This Notes is compiled for B. Pharm students of Tribhuvan University, Nepal.

1. Unit A: Oxygen and compounds of oxygen like nitrous oxide, carbon dioxide, hydrogen peroxide, oxygen
therapy and anesthetic gases/ anesthetic Ether.
a. Oxygen: Oxygen is manufactured chiefly by fractional distillation of liquid air and by electrolysis of water.
Oxygen prepared by fractionation of liquid air is always liable to contain nitrogen and inert gases. In the
manufacture of oxygen from water, a solution of sodium hydroxide is usually employed, since pure water is not
a conductor. The solution is electrolysed in tanks with iron electrodes and the hydrogen and oxygen evolved are
collected separately under pressure in steel cylinders. Oxygen prepared by electrolysis of water usually contains
traces of hydrogen, and sometimes of ozone.
Tests for purity: Tests for acidity or alkalinity; carbon dioxide; and oxidising substances.
 In testing oxygen for carbon dioxide, the gas is passed slowly through a 3 % solution of barium
hydroxide. When a quantity of gas equivalent to 1000 ml. at STP has been passed, the turbidity
produced is compared with that formed by addition of a specified quantity of sodium bicarbonate to
another portion of barium hydroxide solution.
 Oxidising substances (such as ozone) are detected by formation of a blue colour due to iodine liberated
from a solution containing potassium iodide and starch.
Assay: It contains not less than 99.0 per cent, v/v of 02.
Hempell burette fitted with a three-way tap is generally used for the gasometric assay of Oxygen
It consists of the measuring tube and the levelling tube connected by about three feet of rubber tubing: The
measuring tube should be perfectly dry. The levelling tube contains an alkaline solution of pyrogallol of suitable
concentration and is raised so that the base is about level with the top of the measuring tube, care should be
taken to avoid the presence of air bubbles in the rubber tubing, and the levelling tube, except when it is being
used, should be corked to prevent access of air.
The three-way tap is turned so as to connect the measuring tube to air, the top tap is opened, and a stream of gas
from the supply which is being examined is passed through the measuring tube for about two minutes, in order
to displace all the air. Both taps are then closed, the levelling tube is uncorked, and the three-way tap is opened
so as to admit the alkaline pyrogallol solution into the measuring tube. After being shaken until no further
contraction in volume takes place, the liquid is adjusted to the same level in the two tubes, and the volume of
residual gas is read off. It should represent not more than 1 per cent, of the original volume of the sample taken.
An apparatus which is particularly convenient for the rapid assay of oxygen is the Franke burette. The dry
burette is filled with the gas by passing a stream through for two minutes or so. and the taps are then closed. The
plug with tap is removed, the receiver is completely filled with alkaline pyrogallol solution, and the plug is
replaced, its tap being closed after replacement. By opening the centre tap, the solution is allowed to flow into
the burette, which may be gently shaken to ensure complete absorption of oxygen, The burette is then inverted,
and the centre tap is opened so as to allow all the absorbent to flow back into the receiver. The centre tap is
closed, and the burette is turned right way up again and lowered into a cylinder of water. The bottom tap is
opened, and, after the water has been adjusted to the same level inside and outside the burette, the volume of
unabsorbed gas is read on the scale

2. b. CO2
It is manufactured by the action of acids on Carbonates.
Tests for acid & SO2; PH3, H2S and organic reducing substances and CO.
 Test for acid and SO2: Water coloured with methyl orange is saturated by passing through it a measured
volume of CO2, which has been previously freed, from any trace of acid by passing through NaHCO3
solution. A similar measured vol. of CO2 is then passed directly (without previous treatment with
NaHCO3) through a similar indicator soln, when no further change in colour should result. The reason for
saturating the first indicator soln. with acid free CO2 is that pure CO2 slightly affects the colour of methyl
orange.
 Phosphine, H2S and other organic reducing substances are detected by a dark colouration produced when
the gas is passed through Ammonium Ag2O solution due to formation of Ag3P, Ag2S or Ag.
 In testing for CO, a measured volume of CO2 in gaseous phase is passed through a series of glass wash
bottles containing Chromic acid and Sulphuric acid mixture, then solid KOH then P2O5. Chromic acid
removes traces of oily matter and hydrocarbons. KOH removes CO2, oxides of N2 halogens and P2O5
removes moisture. The dry gas is then passed through a tube containing dry heated I2O5, which oxidizes
any traces of CO.
I2O5 + 5CO I2 + 5CO2
Assay: 99 % of CO2 v/v
Assay is determined by the use of Hempel apparatus. The burette is filled with the gas and the top of the
measuring tube is connected to an absorption pipette (Hempel pipette) by means of a bent capillary tube and
two short lengths of rubber tubing. The pipette contains enough 50% KOH solution to fill the whole of the
lower and part of the upper bulb. The top tap of the burette is opened, and the leveling tube (which for this assay
contains water) is raised above so as to drive the whole of the gas into the lower bulb of the pipette. Gentle
rocking of the pipette for two or three minutes ensures complete absorption of carbon dioxide and the small
quantity of residual gas is then drawn back into the burette by lowering the leveling tube.The tap is turned off as
soon as the capillary has become filled with liquid. After the levels in the two burette tubes have been adjusted,
the volume of the unabsorbed gas is read
c. Nitrous Oxide (N2O):
NH4NO2 N2O + 2H2O
Decomposes at little above melting point. N2O is a colourless gas. Liquefies under 50 atm. pressure and 15o
C.
Test for purity: performed for acidity & alkalinity, halides, H2S, AsH3, PH3, CO, CO2, NO, NO2 and water
vapour.
 Acidity and alkalinity are tested by colorimetric comparison on a solution of methyl red, which has
been adjusted to about the middle of its transition interval by addition of N/100 HCl.
 Halides are detected by an opalescence formed when the gas is passed through dil. AgNO3 soln. H2S is
recognized due to formation of Ag2S by a darkening.

