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Theme: Analysis of quality of drugs showing oxidation-reduction properties

June 21, 2024

Theme: Analysis of pharmaceutical preparations showing redox properties.

Browse: British Pharmacopoeia 2009 SP IX

British Pharmacopoeia Volume I & II

Monographs: Medicinal and Pharmaceutical Substances

Oxygen

Oxygen

General Notices

(Ph Eur monograph 0417)

Oxygenum

O₂

ээ32.00ээ7782-44-7

Oxygen should be kept in approved metal cylinders, the shoulders of which are painted white

and the remainder black. The cylinder should carry a label stating ‘Oxygen’. In addition,

‘Oxygen’ or the symbol ‘O2‘ should be stencilled in paint on the shoulder of the cylinder.

When Oxygen is intended for use in a room in which magnetic resonance imaging (MRI) is

being performed, the cylinder and fittings should be made from suitable non-ferromagnetic

materials and labelled accordingly.

Ph Eur

DEFINITION

Content

Minimum 99.5 per cent V/V of O2.

This monograph applies to oxygen for medicinal use.

CHARACTERS

Appearance

Colourless, odourless gas.

Solubility

At 20 °C and at a pressure of 101 kPa, 1 volume dissolves in about 32 volumes of water.

PRODUCTION

Carbon dioxide

Maximum 300 ppm V/V, determined using an infrared analyser (2.5.24).

Gas to be examinedэThe substance to be examined. It must be filtered to avoid stray light

phenomena.

Reference gas (a)эOxygen R.

Reference gas (b)эMixture containing 300 ppm V/V of carbon dioxide R1 in nitrogen R1.

Calibrate the apparatus and set the sensitivity using reference gases (a) and (b). Measure the

content of carbon dioxide in the gas to be examined.

Carbon monoxide

Maximum 5 ppm V/V, determined using an infrared analyser (2.5.25).

Gas to be examinedэThe substance to be examined. It must be filtered to avoid stray light

phenomena.

Reference gas (a)эOxygen R.

Reference gas (b)эMixture containing 5 ppm V/V of carbon monoxide R in nitrogen R1.

Calibrate the apparatus and set the sensitivity using reference gases (a) and (b). Measure the

content of carbon monoxide in the gas to be examined.

Water (2.5.28)

Maximum 67 ppm V/V.

Obtaining

Distillation of liquefied (condensed) air. Now oxygen to receive from air by its liquefaction. Air contains 21 % of oxygen О₂ and 79 % of nitrogen N₂. At distillation of liquefied (condensed) air, at first is distillate of nitrogen (-195,8 °С), and then – oxygen (-183 °С).
Electrolysis of water.

Cathode: 2Н₂О + 2е® 2ОН^– + Н₂

Anode: 2Н₂О – 4е ® 4Н⁺ + О₂

Laboratoric metods (for obtaining no more quatitative O₂):

а) Thermal decomposition of potassium chlorate:

2KClO₃ →2KCl + 3O₂

b) Thermal decomposition of mercury(II) oxide:

2HgO → 2Hg + O₂

c) Interaction peroxides with CO₂:

2Na₂O₂ + 2CO₂ ® 2Na₂CO₃ + O₂

IDENTIFICATION

First identificationэC.

Second identificationэA, B.

эA. Place a glowing splinter of wood in the substance to be examined. The splinter bursts into flame.

эB. Shake with alkaline pyrogallol solution R. The substance to be examined is absorbed and the solution becomes dark brown.

эC. It complies with the limits of the assay.

Other reaction:

(SPU) Colouring in the brown colour of a mix of nitrogen(II) oxide and oxygen:

2NO + O₂ = 2NO₂

brown gas

(Difference from nitrogen (I) oxide).

TESTS

Carbon dioxide (2.1.6) –inadmissible impurity.

Maximum 300 ppm V/V, determined using a carbon dioxide detector tube.

Or by means reaction: Ba(OH)₂ + CO₂ = BaCO₃¯ + H₂O

opalescence is not be present

Carbon monoxide (2.1.6) –inadmissible impurity.

Maximum 5 ppm V/V, determined using a carbon monoxide detector tube.

Or by means reaction: СО + 2[Ag(NH₃)₂]NO₃ + 2H₂O = 2Ag¯ + (NH₄)₂CO₃ + 2NH₄NO₃

brown colour is not be present

Water vapour (2.1.6)

Maximum 67 ppm V/V, determined using a water vapour detector tube.

IMPURITIES

Specified impuritiesэA, B, C.

эA. carbon dioxide,

эB. carbon monoxide,

эC. water.

Assay

Determine the concentration of oxygen using a paramagnetic analyser (2.5.27).

