulphosuccinate VS , swirling vigorously. Near the end point add the titrant dropwise and, after each addition, swirl vigorously, allow to separate and swirl gently for 5 seconds.
The end point is indicated when the colour of the chloroform layer changes from green to pinkish grey.
Repeat the operation without the preparation being examined.
The difference between the titrations represents the amount of dioctyl sodium sulphosuccinate required.
Each ml of 0.005M dioctyl sodium sulphosuccinate VS is equivalent to 1.354 mg of C14H22N2O,HCl.
Determine the weight per ml of the gel, Appendix V G , and calculate the percentage of C14H22N2O,HCl, weight in volume.
Co-codaprin Tablets (BP 1998)
Definition Co-codaprin Tablets contain Codeine Phosphate and Aspirin in the proportions, by weight, 1 part to 50 parts.
Assay
Weigh and powder 20 tablets.
For codeine phosphate
To a quantity of the powder containing 24 mg of Codeine Phosphate add 5 ml of 5M sodium hydroxide and 15 ml of water , shake for 2 minutes and extract with three 50-ml quantities of chloroform .
Wash each extract with the same 10 ml of water , filter through absorbent cotton previously moistened with chloroform and evaporate the combined extracts to about 60 ml on a water bath in a current of air.
Cool, add 25 ml of water , 5 ml of acetate buffer pH 2.8 and 5 ml of dimethyl yellow �oracet blue B solution and titrate with 0.01M dioctyl sodium sulphosuccinate VS with vigorous swirling until near the end point, then add the titrant dropwise and, after each addition, swirl vigorously, allow to separate and swirl gently for 5 seconds.
The end point is indicated by the appearance of a permanent pinkish grey colour in the chloroform layer.
Repeat the operation without the powdered tablets.
The difference between the titrations represents the amount of dioctyl sodium sulphosuccinate required.
Calculate the content of C18H21NO3,H3 PO4,�H2O using the result obtained by dissolving 40 mg of codeine phosphate BPCRS in 25 ml of water and 5 ml of acetate buffer pH 2.8 , adding 60 ml of chloroform and 5 ml of dimethyl yellow �oracet blue B solution, shaking well to dissolve the codeine phosphate and completing the method described above beginning at the words 'and titrate...'.
For aspirin
To a quantity of the powder containing 0.8 g of Aspirin add 20 ml of water and 2 g of sodium citrate and boil under a reflux condenser for 30 minutes.
Cool, wash the condenser with 30 ml of warm water and titrate with 0.5M sodium hydroxide VS using phenolphthalein solution R1 as indicator.
Each ml of 0.5M sodium hydroxide VS is equivalent to 45.04 mg of C9H8O4.
Cetostearyl Alcohol (Type A), Emulsifying (EP 1999)
Definition
Emulsifying cetostearyl alcohol (type A) is a mixture which contains not less than 80.0 per cent of cetostearyl alcohol and not less than 7.0 per cent of sodium cetostearyl sulphate, both calculated with reference to the anhydrous substance. A suitable buffer may be added.
Assay
Cetostearyl alcohol
Examine by gas chromatography (2.2.28).
Sodium cetostearyl sulphate
Disperse 0.300 g in 25 ml of methylene chloride R. Add 50 ml of water R and 10 ml of dimidium bromide-sulphan blue mixed solution R. Titrate with 0.004 M benzethonium chloride, using sonication and heating and allowing the layers to separate before each addition, until the colour of the lower layer changes from pink to grey.
1 ml of 0.004 M benzethonium chloride is equivalent to 1.434 mg of sodium cetostearyl sulphate.
Titraties met Titaan(III)
Paediatric Ferrous Sulphate Oral Solution (BP 1998)
Extemporaneous preparation The following formula and directions apply.
Ferrous Sulphate (12g)
Ascorbic Acid (2g)
Orange Syrup (100ml)
Double-strength Chloroform Water (500ml)
Water sufficient to produce (1000ml)
Assay
To 20 ml add 45 ml of water , 0.2 ml of hydrochloric acid and dilute potassium permanganate solution dropwise until a permanent pink colour is produced.
Add 10 ml of hydrochloric acid and 3 ml of a 10% w/v solution of ammonium thiocyanate and titrate with 0.1M titanium ( III) chloride VS maintaining a steady flow of carbon dioxide through the flask.
Each ml of 0.1M titanium ( III) chloride VS is equivalent to 27.80 mg of FeSO4,7H2O.