3.  In the test for AsH3 & PH3, the gas is passed through cotton wool moistened with Lead Acetate to
remove any halides or H2S. The gas is then passed through a soln. of AgNO3 in quinoline, when any
Silver derivative formed will change the colour of the soln.
 Test for CO is similar to that used for CO2.
 NO & NO2 are tested by spectrophotometric methods.
 Water is determined by absorption in P2O5 and CO2 by absorption in Ca(OH)2.
Assay: A quantity of about 50 ml. of the gas is taken into an evacuated vessel and this is immersed in liquid O2
or N2 for sometime. The uncondensed gas is then drawn off into a small eudiometer tube and measured. The
uncondensed gas in this assay N2 with perhaps traces of O2 should not exceed 1%.
d. Anesthetic Ether/ Diethyl ether
It consists of diethyl ether with suitable stabilizers not greater than 0.002%. Stabilizers are reducing agent to
prevent the development of peroxides. Substances used are di or poly-hydric phenols, propyl gallate.
Physical parameters: melting point, boiling point, weight per ml, distillation range, density, viscosity,
refractive index and optical rotation.
Test for purity: Tests for acetone and aldehydes, foreign odour, methyl alcohol, peroxides, acidity and non-
volatile matter.
 Acetone and aldehyde are detected by means of Nessler's reagent. Even with traces of acetone a pale
yellowish mercury compound is precipitated. Can detect 1 part of acetone per 1000 ml.
 Aldehydes reduce Nessler's solution, if present in quantity produces a greyish-black colour even small
traces of aldehyde cause a yellowish brown-coloration.
 Another test for aldehyde and acetone is the formation of brown colour when ether is allowed to stand
over solid KOH.
 Test for peroxides involve the use of KI and starch. Traces of peroxides liberate I2 which give a
reddish-brown colour.
Storage: Anaesthetic ether should not be closed by ordinary corks. Corks coated with metal foil are used,
because of the risk of contamination with extractive matter from the cork.
e. Hydrogen peroxide (H2O2)
Preparation of H2O2
 BaO2 + H2SO4 BaSO4 + H2O2
 Na2O2 + H2SO4 Na2SO4 + H2O2
 50 % H2SO4 is electrolysed to give H2S2O8
2H2SO4 H2S2O8 + H2
H2S2O8 (persulphuric acid) is vaccum distilled
H2S2O8 + 2H2O 2H2SO4 + H2O2
Properties: H2O2 is a strong oxidizing agent. It is unstable in alkaline solution or under catalytic influences of
Cu, Fe or Mg ions. Stability is increased by making it slightly acidic with H2SO4 or H3PO4 or by addition of
very small quantities of inorganic or organic preservatives or stabilizers such as Boric acid, Urea, acetanilide or
hexamine.
Test: A few drops of H2O2 is added to a solution of ether and acidified K2CrO4. A deep blue colour is produced
between the ether and aqueous layer. The colour is transferred to ether on shaking.
Official solution: 5 – 7 % w/v or 20 volumes. Yields 20 times its vol. of Oxygen.
Assay : Titration with N/10 KMnO4 in presence of dil.H2SO4
Unit B: Antacids: Aluminum hydroxide, Calcium carbonate, Sodium bicarbonate, Magnesium trisilicate,
Magnesium carbonate (light and heavy), Magnesium oxide (light and heavy), Magnesium hydroxide
mixture.
a. Aluminium Hydroxide Gel:
Al2(SO4)3 + (NH4)2CO3 Al2(CO3)3 2Al(OH)3 + CO2
Test for purity: alkalinity, ammonium salts, As, Pb, chloride, sulphate and neutralizing capacity.
Neutralizing capacity is assessed by measurements at successive intervals of time of the pH of a suspension of
the material in a medium, which is approx. N/20 with respect to HCl.
3H2O

4. Assay: The gel is dissolved in conc. HCl cooled and diluted. A known excess of M/20 Sodium EDTA is added
and the mixture is neutralized with methyl red indicator with aid of NaOH. The neutral mixture is heated for
half an hour to ensure that complexation is complete, hexamine is added and a back titration with M/20
Plumbous Nitrate is carried out using xylenol orange as indicator.
Al+3
+ H2Y-2
+ H2O Al(OH)HY-
+ 2H+
1000 ml of M/20 Sod.Edetate is equivalent to 1/20 of Al(OH)3
b. MgO (Light)
Preparation: Light MgO is prepared by heating the light carbonate to dull redness until CO2 is no longer
evolved.
3MgCO3.Mg(OH)2,3H2O 4MgO + 3CO2 + 4H2O
Properties: MgO is a white powder, which slowly absorbs water and CO2 from the atmosphere forming basic
carbonates. It is very slightly soluble in water but enough to form a solution which is distinctly alkaline to
phenolphthalein and contains Mg(OH)2
Tests : As, Ca, Cu, Fe, Cl-
, SO4-2
, soluble matter, Pb, and loss on ignition.
 Test for Cu, Fe, Pb, is performed as their sulphides from dark colourations
 Calcium is tested by precipitation as Sulphate in aquous alcoholic solution (in which CaSO4 is very
sparingly soluble). The precipitate after being allowed to stand for several hours is collected in Gooch
crucible washed with aq. alcoholic H2SO4, dried , ignited and weighed.
 Light MgO is required to lose on ignition not more that 5% of its weight. This provides a limit for CO2
& H2O.
 Lead is extracted as the dithizone-complex, the complex is then compared spectrophotometrically with a
control
Assay: A sample is ignited to constant weight to remove moisture and is dissolved in excess 1N H2SO4, the
excess acid is back titrated with 1N alkali.
1000 ml of 1N acid is equivalent to 1/2MgO.
c. MgCO3 (Heavy): Hydrated Basic Carbonate 3MgCO3. Mg(OH)2. 4H2O
It consists of 125 parts MgSO4; 150 parts Na2CO3 and 250 parts water. The solutions are mixed and evaporated
to dryness. The residue of MgCO3 and Na2SO4 is digested with 500 parts boiling water for ½ hour. The
insoluble carbonate is then collected on a filter, washed until free from sulphate and dried in a water oven.
Properties: Heavy MgCO3 is a white, granular powder, insoluble in water. When heated to redness it loses CO2
and water leaving a residue of MgO.
Tests, Ca, Cu, Fe, Pb, Cl-
, SO4-2
, residue on ignition and soluble matter.
 Calcium is tested by precipitation as Sulphate in aquous alcoholic solution (in which CaSO4 is very
sparingly soluble). The precipitate after being allowed to stand for several hours is collected in Gooch
crucible washed with aq. alcoholic H2SO4, dried , ignited and weighed.
 Test for Cu, Fe, Pb, is performed as their sulphides from dark colourations
 Lead is extracted as the dithizone-complex, the complex is then compared spectrophotometrically with a
control.
 The substance shall lose in ignition 55 to 58 % of its wt.
d. MgCO3 (Light) : 3MgCO3.Mg(OH)2,3H2O
It consists of 125 parts MgSO4, 150 parts Na2CO3 and 1000 parts cold water. The solutions are mixed and
boiled for 15 min., washed and dried in a water oven.
Tests, Ca, Cu, Fe, Pb, Cl-
, SO4-2
, residue on ignition and soluble matter.
 Calcium is tested by precipitation as Sulphate in aquous alcoholic solution (in which CaSO4 is very
sparingly soluble). The precipitate after being allowed to stand for several hours is collected in Gooch
crucible washed with aq. alcoholic H2SO4, dried , ignited and weighed.
 Test for Cu, Fe, Pb, is performed as their sulphides from dark colourations
 The substance shall lose in ignition 55.8% of its wt.
e. Mg(OH)2 : Milk of Magnesia
Preparation : MgO is mixed with NaOH soln. The solution after dilution with water is poured into a solution of
MgSO4 with constant stirring. The ppt. is allowed to settle and the clear liquid is siphoned or decanted off. The
residue is collected on a filter, washed until free from SO4 and mixed with requisite quantity of purified water.
2NaOH + MgSO4 Na2SO4 + Mg(OH)2