(Ph. Eur. method 2.5.27)

Oxygen in gases is determined using a paramagnetic analyser.

The principle of the method is based on the high paramagnetic sensitivity of the oxygen molecule. Oxygen exerts a strong interaction on magnetic fields, which is measured electronically, amplified and converted to a reading of oxygen concentration. The measurement of oxygen concentration is dependent upon the pressure and temperature and, if the analyser is not automatically compensated for variations in temperature and pressure, it must be calibrated immediately prior to use. As the paramagnetic effect of oxygen is linear the instrument must have a suitable range with a readability of 0.1 per cent or better.

Calibration of the instrument Make the setting in the following manner:

—set the zero by passing nitrogen R1 through the instrument at a suitable flow rate until a constant reading is obtained. It should be set to zero according to the manufacturer’s instructions;

—set the appropriate limit by passing air (20.9 per cent V/V O₂) through the instrument at a suitable flow rate until a constant reading is obtained. The limit should be set to 20.9 per cent V/V in accordance with the manufacturer’s instructions.

Assay Pass the gas to be examined through the instrument at a constant flow rate until a suitable reading is obtained.

STORAGE

As a compressed gas or liquid in appropriate containers, complying with the legal regulations.

Taps and valves are not to be greased or oiled.

Action and use

Apply at the diseases, accompanied hypoxia (oxygen depletion). In particular, at poisonings of СО, HCN, Cl₂, phosgene COCl₂ and other gases use a mix with air, containing 40-60 % of oxygen.

Use an oxygen cocktail (oxygen foam) for glaucoma treatment, and also for improvement of exchange processes.

Widely use oxygen for so-called hyperbaric oxygenation – oxygen application under the raised pressure (1,2 – 2 atm), in surgery (operation in special pressure chamber), intensive therapy of heavy diseases, in reanimotologia. Thus saturation of tissues by oxygen, the brain is protected from hypoxia.

Carbogenum – is the gas mix, containing 95 % О₂ and 5–7% СО₂, applied in anesthesiology for respiration stimulation.

Browse: British Pharmacopoeia 2009 SP IX

British Pharmacopoeia Volume I & II

Monographs: Medicinal and Pharmaceutical Substances

Chlorinated Lime

Chlorinated Lime

General Notices

Calcaria chlorata

Calcii hypochloris crudus

Calcium hypochlorosum

Possible structure of Chlorinated Lime is:

Chlorinated Lime is a mix of Ca(ClО)₂ and CaCl₂:

Ca(ClО)₂×CaCl₂ = Ca₂O₂Cl₄ = 2CaOCl₂

Elementary formula Chlorinated Lime is: CaOCl₂

OBTAINING

Heating (t » 1000° C) Calcium natural minerals with the next saturation of chlorine (Cl₂).

CaCO₃ ® CaО + CO₂;

CaО + H₂O = Ca(OH)₂ + Q;

Ca(OH)₂ + Cl₂ = CaOCl₂ + H₂O

DEFINITION

Chlorinated Lime contains not less than 30.0% w/w of available chlorine, Cl.

CHARACTERISTICS

A dull white powder.

Partly soluble in water and in ethanol (96%).

IDENTIFICATION

э A. (BrPh, SP IX). Interaction with mineral acids. Evolves chlorine copiously on the addition of 2M hydrochloric acid .

CaOCl₂ + HCl = CaCl₂ + H₂O + Cl₂↑

эB. (BrPh, SP IX). When shaken with water and filtered, the filtrate yields reaction C characteristic of calcium salts and reaction A characteristic of chlorides, Appendix VI.

Calcium and Calcium Salts

A. Reaction with glyoxal-hydroxyanil alcoholic solution in the alkaline medium.

To 0.2 ml of a neutral solution containing a quantity of the substance to be examined equivalent to about 0.2 mg of calcium (Ca²⁺) per millilitre or to 0.2 ml of the prescribed solution add 0.5 ml of a 2 g/l solution of glyoxal-hydroxyanil R in ethanol (96 per cent) R, 0.2 ml of dilute sodium hydroxide solution R and 0.2 ml of sodium carbonate solution R. Shake with 1 ml to 2 ml of chloroform R and add 1 ml to 2 ml of water R. The chloroform layer is coloured red.

B. Reaction with potassium ferrocyanide solution in the acetic-acid medium.

Dissolve about 20 mg of the substance to be examined or the prescribed quantity in 5 ml of acetic acid R. Add 0.5 ml of potassium ferrocyanide solution R. The solution remains clear. Add about 50 mg of ammonium chloride R. A white, crystalline precipitate is formed.