Ephedrine (EP 1999)
Assay
Dissolve 0.200 g in 5 ml of alcohol R and add 20.0 ml of 0.1M hydrochloric acid . Using 0.05 ml of methyl red solution R as indicator, titrate with 0.1M sodium hydroxide until a yellow colour is obtained.
1 ml of 0.1M hydrochloric acid is equivalent to 16.52 mg of C10H15NO.
Ephedrine Hydrochloride (EP 1999)
Assay
Dissolve 0.170 g in 10 ml of mercuric acetate solution R, warming gently. Add 50 ml of acetone R and 1 ml of a saturated solution of methyl orange R in acetone R. Titrate with 0.1M perchloric acid until a red colour is obtained.
1 ml of 0.1M perchloric acid is equivalent to 20.17 mg of C10H16ClNO.
Racephedrine Hydrochloride (EP 1999)
Assay
Dissolve 0.170 g in 30 ml of alcohol R. Add 5.0 ml of 0.01M hydrochloric acid . Carry out a potentiometric titration (2.2.20 ), using 0.1M sodium hydroxide . Read the volume added between the two points of inflexion.
1 ml of 0.1M sodium hydroxide corresponds to 20.17 mg of C10H16ClNO.
Ephedrini Hydrochloridum (Ned. Pharm. Ed VI)
Gehalte: Los op ongeveer 250 mg, nauwkeurig gewogen, in 10 ml water en titreer, na toevoegen van kaliumchromaat, met zilvernitraat.
1 ml 0,1000 N. zilvernitraat = 20.15 mg C10H15ON.HCl
Physostigmine salicylate (EP 1999)
Assay Dissolve 0.350 g in 50 ml of a mixture of equal volumes of anhydrous acetic acid R and chloroform R. Titrate with 0.1 M perchloric acid determining the end-point potentiometrically (2.2.20). 1 ml of 0.1 M perchloric acid is equivalent to 41.35 mg of C22H 27N3O5.
Sodium Salicylate (EP 1999)
Assay Dissolve 0.130 g in 30 ml of anhydrous acetic acid R. Titrate with 0.1 M perchloric acid, determining the end-point potentiometrically (2.2.20). 1 ml of 0.1 M perchloric acid is equivalent to 16.01 mg of C7H5NaO3.
Quinine Sulphate (EP 1999)
(C20H24N2O 2)2,H2SO4,2H 2O 783.0
Assay
Dissolve 0.3000 g in a mixture of 10 ml of chloroform R and 20 ml of acetic anhydride R. Titrate with 0.1M perchloric acid , determining the end-point potentiometrically (2.2.20 ).
1 ml of 0.1M perchloric acid is equivalent to 24.90 mg of C40H50N4O8 S.
Quinine Hydrochloride (EP 1999)
C20H24N2O2 ,HCl,2H2O 396.9
Assay
Dissolve 0.3000 g in a mixture of 50 ml of anhydrous acetic acid R and 20 ml of acetic anhydride R and add 5 ml of mercuric acetate solution R. Titrate with 0.1M perchloric acid , determining the end-point potentiometrically (2.2.20 ).
1 ml of 0.1M perchloric acid is equivalent to 18.04 mg of C20H25ClN2O2 .
Quinine Dihydrochloride (BP 1998)
C20H24N2O2 ,2HCl 397.3
Assay
Dissolve 0.3 g in a mixture of 50 ml of anhydrous acetic acid and 20 ml of acetic anhydride , add 10 ml of mercury ( II) acetate solution and carry out method I for non-aqueous titration, Appendix VIII A , using crystal violet solution as indicator. Each ml of 0.1M perchloric acid VS is equivalent to 19.87 mg of C20H24N2O2 ,2HCl.
Quinine Bisulphate (BP 1998)
C20H24N2O2 ,H2SO4,7H2O 548.6
Assay Dissolve 0.45 g in 15 ml of water . Add 25 ml of 0.1M sodium hydroxide VS and extract with three 25-ml quantities of chloroform . Wash the combined chloroform extracts with 20 ml of water , combine the aqueous solutions and reserve for the test for Titratable cation. Dry the chloroform extracts with anhydrous sodium sulphate , evaporate to dryness at a pressure of 2 kPa and dissolve the residue in 50 ml of anhydrous acetic acid . Carry out method I for non-aqueous titration, Appendix VIII A , using crystal violet solution as indicator. Each ml of 0.1M perchloric acid VS is equivalent to 21.13 mg of C20H24N2O 2,H2SO4.