5. Tests : As, Pb and SO4-2
Assay : A weighed quantity of the mixture is treated with a known vol. of 1N H2SO4 and the excess acid is
determined in the clear soln. by titration with 1N NaOH.
H2SO4 + Mg(OH)2 MgSO4 + H2O
1 ml of 1N acid is equivalent to ½ ml of Mg(OH)2
f. Magnesium Trisilicate: 2MgO. 3SiO2. 3H2O or 2MgO. 3SiO2. 4H2O
Preparation: Prepared by precipitation from solution of MgSO4 and NaSiO2
Properties: It is a white powder, insoluble in water. Decomposes with acids to form the Mg salt and silicic acid.
Alkali Carbonates decompose it with formation of MgCO3. Magnesium trisilicate is used as an antacid to
neutralize excessive amounts of HCl in the stomach. Does not evolve CO2 like carbonates and bicarbonates and
also owing to its slow reaction with HCl of exerting continuous control over gastric acidity.
Test for purity: As, Fe, Pb, Chloride, Sulphate, acid absorption and loss on ignition.
 The test for acid absorption is carried out with a weighed quantity of the substance and N/20 HCl kept
at 37oC for 3 hours.
 Test for SO4-2
and Cl-
are done by BaCl2 and AgNO3.
Assay: Must contain 29.5 – 32.0 % MgO and 65.0 – 68.5 % of SiO2 calculated with reference to the substance.
Ignited at about 1000o
C, 2MgO,3SiO2 would contain 30.9% MgO and 69.1% SiO2.
Unit D: Sodium chloride and sodium chloride injection, Dextrose and sodium chloride injection,
Potassium chloride tablets/injection, Calcium chloride, Calcium gluconate injection, Calcium lactate,
Sodium acetate, Potassium acetate, Sodium citrate, Sodium lactate, Lactated Ringer’s solution, ORS
a. NaCl
Preparation: It is manufactured by evaporation of sea-water in shallow pans.
Very pure NaCl, for analytical purposes is prepared by passing HCl gas into a concentrated solution of the salt.
NaCl being much less soluble in HCl crystallizes out, leaving the impurities in soln.
Tests: Aciditiy,alkalinity, As, Ba, Ca, Mg, Fe, Pb, Br-
, I-
, SO4-2
and loss on drying.
 Test for Fe, Pb, is performed as their sulphides from dark colourations
 Test for SO4-2
and Cl-
are done by BaCl2 and AgNO3.
Assay : A known quantity of the substance is reacted with excess N/10 AgNO3. The amount of AgNO3
consumed is determined by titration with NH4SCN with Potassium Chromate indicator.
AgNO3 + NaCl AgCl + NaNO3
1000ml of N/10 AgNO3 is equivalent to 1/10 NaCl
b. Sodium Chloride Injection:
This is a sterilized solution of NaCl, prepared water for injection, which is designed to be isotonic with blood.
Tests: Aciditiy,alkalinity, As, Ba, Ca, Mg, Fe, Pb, Br-
, I-
, SO4-2
and loss on drying.
 Test for SO4-2
and Cl-
are done by BaCl2 and AgNO3
Assay : A known quantity of the substance is reacted with excess N/10 AgNO3. The amount of AgNO3
consumed is determined by titration with NH4SCN with Potassium Chromate indicator.
AgNO3 + NaCl AgCl + NaNO3
1000ml of N/10 AgNO3 is equivalent to 1/10 NaCl
c. Sodium Chloride & Dextrose injection:
This is a sterile solution made isotonic with blood by means of dextrose. It is assayed for NaCl as in NaCl
injection and for dextrose as in dextrose injection.
d. Sodium Lactate Injection:
Is made by heating Lactic acid with NaOH solution under pressure in an autoclave to hydrolyze the lactic acid
anhydrides, neutralizing the solution with HCl then diluting to volume with water for injection. The injection is
sterilized.
Assay: A measure volume is evaporated to dryness. The residue is dissolved in a mixture of acetic anhydride
and glacial acetic acid and titrated with N/10 Perchloric acid using crystal violet as indicator.
1000 ml of N/10 acid is equivalent to 1/10 C3H5NaO3
e. CaCl2