Ca²⁺+ К + 2NH₄⁺+ [Fe(CN)₆]^4–→(NH₄)₂КCa[Fe(CN)₆]↓.

white, crystalline precipitate

Chlorides

A. Reaction with silver nitrate solution in the nitric-acid medium.

Dissolve in 2 ml of water R a quantity of the substance to be examined equivalent to about 2 mg of chloride (Cl^–) or use 2 ml of the prescribed solution. Acidify with dilute nitric acid R and add 0.4 ml of silver nitrate solution R1. Shake and allow to stand. A curdled, white precipitate is formed. Centrifuge and wash the precipitate with three quantities, each of 1 ml, of water R. Carry out this operation rapidly in subdued light, disregarding the fact that the supernatant solution may not become perfectly clear. Suspend the precipitate in 2 ml of water R and add 1.5 ml of ammonia R. The precipitate dissolves easily with the possible exception of a few large particles which dissolve slowly.

Cl^– + Ag+ = AgCl↓

white

Other reaction of Ca²⁺:

1. SPU, N. Reaction with ammonium oxalate in the acetic-acid medium.

CaOCl₂ + 2СН₃СООН→ (СН₃СОО)₂Ca + Cl₂ + H₂O;

(СН₃СОО)₂Ca+ (NH₄)₂C₂O₄ → CaС₂O₄↓ + 2СН₃СООNH₄

Ca²⁺+ C₂O₄^2– → CaС₂O₄↓.

2. SPU, N. Pyrochemical reaction. Calcium salt, wetted of HCl Р and brought in colourless flame, paint its in orange-red colour.

Са²⁺ + hν → *Са²⁺→ Са²⁺+ hν₁.

ASSAY

(BrPh, SP IX). Iodometry, substitute titration.

Triturate 4 g with successive small quantities of water, dilute to 1000 ml with water and shake thoroughly. Mix 100 ml of the resulting suspension with a solution containing 3 g of potassium iodide in 100 ml of water, acidify with 5 ml of 6M acetic acid and titrate the liberated iodine with 0.1M sodium thiosulphate VS. Each ml of 0.1M sodium thiosulphate VS is equivalent to 3.545 mg of available chlorine, Cl.

Indicator – starch solution, add after change colour from brown to pale yellow and titrate to decoloration of test solution.

CaOCl₂ + 2HCl = CaCl₂ + Сl₂ + H₂O;

Cl₂ + 2KI = I₂ + 2KCl;

I₂ + 2Na₂S₂O₃ = 2NaI + Na₂S₄O₆.

CaOCl₂ + 2H⁺ + 2e ® CaCl₂ + H₂O

Е_m(Cl₂) = М. m./2

Cl₂ ≥ 32%

STORAGE

On exposure to air Chlorinated Lime becomes moist and gradually decomposes, carbon

dioxide being absorbed and chlorine evolved.

Action and use

Disinfectant.

Hydrogen peroxide solution (6 per cent)

Definition. Hydrogen peroxide solution (6 per cent) contains not less than 5.0% w/w and not more than 7% of H₂O₂ (34.01). It may contain a suitable stabilizing agent.

Characteristics. A clear, colourless liquid.

Identification. To 1 ml of sample add 2 ml of dilute H₂SO₄, and 2 ml of ether, and 0.2 ml of K₂Cr₂O₇ and shake. The phase of organic solvent is blue.

blue color (perchromate acid)

Acidity. Dilute 10 ml with 20 ml of water and add 0.25 ml of methyl red solution. Not less than 0.20 ml and not more than 1 ml of 0.1 M sodium hydroxide is required to change the color of the solution.

Organic stabilizers. Shake 20 ml with successive quantities of 10.5 and 5 ml of chloroform. Evaporate the combined chloroform extracts at a temperature not exceeding 25* at a pressure of 2kPa and dry in a desiccator. Any residue weighs not more than 5 mg.

Assay. Dilute 10 ml to 100 ml with water. To 10 ml of the resulting solution add 5 ml of 1M sulphuric acid and titrate with 0.1N potassium permanganate. Each ml of 0.02 M potassium permanganate is equivalent to 1.701 mg of H₂O₂ or 0.56 ml of oxygen.

Storage. Hydrogen peroxide solution should be protected from light. If the solution does not contain a stabilizing agent, it should be stored at a temperature not exceeding 15*. It should not be stored for long periods.

Action and use. Antiseptic; deodorant.

When hydrogen peroxide is prescribed or demanded, Hydrogen peroxide solution (6 per cent) shall be dispensed or supplied.

Browse: British Pharmacopoeia 2009 SPU, add.1

British Pharmacopoeia Volume I & II

Monographs: Medicinal and Pharmaceutical Substances

Hydrogen Peroxide Solution (3 per cent)

Hydrogen Peroxide Solution (3 per cent)

General Notices

H₂O₂

Dilute Hydrogen Peroxide Solution

(Ph Eur monograph 0395)

Hydrogenii peroxidum 3 per centum

Solutio Hydrogenii peroxydi diluta

Hydrogeniun peroxydatum

DEFINITION

Content

2.5 per cent m/m to 3.5 per cent m/m of H2O2 (Mr 34.01).