Codeine Hydrochloride
Assay
Dissolve 0.3 g in a mixture of 10 ml of anhydrous acetic acid and 20 ml of 1,4-dioxan . Carry out Method I for non-aqueous titration, Appendix VIII A , using 7 ml of mercury(<-- II>) acetate solution and determining the end point potentiometrically. Each ml of 0.1M perchloric acid VS is equivalent to 33.58 mg of C18H21NO3,HCl.
Codeine Phosphate
Assay
Dissolve 0.350 g in a mixture of 10 ml of anhydrous acetic acid R and 20 ml of dioxan R. Titrate with 0.1M perchloric acid using 0.05 ml of crystal violet solution R as indicator.
1 ml of 0.1M perchloric acid is equivalent to 39.74 mg of C18H24NO7P.
Codeine Phosphate hemihydrate (EP 1999)
Assay
Dissolve 0.350 g in a mixture of 10 ml of anhydrous acetic acid R and 20 ml of dioxan R. Titrate with 0.1 M perchloric acid using 0.05 ml of crystal violet solution R as indicator.
1 ml of 0.1 M perchloric acid is equivalent to 39.74 mg of C18H24NO7P.
Codeini Phosphas (Ned. Pharm. Ed VI)
Mol.Gwew. 424,1 (C18H21O3N.H3PO4. 1
� H2O)Gehalte: Droog ongeveer 500 mg, nauwkeurig gewogen. Bepaal het gewichtsverlies en bereken hieruit het watergehalte. Los het gedroogde poeder op in een mengsel van 8 ml neutrale spiritus en 2 ml water, voeg toe 10 ml chloroform en titreer het mengsel na toevoegen van fenolftaleine met alkali.
1 ml 0,1000 N. alkali = 19,85 ml C18H21O3N.H3PO4.
Papaverine Hydrochloride (BP 1998)
Assay Dissolve 0.300 g in 30 ml of anhydrous acetic acid R and add 6 ml of mercuric acetate solution R. Titrate with 0.1 M perchloric acid using 0.05 ml of crystal violet solution R as indicator. 1 ml of 0.1 M perchloric acid is equivalent to 37.59 mg of C20H22ClNO4.
Diprophylline (EP 1999)
Assay
In order to avoid overheating in the reaction medium, mix thoroughly throughout and stop the titration immediately after the end-point has been reached.
Dissolve 0.200 g in 3.0 ml of anhydrous formic acid R and add 50.0 ml of acetic anhydride R. Titrate with 0.1 M per-chloric acid, determining the end-point potentiometrically (2.2.20).
1 ml of 0.1 M perchloric acid is equivalent to 25.42 mg of C10H14N4O4.
Flunitrazepamum (EP 1999)
pKa 1,8 Assay Dissolve 0.250 g in 20 ml of anhydrous acetic acid R and add 50 ml of acetic anhydride R. Titrate with 0.1 M perchloric acid, determining the end-point potentiometrically (2.2.20). 1 ml of 0.1 M perchloric acid is equivalent to 31.33 mg of C16H12FN3O3.
Pentobarbital sodium (EP 1999)
Free pentobarbital.
Not more than 3.5 per cent. Dissolve 2.00 g in 75 ml of dimethylformamide R, heating gently if necessary. Add 0.25 ml of a 10 g/l solution of thymol blue R in dimethylformamide R. Titrate with 0.1 M sodium methoxide until the colour changes from olive-green to blue. Carry out a blank titration.
1 ml of 0.1 M sodium methoxide is equivalent to 22.63 mg of pentobarbital.
Assay
Dissolve 0.200 g in 15 ml of a 127.5 g/l solution of silver nitrate R in pyridine R. Titrate with 0.1 M ethanolic sodium hydroxide until a pure blue colour is obtained, using 0.5 ml of thymolphthalein solution R as indicator. Carry out a blank titration.
1 ml of 0.1 M ethanolic sodium hydroxide is equivalent to 24.83 mg of C11H17N2NaO3.
Lorazepamum (EP 1999)
pKa 1,3 en 11,5
C15H10Cl2N2O2 Mr 321.2
Assay
Dissolve 0.250 g in 30 ml of dimethylformamide R. Titrate with 0.1 M tetrabutylammonium hydroxide, determining the end-point potentiometrically (2.2.20). Protect the solution from atmospheric carbon dioxide throughout the titration.
1 ml of 0.1 M tetrabutylammonium hydroxide is equivalent to 32.12 mg of C15H10Cl2N2O2.
23 december 1999
Staf Farmaceutische Analyse 5e-jaar