6. Preparation: Prepared by adding pure CaCO3 in slight excess to hot somewhat diluted HCl, filtered when
reaction is complete and evaporating to syrup. CaCl2 then crystallizes when cooled to about 10o
C with
refrigeration if necessary. The crystals are separated and transferred immediately to stoppered bottles. The
crystals deliquesce in moist air, effloresce in dry air and melt in their water of crystallization when gently
warmed. CaCl2 is used for preparing solutions for intravenous or intra muscular injections.
Tests : acidity or alkalinity, clarity and colour of soln. As, Pb, SO4-2
, Al, Fe, PO4-3
and matter insoluble in
HCl and alcohol-insoluble matter.
 An aqueous solution is practically neutral to bromothymol blue and the quantity of standard acid or
alkali required to bring it to the neutral point gives a measure of the proportion of alkali or acid as
impurity.
 Test for SO4-2
and Cl-
are done by BaCl2 and AgNO3.
Assay : A known weight of the substance is taken 1 ml of buffer of pH 10 and some drops of Eriochrome
Black T is added. The solution is titrated with M/20 Sodium EDTA and the volume is noted.
Reaction : Ca+2
+ H2Y-2
CaY-2
+ 2H+
Ca+2
+ In-3
CaIn-
CaIn-
+ H2Y-2
CaY-2 + HIn-2
Red Blue
1ml of M/20 Sodium EDTA is equivalent to 1ml of M/20 CaCl2
f. CaCO3
Preparation:
CaCl2 + Na2CO3 CaCO3 + NaCl
The solution is filtered, washed with boiling water till free from chloride and dried.
Properties: CaCO3 is a fine, white powder, which under a microscope is seen to consist of minute hexagonal
crystals. Ordinary water dissolves about 0.013 g/l but water-containing CO2 dissolves about 0.3 to 0.5 g/l owing
to the formation of
CaCO3 + CO2 + H2O Ca(HCO3)2
Tests for purity: Al, Fe, As, PO4-3, Pb, Cl-, SO4-2, soluble alkali and loss on drying.
 Test for SO4-2
and Cl-
are done by BaCl2 and AgNO3.
Assay: A known weight of the substance is dissolved in 1N HCl after removal of CO2 by boiling, the solution is
cooled and the excess of HCl is determined by titration with 1N NaOH using methyl orange as indicator.
The precipitated chalk is used externally as a dentifrice because it has mild abrassive quality. It forms a
common ingredient of tooth powder and toothpaste
g. Calcium Lactate:
Preparation: It is prepared by adding a slight excess of CaCO3 to a hot dilute solution of Lactic Acid and
boiling the mixture for ½ hour.
CaCO3 + CH3.CHOH.COOH (CH3.CHOH.COO)2 Ca + CO2 + H2O
The hot liquid is filtered and the filtrate is evaporated to crystallization point. The object of boiling is to
convert the anhydrides and free lactic acid into Calcium Lactate.Calcium Lactate is a prepared as colourless
crystal or as a white powder. The salt is a pentahydrate and can be completely dehydrated by heating to 100
oC.
Tests: acidity or alkalinity, As, Fe, Pb, Cl-
, SO4-2
and reducing sugars.
 Test for SO4-2
and Cl-
are done by BaCl2 and AgNO3.
Assay: as in CaCl2.
h. Calcium Gluconate:
Preparation: It can be prepared by boiling a solution of gluconic acid with a slight excess of CaCO3, filtering
and crystallizing the product from the filtrate.
Properties: Calcium Gluconate is a crystalline powder, it readily forms a supersaturated solution. It is used for
administering Ca, because it can be given by intravenous injection.
Tests : acidity, alkalinity, As, Pb, Cl-
, SO4-2
, dextrose and sucrose.
 Test for SO4-2
and Cl-
are done by BaCl2 and AgNO3.
 Dextrose and sucrose may be present since gluconic acid is made by fermentation of sugar solutions.
They are tested by means of Fehling's soln.
Assay: as in CaCl2.

7. i. Sodium Citrate:
Preparation: It is prepared by mixing hot solutions of citric acid and sodium carbonate in calculated proportions
and crystallizing the product.
Na2CO3 + H3C6H5O7 Na3C6H5O7 + CO2 + H2O
Tests: acidity or alkalinity, Cl-,SO4-2, readily carbonisable substances. As, Pb, and oxalate.
 Test for SO4-2
and Cl-
are done by BaCl2 and AgNO3.
 Acidity or alkalinity is measured by vol. of standard NaOH or HCl required to neutralize a soln. of the
salt to thymol blue using phenolphthalein as indicator.
 Readily carbonisable substances are detected by heating the subs. at water-bath temperature with
conc.H2SO4 in the absence of light: under these conditions pure sodium citrate does not darken.
Assay: A weighed qty. of the substance is heated, preferably in a large Ni crucible until inflammable gases
cease to be evolved and a dark grey charred residue containing Na2CO3 remains. The temperature is raised very
slowly as decomposition proceeds until finally the crucible is heated to dull redness. The residue is boiled with
water and a measured vol. of N/2 HCl is added and the liquid is filtered from the carbonaceous residue. It is
then boiled with two quantities of water, which are passed through the filter. The excess of acid in the combined
filtrate is titrated with N/ NaOH with methyl orange.
1 ml of N/2 HCl is equivalent to 1/6 ml of Na3C6H5O7
Unit C: Protective and adsorbents
a. Purified Talc:
It is a silicate of Mg of the composition 3MgO.4SiO2.H2O, which may contain a small proportion of aluminium
silicate. For pharmaceutical purposes talc is purified by boiling it with HCl to remove soluble matter and
washing the residue until free from acid.
Tests: acidity, alkalinity, Fe, acid-soluble matter, water soluble matter, loss on drying, loss on ignition.
 Official limit for loss of ignition is 6 %.
b. Heavy Kaolin or China clay:
Kaolin consists mainly of aluminium silicate Al2O3.2SiO2.2H2O with traces of compounds of Mg, Ca, Fe.
Heavy Kaolin for pharmaceutical purposes is prepared by powdering the natural substance and freeing it from
gritty particles.
Tests: As, Pb, Cl-, loss on drying, loss on ignition and soluble matter.
 The official limit is 15% loss on ignition.
c. Light Kaolin:
Light Kaolin is a finely divided form of Kaolin specially intended for internal use. It is usually prepared from
the natural substance by a process involving electrical sedimentation. Light Kaolin is used to adsorb toxins in
various forms or enteritis. It must be free from gritty particles.
Tests: Light Kaolin is required to comply with the limit test for coarse particles larger than 10 microns & 3
microns in diameter.
The test for coarse particles uses Sodium pyrophosphate as a peptizing agent (to keep fine particle in colloidal
suspension) the suspension is drawn off in such a way as to leave all coarse particles below the depth of
decantation. Particles larger than that 10 or 3 microns in diameter are determined by a pipette method, which
gives a measure of the particle size distribution in terms of wt/ml of an aqueous suspension.
d. Bismuth Subcarbonate: (BiO)2CO3
Preparation: It is prepared by dissolving metallic Bi in 50% HNO3 and the solution is evaporated to a small
bulk.
Bi + HNO3 Bi(NO3)3 + NO + H2O
The solution is then added gradually with constant stirring to a cold solution of Na2CO3.The precipitated basic
carbonate is collected, washed with and equal vol. of cold water and dried at a temp. not above 60o
C. Repeated
washing of the precipitate will decompose the subcarbonate into hydroxide and therefore should be avoided.
Bismuth subcarbonate is a white, tasteless powder, is stable in pure air, but on exposure to air containing traces
of H2S, it slowly darkens.
Tests : Loss on drying, Cl-
, NO3
-
, alkalies and alkaline earths. As, SO4
-2
, Cu, Pb and Ag.