1 volume of hydrogen peroxide solution (3 per cent) corresponds to about 10 times its volume of oxygen. A suitable stabiliser may be added.

CHARACTERS

Appearance

Colourless, clear liquid.

OBTAINING

1. Interaction barium peroxide with acid (Tenar method, 1818):

ВаО₂ + H₂SO₄ ® ВаSO₄¯ + Н₂О₂

2. Electrolysis of 40–68% sulphuric acid H₂SO₄ (industrial method):

H₂SO₄ + Н₂О Û Н₃О⁺ + HSO₄^–

Cathode: 2Н₃О⁺ + 2е ® 2Н₂О + Н₂

Anode: 2HSO₄^– – 2e ® H₂S₂O₈ (peroxodisulphuric or persulphuric acid)

General reaction of electrolysis:

2H₂SO₄ H₂ + H₂S₂O₈

At the heating of solution to 70–75 °С in a vacuum the persulphuric acid decomposed with formation hydrogen peroxide H₂O₂ and sulphuric acid H₂SO₄:

H₂S₂O₈+ 2H₂O = H₂O₂ + 2H₂SO₄

Obtained dilute solution H₂O₂distil in a vacuum at 70 °С and obtain 30–60% solutions.

IDENTIFICATION

эA. (BrPh, SPU, add. 1). Reaction with potassium permanganate solution in the sulphate-acid medium. To 2 ml add 0.2 ml of dilute sulphuric acid R and 0.2 ml of 0.02 M potassium permanganate. The solution becomes colourless or slightly pink within 2 min.

5H₂O₂ + 2KMnO₄ + 3H₂SO₄ = 2MnSO₄ + K₂SO₄ + 5O₂ + 8H₂O

MnO₄^– + 8H⁺+ 5 e ® Mn²⁺ + 4H₂O 5 2

H₂O₂ – 2e ® O₂^o + 2H⁺ 2 5

5H₂O₂ + 2MnO₄^– + 6H⁺ ® 2Mn²⁺ + 5O₂ + 8H₂O

эB. (BrPh, SPU, add. 1). Reaction with potassium chromate (or dichromate – SPU) solution in the sulphate-acid medium and presence of ether. To 0.5 ml add 1 ml of dilute sulphuric acid R, 2 ml of ether R and 0.1 ml of potassium chromate solution R and shake. The ether layer is blue.

K₂Cr₂O₇ + H₂SO₄ = K₂SO₄ + H₂Cr₂O₇

When concentration of H₂O₂is small (diluted solution) is formed perchromic acid H₂Cr₂O₈:

H₂Cr₂O₇ + H₂O₂ = H₂Cr₂O₈ + H₂O

When solution of H₂O₂is more concentrated is formed perchromic acid H₂Cr₂O₁₂ or chrom peroxide CrO₅:

H₂Cr₂O₇ + 5H₂O₂ = H₂Cr₂O₁₂ + 5H₂O

H₂Cr₂O₇ + 4H₂O₂ = 2CrO₅ + 5H₂O

It is possible formation other perchromic acids: CrO₃×nH₂O (HСrO₅, H₃CrO₈, H₂CrO₆). Perchromic acids dissolves in ether and ether layer is blue. But blue colour quickly is pass into green colour, because there is reduction reaction Сr(VI) to Cr(III).

эC. It complies with the requirement for the content of H2O2. (see Tests – Organic stabilizers).

TESTS

Acidity

To 10 ml add 20 ml of water R and 0.25 ml of methyl red solution R. Not less than 0.05 ml

and not more than 1.0 ml of 0.1 M sodium hydroxide is required to change the colour of the indicator.

Organic stabilisers

Maximum 250 ppm.

Shake 20 ml with 10 ml of chloroform R and then with 2 quantities, each of 5 ml, of chloroform R. Evaporate the combined chloroform layers under reduced pressure at a temperature not exceeding 25 °C and dry in a desiccator. The residue weighs a maximum of 5 mg.

Non-volatile residue

Maximum 2 g/l.

Allow 10 ml to stand in a platinum dish until all effervescence has ceased. Evaporate to dryness on a water-bath and dry at 100-105 °C. The residue weighs a maximum of 20 mg.

ASSAY

(BrPh, SPU, add. 1). Permanganatometry, direct titration (nonindicator method). Dilute 10.0 g to 100.0 ml with water R. To 10.0 ml of this solution add 20 ml of dilute sulphuric acid R. Titrate with 0.02 M potassium permanganate until a pink colour is obtained.

1 ml of 0.02 M potassium permanganate is equivalent to 1.701 mg of H2O2 or 0.56 ml of oxygen.

5H₂O₂ + 2KMnO₄ + 3H₂SO₄ = 2MnSO₄ + K₂SO₄ + 5O₂ + 8H₂O

5H₂O₂ + 2MnО₄^– + 6H⁺ ® 2Mn²⁺ + 5O₂ + 8H₂O

E_m(H₂O₂)= М. m./2

Formula for calculation percentage yields of hydrogen peroxide in the drug:

V_т– volum of titrant KMnО₄, ml;

К_p– coefficient recalculation of standardized solution (titrant);

Т_{(KMnО4/Н2О2)} – volum of solution Н₂О₂, corresponded 1 ml of titrant;

V_volumetric_flask– volume of volumetric flask, in which diluted V ml of substance;

V_aliquot – volume of solution from volumetric flask, necessary for titration (volume of volumetric pipette).

STORAGE

Protected from light, and if the solution does not contain a stabiliser, at a temperature below 15 °C.

LABELLING

If the solution contains a stabiliser, the label states that the contents are stabilised. The competent authority may require that the name of the stabiliser be stated on the label.

CAUTION

It decomposes in contact with oxidisable organic matter and with certain metals and if allowed to become alkaline.

Ph Eur

Action and use

Antiseptic; deodorant.

When hydrogen peroxide is prescribed or demanded, Hydrogen Peroxide Solution (6 per cent) shall be dispensed or supplied.

Ph Eur

Browse: British Pharmacopoeia 2009 SPU, add. 1

British Pharmacopoeia Volume I & II

Monographs: Medicinal and Pharmaceutical Substances

Hydrogen Peroxide Solution (30 per cent)

Hydrogen Peroxide Solution (30 per cent)

General Notices

(Ph Eur monograph 0396)

H₂O₂

Hydrogenii peroxidum 30 per centum

Solutio Hydrogenii peroxydi concentrata

Hydrogeniun peroxydatum

Perhydrolum

Ээээ

34,01 7722-84-1

DEFINITION

Content

29.0 per cent m/m to 31.0 per cent m/m of H2O2 (Mr 34.01). 1 volume of hydrogen peroxyde solution (30 per cent) corresponds to about 110 times its volume of oxygen. A suitable stabiliser may be added.

CHARACTERS

Appearance

Colourless, clear liquid.

IDENTIFICATION (see hydrogen peroxide solution (3%))

эA. To 1 ml add 0.2 ml of dilute sulphuric acid R and 0.25 ml of 0.02 M potassium

permanganate. The solution becomes colourless with evolution of gas.

эB. To 0.05 ml add 2 ml of dilute sulphuric acid R, 2 ml of ether R and 0.05 ml of potassium

chromate solution R and shake. The ether layer is blue.

эC. It complies with the requirement for the content of H2O2.

TESTS

Acidity

To 10 ml add 100 ml of water R and 0.25 ml of methyl red solution R. Not less than 0.05 ml and not more than 0.5 ml of 0.1 M sodium hydroxide is required to change the colour of the indicator.

Organic stabilisers

Maximum 500 ppm.

Non-volatile residue

Maximum 2 g/l.

Allow 10 ml to stand in a platinum dish until all effervescence has ceased, cooling if

necessary. Evaporate to dryness on a water-bath and dry at 100-105 °C. The residue weighs a maximum of 20 mg.

ASSAY (see hydrogen reoxide solution (3%))

(BrPh, SPU, add. 1). Permanganatometry, direct titration (nonindicator method).Dilute 1.00 g to 100.0 ml with water R. To 10.0 ml of this solution add 20 ml of dilute sulphuric acid R. Titrate with 0.02 M potassium permanganate until a pink colour is obtained.

1 ml of 0.02 M potassium permanganate is equivalent to 1.701 mg of H2O2 or 0.56 ml of oxygen.

STORAGE

Protected from light, and if the solution does not contain a stabiliser, at a temperature below 15 °C.

LABELLING

If the solution contains a stabiliser, the label states that the contents are stabilised. The competent authority may require that the name of the stabiliser be stated on the label.

CAUTION

It decomposes vigorously in contact with oxidisable organic matter and with certain metals and if allowed to become alkaline.

Ph Eur

Action and use

Antiseptic; deodorant.

When hydrogen peroxide is prescribed or demanded, Hydrogen Peroxide Solution (6 per cent) shall be dispensed or supplied.

Ph Eur

Hydroperitum non-pharmacopoeial drug

Perhydrit

H₂O₂

H₂NCONH₂×H₂O₂

It is complex compound of hydrogen peroxide H₂O₂ and urea H₂NCONH₂.