8.  Traces of Basic Nitrate is invariably found in commercial sample of Bismuth subcarbonate. Na2CO3 ,
which is often present in small proportions owing to incomplete washing and other compds.of the alkali
and alkaline earth metals are determined in a soln. from which Bi has been removed as sulphide, by
addition of the residue and weighing of the residual metallic sulphates.
 SO4
-2
is detected by precipitations as BaSO4.
 Cu by formation of the blue colour with Ammonia,
 Pb by precipitation as sulphate and Ag by precipitation as Ag2S in a soln. from which the bulk of the Bi
has been removed as sparingly soluble basic nitrate. BiONO3, Since Bi2S3 is coloured it is difficult to
apply the sulphide test for Cu, Pb.
Assay : A weighed sample is ignited to constant weight.
(BiO)2CO3 Bi2O3 + CO2
Bismuth Subcarbonate is required to yield on ignition not less than 90 % of Bi2O3
Unit D: Saline Cathartics/Purgatives
a. MgSO4.7H2O – Epsom Salt
Preparation: Epsom Salt can be prepared by neutralizing hot dil. H2SO4 with Mg, its oxide or carbonate and
evaporating the filtered solution to crystallization. (It is manufactured by the action of H2SO4 on the native
carbonate magnesite)
When dolomite is used MgSO4 goes into soln. and sparingly soluble CaSO4 is deposited.
MgCO3.CaCO3 + H2SO4 MgSO4 + CaSO4
The liquid is filtered and the filtrate is evaporated to crystallization. MgSO4 is highly soluble in water. Though
the crystals effloresce slightly in warm air, they require a temp. of over 200o
C for complete dehydration.
Tests: acidity, alkalinity, As, Fe, Pb, Zn, Cl-
and loss on drying.
 The test for Fe: If a soln. of MgSO4 is heated on a water bath, the presence of even small traces of iron
is shown by the gradual development of brownish turbidity.
 Zn is detected by precipitation as its ferrocyanide.
Assay: By titration with M/20 Sodium Edetate using NH4Cl-
NH3 buffer and mordant black as indicator. 1 ml of
M/20 Edetate is equivalent to 1 ml M/20 MgSO4.
Unit F: Essential trace elements, their compounds and applications.
 Trace elements: Copper, Cobalt, Iron, Zinc, Manganese, Chromium, Iodine, Sulphur
 Hematinics and mineral supplements: Ferous sulphate, Ferrous fumarate, Ferric ammonium citrate (Iron
and ammonium citrate), Ferrous gluconate, Iron dextran injection
a. Iodine:
Preparation: Mostly obtained from seaweeds (Chile saltpeter). Dried sea-weed is burned and the ash is
extracted with water. From the solution, sulphates and chlorides of Na & K are separated by concentration and
crystallization. The small quantities of sulphides and thiosulphates present are decomposed by addition of
H2SO4. The acid solution, which now contains the freely soluble iodides with only small proportions of
bromides and chlorides, is treated with the correct proportion of Chlorine and the precipitated iodine is collected
and purified by sublimation.
Iodine, naturally liable to contain ICl, IBr are freed by sublimation with some KI which forms KCl & KBr with
liberation of I2.
Much Iodine is obtained from the mother liquor remaining after the crystallization of NaNO3 from solutions of
Caliche. The liquor, which contains NaIO3 is treated with NaHSO3.
NaIO3 + NaHSO3 Na2SO4 + NaHSO4 + I2 +H2O
The precipitated Iodine is collected and purified by sublimation. Iodine crystallizes in almost black rhombic
prisms, with a metallic lustre. It is appreciably volatile even at ordinary temps. Melts at 114o
C but readily
undergoes sublimation at lower temps.
Properties: It is very sparingly soluble in water but is soluble in alcohol, ether, chloroform and CS2. Also
dissolves in solns. of KI and iodides. Solution of I2 in CHCl3 & CS2 are violet. Solution in water and alcohol are
reddish brown. Iodine gives with starch a deep blue colour, which disappears or warming but reappears on
cooling. This is a very characteristic and sensitive test.
Test for Cl & Br
 AgI is almost insoluble
 AgCl is freely soluble

9.  AgBr is appreciably soluble in dil. HNO3 but reprecipitated by addition of excess of dil.HNO3.
Assay: A soln. in aq. KI is slightly acidified and titrated with N/10 Na2S2O3 using starch as indicator.
Na2S2O3 + I2 Na2S4O6 + NaI
1000 ml of Na2S2O3 is equivalent to 1/10 of Iodine
b. Strong Solution of Iodine:
It contains 5.0 % w/v of I2 and 10.0 % of KI.
Assay : A 25 % v/v solution with water is prepared and the free I2 is determined in 20 ml by titration with N/10
Na2S2O3. The KI is determined in 10 ml of the diluted soln. The soln. is further diluted with water and strongly
acidified with HCl. It is titrated with M/20 KIO3. The liberated HI and HIO3 (Iodic) acids first react with
liberation of I2.
HI + HIO3 I2 + H2O
HCl+ I2 + HIO3 ICl + H2O
The titration is continued with vigorous shaking until most of the Iodine is converted to monochloride as shown
by the change in colour of the solution to pale brown. I ml of amaranth soln. is then added and the addition of
iodate is continued slowly and with constant stirring, until the red colour just changes to pale yellow. The KIO3
reacts with both KI and free I2.
KIO3 + KI + HCl KCl + ICl + H2O
KIO3 + I2 + HCl KCl + ICl + H2O
The volume of M/20 iodate used in reacting with KI is found out by subtracting from the total volume of M/20
iodate ¼ of the volume of Na2S2O3 used in the assay for free Iodine.
1000 ml of M/20 Iodate is equivalent to 1/10 of KI.
c. Weak Iodine solution:
It contains 2.5 % w/v of I2 and 2.5 % w/v of KI
A weighed quantity of Iodine is dissolved in an aqeous soln. of KI and sufficient alcohol is added to produce the
required volume.
Assay: Free Iodine is determined in 10 ml by dilution and titration with Na2S2O3. KI is determined in 10 ml
as described above.
d. Iodised Oil Fluid Injection:
This is a sterile preparation distributed in single dose containers, which is used in X-ray diagnoses.
It is made by treating the ethyl esters of the fatty acids obtained from poppy-seed oil with HI. Poppy-seed oil is
a drying oil containing a high proportion of unsaturated glycerides and the official requirement for Iodine
content (38-41%) or combined Iodine.
Tests for purity: wt/ml, acidity, chloro compounds and free Iodine.
Assay: Iodine is converted to soluble ZnI2 by boiling a weighed quantity of the injection with Zn powder and
acetic acid. After dilution and filtration the iodide is determined in the aq.. liquid by titration with M/20 KIO3 in
presence of KCN. The soln. is acidified with HCl and treated with KCN with the result that the mixture contains
HI & HCN.
ZnI2 + HCl ZnCl2 + HI
KCN + HCl KCl + HCN
The acid soln. is then titrated with M/20 KIO3. This results first in liberationof I2 which is further converted by
KIO3 to ICN. Starch is used as indicator towards the end of the titration.
KIO3 + HCl HIO3 + KCl
HIO3 + HI I2 + H2O
HIO3 + I2 + HCl ICN + H2O
KIO3 + ZnI2 + KCN + HCl ZnCl2 + KCl + ICN + H2O
1000 ml of M/20 KIO3 is equivalent to 1/10 of I.
e. FeSO4
Preparation: FeSO4 is prepared by adding a slight excess of Iron to dil.H2SO4
Fe + H2SO4 FeSO4 + H2
When efflorescence ceases the liquid is concentrated by boiling, filtered and cooled. The crystals are separated
and dried at room temp. FeSO4 forms pale green monoclinic prisms of heptahydrate. FeSO4.7H2O.
FeSO4 crystals effloresce in dry air and on exposure to moist air undergo slow oxidation becoming coated with
a brown basic ferric sulphate.
Tests for purity : acidity, As, Cu, Pb, Zn and basic sulphate.

10.  Cu is detected by means of H2S in acid solution.
 Insoluble basic ferric sulphate is detected by a turbidity in the aqeous soln.
Assay: Titration with N/10 KMnO4 in presence of dil. H2SO4
FeSO4 + H2SO4 + O Fe2(SO4)3 + H2O
1000 ml of N/10 KMnO4 is equivalent to 1/10 FeSO4
f. Dried FeSO4: Prepared by drying the crystalline salt at 40o
C . The product is a mixture of hydrates
corresponding to the formula FeSO4.2H2O. Dried FeSO4 is a grayish white powder which dissolves slowly in
water. In other respects it resembles FeSO4.
Tests : As, Cu, Pb and basic sulphate
 Dried FeSO4 is required to give with freshly boiled and cooled water and a little H2SO4 a solution which
is not more than faintly turbid.
Assay:
Titration with N/10 KMnO4 in presence of dil. H2SO4
FeSO4 + H2SO4 + O Fe2(SO4)3 + H2O
1000 ml of N/10 KMnO4 is equivalent to 1/10 FeSO4
g. Ferrous Gluconate: [CH2OH.(CHOH)4.COO]2Fe. 2H2O
Prepared by the decomposition of Barium Gluconate and FeSO4 and removal of BaSO4
Test : Acidity, As, Ba, Fe+3
, Pb, Cl-
, Oxalate, SO4
-2
, dextrose and sucrose and loss on drying.
 Ferric iron is determined by an iodometric method.
 Oxalate by precipitation as Calcium Oxalate from the residue of an ether extraction
 Dextrose and sucrose by reduction of Fehling's solution after removal of iron as Fe2S.
Assay : The compound is titrated with N/10 Cerric ammonium sulphate using 1,10-phenanthroline –ferrous
complex as indicator. In presence of iron salts the indicator change is from orange-red to pale green.
Ce+4
+ Fe+2
Ce+3
+ Fe+3
1 ml of N/10 Cerric ammonium sulphate is equivalent to 0.04822 g Ferrous Gluconate
h. Ferrous Fumarate:
Preparation: Prepared from FeSO4 and Sodium Fumarate. Ferrous Fumarate is a reddish orange-to-reddish
brown powder, only very sparingly soluble in water.
Tests: Loss on drying, SO4
-2
, As, Fe+3
& Pb.
 Ferric Iron is determined by the method used to assay Ferric Amm.Citrate.
 Lead is extracted as the dithizone-complex, the complex is then compared spectrophotometrically with a
control.
Assay : A weighed sample is dissolved in dil.HCl and any ferric iron present is reduced to ferrous by means of
SnCl2. Excess SnCl2 is removed by addition of HgCl2. A large excess of SnCl2 is avoided to prevent reduction
of HgCl2, the ppt. formed should not be excessive and should be white and not grey. To prevent any oxidation
of the chloride, phosphoric acid is now added to form a complex with the ferric iron formed in the titration. The
subsequent procedure follows that used in the assay of Ferrous Gluconate using Cerric ammonium sulphate.
1000 ml of Cerric ammonium sulphate is equivalent to 1/10 C4H2FeO4
i. Ferric Ammonium Citrate:
Iron salts of organic acids are known as 'scale preparations' which are glistening amorphous flakes or 'scales'
Prepared by evaporating the soln. to a syrup and painting in a thin layer in glass plates. The film is dried in a
dust free atmosphere.
Fe2(SO4)3 + NaOH Fe(OH)3 + Na2SO4
Fe(OH)3 is washed and stirred with enough citric acid to dissolve the whole of it. A slight excess of NH3
is added and the small quantity of undissolved Fe(OH)3 is removed by filtration. The clear reddish brown
filtrate is evaporated to syrup. The syrup is painted on glass plates and removed as flakes after drying.
Assay : Pharmacopoeial requirement is 20.5 - 22.5 % Fe
A weighed quantity is dissolved in water, acidified with H2SO4 and N/10 KMnO4 is added drop by drop to
oxidize any Ferrous Iron that may be present. It is only necessary that the pink colour persist for a few seconds.
The soln. is treated with excess of HCl & KI. The liberated HI is oxidized by the Ferric salt with liberation of I2
which after dilution is determined by titration with N/10 Na2S2O3 with starch as indicator.

11. FeCl3 + HI FeCl2 + HCl + I2
Na2S2O3 + I2 Na2S4O6 + NaI
1000 ml of N/10 Na2S2O3 is equivalent to 1/10 Fe.
Unit G: Topical agents and dermatological preparations
 Protectives: Talc, Zinc oxide, Zinc stearate, Titanium dioxide, Siicone polymer
 Antimicrobials: Potassium permanganate, Chlorinated lime, Iodine preparations, Silver nitrate,
Boric acid, Borax
a. Chlorinated Lime – Ca(OCl)Cl Bleaching Powder
Preparation: Bleaching powder is manufactured by the action of Ca (OH)2. The slaked lime, which is pure and
dry is spread in layers several inches deep in lead chambers. Cl2 is passed into the chambers until the lime is
saturated. The process is completed in 12-24 hours.
Ca(OH)2 + Cl2 Ca(OCl)Cl + H2O
Bleaching powder is a dull white powder, which slowly decomposes with loss of Cl2 on exposure to air.
Assay: Bleaching powder is required to contain not less than 30% w/w of available Chlorine. For the assay, an
aqueous suspension of the substance is treated with Acetic acid in presence of KI.
CaOCl2 + CH3COOH (CH3COO)2Ca + HOCl + HCl
HOCl H2O + Cl2
KI + Cl2 KCl + I2
The Iodine produced is titrated with N/2 Na2S2O3 using starch as indicator.
Na2S2O3 + I2 Na2S4O6 + NaI
1000 ml of Sodium thiosulphate is equivalent to 1/10 of I and therefore 1/10 of Cl.
b. Silicone Polymers: These are inert protective substances occurring in liquid form and known generally as
silicone oils. They are primarily dimethyl-silicone ethers.
One such polymer is known as Dimethicone or Simethicone and is used in ointments and creams for application
to the skin as a water repellent and protective against contact irritants. The usual concentration in these
preparations is about 30%.
Uses: Simethicone is an antifoaming agent used to reduce bloating and flatulence discomfort and pain caused
by excessive gas in GI tract.
c. KMnO4 :
Preparation: MnO2 is fused with excess of KOH in the presence of excess of air or with the addition of some
oxidizing agents such as KNO3 or KClO3
KOH + MnO2 + O K2MnO4 + H2O
The green mass of K2MnO4 is extracted with water and treated with CO2
K2MnO4 + CO2 KMnO4 + MnO2 + K2CO3
or, K2MnO4 + Cl2 KMnO4 + KCl
On a larger scale – by the electrolysis of a warm solution of K2MnO4
K2MnO4 + 2H2O KMnO4 + KOH + H2