Consists 33–35 % of Н₂О₂.

CHARACTERS

Appearance

White, crystalline powder.

Solubility

Freely soluble in water, soluble in alcohol.

IDENTIFICATION

1. Reaction for H₂O₂ – formations of perchromic acids (see hydrogen peroxide solution).

2. Reaction for urea H₂NCONH₂ (biuret reaction).

At slowly heating to 150–160 ° С urea decomposed with allocated ammonia NH₃ and formation of biuret H₂NCONHCONH₂:

isocyanic acid

biuret

Tautomerism (dynamic isomerism):

imide–form of biuret

At interaction of biuret (imide–form) with Copper(II) ions in the alkali medium observed characteristic violet colour, because there is formation chelate complex:

chelate complex of violet colour

Assay. Iodometry, substitute titration. (At titration interacts only H₂O₂).

H₂O₂ + 2KI + H₂SO₄ = I₂ + K₂SO₄ + 2H₂O

2I^– – 2е ® I₂⁰ 1

H₂O₂ + 2H⁺ + 2е ® 2H₂O 1

H₂O₂ + 2I^– + 2H⁺ ® I₂ + 2H₂O

I₂ + 2Na₂S₂O₃ = 2NaI + Na₂S₄O₆

I₂ + 2е ® 2I^–

2S₂O₃^2– – 2е ® S₄O₆^2–

Е_m(H₂O₂) =М.м./2 Е_m(Na₂S₂O₃) = М.м.

STORAGE

In an airtight container, at t ≤ 20ºC .

Action and use

Antiseptic; instead of hydrogen peroxide solution.

Magnesium peroxide BrPh 2007, SP X

(Ph Eur monograph 1540)

Magnesii peroxydum

MgO₂ × MgO

Magnesium peroxydatum

Magnium peroxydatum

DEFINITION

Magnesium peroxide is a mixture of magnesium peroxide and magnesium oxide. It contains not less than 22.0 per cent and not more than 28.0 per cent of MgO₂ (M_r 56.30).

CHARACTERS

A white or slightly yellow, amorphous, light powder, practically insoluble in water and in alcohol. It dissolves in dilute mineral acids.

OBTAINING

1. Interaction magnesium chloride with alkali and hyrgen peroxide at t=7–8 °С:

MgCl₂ + 2KOH = 2KCl + MgО + H₂O

MgО + H₂O₂ = MgО₂+ H₂O

Obtained products is necessary to wash by alcohol and dry in the vacuum.

2. Electrolysis of 20 % magnesium chloride solution MgCl₂; in the cathode is formatted magnesium peroxide MgО₂.

3. Oxidation of magnesium oxide by oxygen at t = 500 °С:

2MgО+ O₂ = 2MgО₂

IDENTIFICATION

A. (BrPh 2007, SP X). Reaction for Magnesium cations after drug dilution in the mineral acid. Dissolve about 15 mg in 2 ml of dilute nitric acid R and neutralise with dilute sodium hydroxide solution R. The solution gives the reaction of magnesium (2.3.1).

Magnesium and Magnesium Salts

Dissolve about 15 mg of the substance to be examined in 2 ml of water R or use 2 ml of the prescribed solution. Add 1 ml of dilute ammonia R1. A white precipitate is formed that dissolves on addition of 1 ml of ammonium chloride solution R. Add 1 ml of disodium hydrogen phosphate solution R. A white crystalline precipitate is formed.

MgSO₄ + Na₂HPO₄ + NH₄OH MgNH₄PO₄¯ + Na₂SO₄ + H₂O

white crystalline precipitate

of magnesium-ammonium phosphate

B. (BrPh 2007, SP X). Reaction for peroxide group (after dilution in the mineral acid). Dissolve 0.1 g in 2 ml of dilute sulphuric acid R and dilute to 10 ml with water R. Shake 1 ml of the solution with 5 ml of ether R and 0.5 ml of potassium dichromate solution R1. The ether layer is blue.

MgO₂+ H₂SO₄ = MgSO₄ + H₂O₂

H₂O₂ + H₂Cr₂O₇ = H₂Cr₂O₈ + H₂O

TESTS

Solution S1

Dissolve cautiously 5.0 g in 40 ml of hydrochloric acid R1. Cautiously evaporate the solution to a volume of 10 ml and dilute to 100 ml with a mixture of equal volumes of acetic acid R and distilled water R. Filter, if necessary, through a previously ignited and tared porcelain or silica filter crucible of suitable porosity to give a clear filtrate. Keep the residue for the test for acid insoluble substances.

Solution S2

Dilute 5 ml of solution S1 to 25 ml with distilled water R.