12. Tests for Cl-
& SO4
-2
: Before carrying out the tests it is necessary to remove the purple colour of KMnO4.To
overcome the interference, the permanganate is reduced in boiling aqueous soln with 95% alcohol. MnO2
precipitated is removed by filtration.
KMnO4 + CH3CH2OH KOH + MnO2 + CH3CHO + H2O
Assay: Is performed by titration with N/10 Oxalic acid.
1 ml of N/10 Oxalic acid is equivalent to 0.003161 g of KMnO4
d. Silver Nitrate:
Preparation: Metallic Ag is dissolved in hot fairly concentrated HNO3
Ag + HNO3 AgNO3 + NO2 + H2O
The solution is evaporated to dryness and the residue is heated to expel all HNO3. The product is then
recrystallised with water.
AgNO3 forms crystalline plates, which are very soluble in water. The salt melts at 209o
C without decomposition,
but decomposes at dull red heat with evolution of Oxides of Nitrogen leaving a residue of metallic Ag. It slowly
decomposes in light, turning black and both the solid and its solution should be protected from light.
Test for purity ; Bi, Cu, Pb
Adding NH3 to the solution first produces a dark ppt. of Ag2O, which dissolves in excess of NH3. Bi & Pb cause
a white turbidity which are not soluble in excess of NH3. Cu gives a blue soln. due to formation of intensely
coloured Cu(NH3)4
+2
ion.
Assay : Ag is determined gravimetrically as AgCl. AgNO3 soln. is acidified with HNO3 before precipitation
with a slight excess of HCl. Completion of the precipitation is done in the dark because of the photosensitivity
of AgCl. The ppt. is collected in a sintered glass crucible. The ppt is dried at about 160o
C and weighed.
Another method is titration with N/10 NH4SCN using ferric ammonium sulphate as indicator.
AgNO3 + NH4SCN AgSCN + NH4NO3
1000 ml of N/10 NH4SCN is equivalent to 1/10 AgNO3
e. Boric Acid: H3BO3
Preparation:
Na2B4O7 + H2SO4 + H2O Na2SO4 + 4H3BO3
Adding a mixture of conc. H2SO4 (12ml) and water (60ml) to a boiling soln. of Borax (60g) in water (160ml).
The hot liquid is filtered, the Boric Acid is washed until free from sulphate and dried.
Boric Acid forms pearly, triclinic crystals soluble in 25 parts water and in 4 parts glycerol. The acid, in free
state or in the form of a salt can be detected by mixing the subs. with conc. H2SO4 in a porcelain dish, adding a
little alcohol and setting alight. The flame is tinged green, owing to formation of a volatile ethyl borate. Free
Boric Acid turns litmus to dull red, but does not effect methyl orange, it is a very weak acid.
Tests: As, Pb. SO4
-2
.
 The pharmacopoeia requires that 1 g Boric Acid dissolves completely in 10 ml of boiling alcohol.
Assay : A mixture of the sample and ten times its weight of mannitol in water is titrated with 1N NaOH , using
phenolphthalein as indicator.
NaOH + H3BO3 NaBO2 + H2O
The object of the mannitol is to form a mannityl boric acid which is strong enough acid to give a good end
point.
1000 ml of 1N NaOH is equivalent to 1 of Boric Acid.
f. Borax: Na2B4O7
Prepared from Colemanite (Calcium Borate) by double decomposition with Na2CO3.
Borax crystallizes as Na2B4O7.10H2O in colourless efflorescent, monoclinic prisms and is soluble in 25 parts
water and 1 part glycerol. Its aqueous soln. has an alkaline reaction.
Na2B4O7 + H2O H3BO3 + NaBO2
NaBO2 + H2O NaOH + H3BO3
When heated on a platinum wire in a Bunsen flame, borax fuses, swells, loses water and finally forms a clear
anhydrous salt. Fused borax dissolves compounds of certain metals forming characteristically coloured beads.
The colour depends on the nature of the metal and on whether the bead is heated in oxidizing or reducing part of
the flame.
Tests: As, Fe, Pb, CO3
-2
, H3BO3, Cl-
, SO4
-2
Assay: A solution of the borax is titrated with N/2 HCl with methyl red as indicator. The colour changes when
all the boric acid is set free, since boric acid has no effect on methyl red.