Appearance of solution

Solution S1 is not more intensely coloured than reference solution B₄ (2.2.2, Method II).

Acid insoluble substances

Any residue obtained during the preparation of solution S1, washed, dried and ignited at 600 °C, weighs not more than 5 mg (0.1 per cent).

Acidity or alkalinity

To 2.0 g add 100 ml of carbon dioxide-free water R and heat to boiling for 5 min. Filter whilst hot through a sintered-glass filter (40), allow to cool and dilute to 100 ml with carbon dioxide-free water R. To 15 ml of the filtrate, add 0.1 ml of phenolphthalein solution R. The solution is red. Not more than 0.2 ml of 0.1 M hydrochloric acid is necessary to change the colour of the indicator. Keep the filtrate for the test for soluble substances.

Soluble substances

Take 50 ml of the filtrate obtained in the test for acidity or alkalinity, evaporate to dryness and dry at 100 °C to 105 °C. The residue weighs not more than 15 mg (1.5 per cent).

Chlorides (2.4.4)

Dissolve 50 mg in 5 ml of dilute nitric acid R and dilute to 15 ml with water R. The solution complies with the limit test for chlorides (0.1 per cent).

Sulphates (2.4.13)

3 ml of solution S2 diluted to 15 ml with distilled water R complies with the limit test for sulphates (0.5 per cent).

Arsenic (2.4.2)

5 ml of solution S1 complies with limit test A for arsenic (4 ppm).

Calcium (2.4.3)

1 ml of solution S2 diluted to 15 ml with distilled water R complies with the limit test for calcium (1.0 per cent).

Iron (2.4.9)

2 ml of solution S2 diluted to 10 ml with water R complies with the limit test for iron (500 ppm).

Heavy metals (2.4.8)

To 20 ml of solution S1 add 15 ml of hydrochloric acid R1 and shake with 25 ml of methyl isobutyl ketone R for 2 min. Allow to stand, separate the aqueous layer and evaporate to dryness. Dissolve the residue in 1.5 ml of acetic acid R and dilute to 30 ml with water R. 12 ml of the solution complies with limit test A for heavy metals (30 ppm). Prepare the standard using lead standard solution (1 ppm Pb) R.

ASSAY

(BrPh 2007, SP X). Permanganatometry, direct titration (after dissolution in the mineral acid). Dissolve 80.0 mg, shaking cautiously, in a mixture, previously cooled to 20 °C, of 10 ml of sulphuric acid R and 90 ml of water R. Titrate with 0.02 M potassium permanganate until a pink colour is obtained.

1 ml of 0.02 M potassium permanganate is equivalent to 2.815 mg of MgO₂.

MgО₂+ H₂SO₄= MgSO₄ + H₂O₂

5H₂O₂ + 2KMnO₄ + 3H₂SO₄ = 2MnSO₄ + K₂SO₄ + 5O₂ + 8H₂O

5H₂O₂ + 2MnО₄^– + 6H⁺ ® 2Mn²⁺ + 5O₂ + 8H₂O

E_m=М.m./2

STORAGE

Store protected from light.

Ph Eur

Action and use

Oral antiseptic and adsorption agent.

Browse: British Pharmacopoeia 2009 SPU, add. 1

British Pharmacopoeia Volume I & II

Monographs: Medicinal and Pharmaceutical Substances

Potassium Permanganate

Potassium Permanganate

General Notices

(Ph Eur monograph 0121)

Kalii permanganas

Kalium hypermanganicum

KMnO₄

ээ158.0ээ7722-64-7

DEFINITION

Content

99.0 per cent to 100.5 per cent.

OBTAINING

1. Fusion of pyrolusite with alkali in the presence of oxidizers.

а) 2MnО₂ + 4KOH + O₂ 2K₂MnО₄ + 2H₂O

MnО₂ + 4OH^– – 2е ® MnО₄^2– + 2H₂O

O₂ + 4H⁺ + 4е ® 2H₂O

2MnО₂ + 4OH^– + O₂ ® 2MnО₄^2– + 2H₂O

б) 2K₂MnО₄ + Cl₂ = 2KMnО₄ + 2KCl

MnО₄^2– – 1е ® MnО₄^–

Cl₂ + 2е ® 2Cl^–

2MnО₄^2– + Cl₂ ® 2MnО₄^– + 2Cl^–

2. Electrolysis of potassium manganate solution K₂MnО₄_.

K₂MnО₄ « 2К⁺ + MnО₄^2–

Cathode⁽^–): Н₂О; 2К⁺ Н₂О + 2е ® 2ОН^– + Н₂

Anode⁽⁺⁾: Н₂О; MnО₄^2– MnО₄^2– – 1е ® MnО₄^–

General reaction of electrolysis:

2K₂MnО₄ + 2HOH electrolysis H₂ + 2KMnО₄ + 2KOH

CHARACTERS

Appearance

Dark purple or brownish-black, granular powder or dark purple or almost black crystals,

usually having a metallic lustre.

Solubility

Soluble in cold water, freely soluble in boiling water.

It decomposes on contact with certain organic substances.

Chemical properties

KMnО₄ – strong oxidizer (Е = 1,51В), potassium permanganate can to oxidize different reducers (for examples, Н₂О₂, ions Fe²⁺, sulphites SO₃^2–, nitrites NO₂^–and other) and in the different mediums can be reduced to Mn²⁺ (occurrence decolouration of solution), MnО₂ (is formed brown precipitate) or MnО₄^2– (occurrence a green colour):

+H⁺

Mn⁺² (decolouration of solution)

+HOH

KMn⁺⁷O₄Mn⁺⁴O₂¯ + KOH (brown precipitate)

+OH^–

К₂Mn⁺⁶O₄ (green colour)

For examples, reduction of sodium sulphite Na₂SO₃ by means of KMnО₄ in the different mediums:

2KMnO₄+ 5Na₂SO₃ + 3H₂SO₄ = 2MnSO₄ + 5Na₂SO₄ + K₂SO₄ + 3H₂O

2KMnO₄+ 3Na₂SO₃ + H₂O = 2MnO₂ + 3Na₂SO₄ + 2KOH

2KMnO₄+ Na₂SO₃ + 2KOH = K₂MnO₄ + Na₂SO₄ + 3H₂O

Strong oxidizing properties is base for reactions of identification and assay.

IDENTIFICATION

эA. (BrPh, SPU, add. 1). Reaction with ethanol in the presence of alkali. Dissolve about 50 mg in 5 ml of water R and add 1 ml of ethanol (96 per cent) R and 0.3 ml of dilute sodium hydroxide solution R. A green colour develops. Heat to boiling. A dark brown precipitate is formed.

C₂H₅OH + 2KMnО₄ + 2КОН = CH₃CНO + 2К₂MnО₄+ 2Н₂О

green colour

MnО₄^– + 1e ® MnО₄^2–

С₂Н₆О + 2ОH^–– 2е ® С₂Н₄О + 2Н₂О

2MnО₄^– + С₂H₅OH + 2ОН^–® 2MnО₄^2– + CH₃CНO + 2Н₂О

At heating potassium permanganate is decomposed:

2KMnО₄ ® К₂MnО₄ + MnО₂¯ + 5O₂

4KMnО₄ + 2H₂O = 4KOH + 4MnО₂¯ + 3O₂

dark brown precipitate

эB. (BrPh, SPU, add. 1). Filter the mixture obtained in identification test A. The filtrate gives reaction (b) of potassium (2.3.1).

Potassium and Potassium Salts

B. Reaction with sodium cobaltinitrite in the acetic-acid medium. Dissolve about 40 mg of the substance to be examined in 1 ml of water R or use 1 ml of the prescribed solution. Add 1 ml of dilute acetic acid R and 1 ml of a freshly prepared 100 g/l solution of sodium cobaltinitrite R. A yellow or orange-yellow precipitate is formed immediately.

2К⁺ + Na⁺ + [Co(NO₂)₆]^3– → K₂Na[Co(NO₂)₆]↓

yellow or orange-yellow precipitate

TESTS

Solution S

Dissolve 0.75 g in 25 ml of distilled water R, add 3 ml of ethanol (96 per cent) R and boil for 2-3 min. Cool, dilute to 30 ml with distilled water R and filter.

Appearance of solution

Solution S is colourless (2.2.2, Method II).

Substances insoluble in water

Maximum 1.0 per cent.

Dissolve 0.5 g in 50 ml of water R and heat to boiling. Filter through a tared sintered-glass filter (16) (2.1.2). Wash with water R until the filtrate is colourless and collect the residue on the filter. The residue, dried in an oven at 100-105 °C, weighs a maximum of 5 mg.

Chlorides (2.4.4)

Maximum 200 ppm.

Dilute 10 ml of solution S to 15 ml with water R.

Sulphates (2.4.13)

Maximum 500 ppm.

Dilute 12 ml of solution S to 15 ml with distilled water R.

ASSAY

(BrPh, SPU, add. 1). Iodometry, substitute titration. Dissolve 0.300 g in water R and dilute to 100.0 ml with the same solvent. To 20.0 ml of the solution add 20 ml of water R, 1 g of potassium iodide R and 10 ml of dilute hydrochloric acid R. Titrate the liberated iodine with 0.1 M sodium thiosulphate, using 1 ml of starch solution R as indicator.