13. HCl + Na2B4O7 + H2O H3BO3 + NaCl
Phenolphthalein and mannitol are now added and the free boric acid is titrated as in Boric Acid.
The vol. of 1N NaOH used in the second titration should be the same as the vol. of semi-normal acid used in the
first.
1000 ml of 1N NaOH is equivalent to ¼ Na2B4O7
Unit H: Astringents: Aluminium sulphate, Alum, Zinc sulphate
The word "astringent" derives from Latin adstringere, meaning "to bind fast". Astringent is a drug that reacts
chemically with cellular proteins producing limited coagulation, which is accompanied with shrinkage of body
tissues.
Charateristics of astringents:
 Affect only the superficial layer.
 Reduce cellular permeability.
 Make the surface mechanically stronger, decrease exudation.
 Protect from external irritation.
 Possess local styptic and local antiseptic action.
 May interfere with the function of pain receptors.
 The pain relieving action is mild.
Therapeutic uses of astringents
 Used internally to check discharge of blood, serum or mucous secretions (in sore throat, diarrhea,
hemorrhage or peptic ulcers).
 Externally applied astringents, which cause mild coagulation of skin proteins, dry, harden, and protect
the skin. Cleaning the face and preventing acne breakouts.
 Stopping bleeding
 Relief from minor skin irritations like superficial cuts, allergies, insect bites, or fungal infections such as
athlete’s foot
 In bleeding piles and as antiperspirant/deodorant
 Strengthen gums and check bleeding
a. Alum: KAl (SO4)2.12H2O
Alum is potassium aluminium sulphate. It is a double salt and contains an amount of aluminium
not less than 99.5% of KAl (SO4)2.12H2O
Preparation: It is prepared by adding a concentrated solution of potassium sulphate to a hot solution
of an equimolecular proportion of aluminium sulphate. When the solution is cooled, characteristics
octahedral crystals are separated.
K2SO4 ++ 12H2O + Al2(SO4)3 KAl (SO4)2.12H2O
Properties: It occurs as colourless, transparent or granular crystals with a sweet astringent taste.
When heated slowly it melts in its water of crystallization. At 200°C, it loses its water of
crystallization and becomes anhydrous. It is soluble in water but insoluble in alcohol.
Action and Uses: It is used externally for its astringent properties. It has protein precipitation
property and hence is used in the preparation of toxoids. Astringent solution of alum containing
0.5 to 5% is useful antiseptic and commonly used for local styptic action.
Assay : Formerly, alum used to be analysed by gravimetric method. A known weight is dissolved
in water to which ammonia and ammonium chloride is added. It is heated to boiling, filtered and
precipitate washed with ammonium nitrate solution until free from chloride. The precipitate of
A1203 is dried to constant weight at 120°C and weighed.
According to BP., aluminium of alum is estimated by complexometric titration using disodium
edetate as titrant.

14. b. Zinc Sulphate : ZnSO4.7H20
It contains between 99 — 108% of ZnSO4.7H20.
Preparation: Industrially, it is prepared by heating zinc blend (zinc sulphide) in the presence of air
under specified conditions. The heated mass is dissolved in hot water, filtered and the solution concentrated
for crystallization.
ZnS + 202 ZnSO4
It is also prepared by digesting metallic zinc granules in dilute sulphuric acid. The solution is filtered and
treated with chlorine to oxidise any ferrous impurity into ferric sulphate, which is then precipitated by
hydroxide and removed. The filterate is concentrated and left for crystallization.
Zn + H2SO4 ZnSO4 + H2 T
Properties: It occurs as odourless, colourless, transparent crystals or a white crystalline
powder. It has a metallic or astringent taste. It is efflorescent in dry air. It is soluble in water
and glycerin but remains insoluble in alcohol.
Assay: Zinc sulphate is assayed by complexometric titration using disodium EDTA with
erochrome black T as an indicator. The strong ammonia- ammonium chloride buffer
maintains pH of 10 at which the complex is stable.
Zinc sulphate is also assayed by gravimetrically. Sodium carbonate converts zinc sulphate
to zinc carbonate, which gets converted further to zinc oxide by ignition. The residue is
collected, dried and weighed.
Unit I: Dental products (Dentrifices, Anticaries agent and Desensitizing agents): Calcium carbonate,
Sodium fluoride, Stannous fluoride, Zinc chloride, Zinc eugenol ointment.
Dentrifrices are the substances used with a toothbrush for the purpose of cleaning the accessible surfaces of
teeth. The term Dentifrices as derived from Dens (tooth) and fricare (to rub). Dentifrice is the French word for
toothpaste.
Types of Dentifrices
 Cosmetic Dentifrices: It must clean and polish the teeth
 Therapeutic Dentifrices: Must reduce some disease process (caries, gingivitis, calculus, sensitivity) in
mouth
Function
 It acts as an abrasive that aids in removing debris, dental plaque and stained pellicle from the teeth and
assists in the elimination and/or masking of halitosis.
 Delivers active ingredients such as fluoride or xylitol tohelp prevent tooth and gum disease (gingivitis)
 They polish teeth to provide increased light reflectanceand superior aesthetic appearance
a. Zinc Chloride : ZnCl2
It contains not less than 95% and not more than 100.5% ZnCl2.
Preparation: It is obtained by reacting metallic or granular zinc with hydrochloric acid. The solution is
evaporated to dryness.
Zn +2HCl ZnCl2 + H2
Alternately, it is obtained by treating zinc oxide or carbonate with appropriate amount of hydrochloric acid.
Properties: It is a white crystalline powder or granules, odourless and is deliquescent. It is very soluble in
water, freely soluble in alcohol and glycerine. The compound is reasonably soluble in polar organic
solvents. Aqueous solution is distinctly Acidic (pH 4.0). This is due to its hydrolysis to form hydrochloric
acid and basic zinc chloride similar to aluminium salts.
ZnC12+ H2O Zn(OH)CI + H+
+ CI-
Uses: Zinc chloride is a powerful astringent and mild antiseptic. It is also used in mouth wash and
deodorant preparations. The antiseptic action is considered to be due to its interaction of the metal with
certain microbial enzymes. The protein precipitation action also contributes to this effect.
Indications: Ulcerative gingivitis, pyorrhoeal pockets and apthous ulcers, included in several
mouthwashes and dental gels
The other uses of zinc chloride include protein precipitation, in various insulin preparations also as
desensitizer of dentin (in dental preparations). It is also used in fire proofing wood.
Assay : It is assayed by complexometric titration method using disodium edetate as titrant. An accurately
weighed amount is dissolved in water and a definite volume made. To a known volume of solution, ammonia-

15. ammonium chloride solution as buffer, eriochrome black T as indicator is added and the solution is titrated
with standard disodium edetate.
Storage : As zinc chloride is deliquescent and absorbs carbon dioxide, hence it is stored in closed
container.
b. Sodium Fluoride:
Contains not less than 98.0% of NaF, calculated with reference to the dried substance.
Preparation: It is commonly obtained by neutralizing hydrofluoric acid with sodium carbonate.
2HF + Na2 CO3 2NaF + H2 0 + CO2
Another method is the double decomposition of calcium fluoride with sodium carbonate wherein
insoluble calcium carbonate is filtered out
CaF2 + Na2 CO3 2NaF + CaCO3
Properties: It occurs as colourless, odourless crystals or as white powder. It is soluble in water but is
insoluble in alcohol. Aqueous solutions of the salt corrode ordinary glass bottles and hence the
solution should be made in distilled water and stored in dark, pyrex bottles.
On acidification of salt solution, hydrochloric acid is produced. This is weak acid and is poisonous.
Aqueous solution of salt gives alkaline reaction.
Action and Uses: Sodium fluoride because of its fluoride ion is an important agent in dental practice for
retarding or prevailing dental caries. Areas where in the drinking water lacks fluoride ions, sodium
fluoride in I ppm concentration is used. Higher levels than I ppm causes mottling of teeth.
Sodium fluoride in 2% aqueous solution is widely used topically, occasionally the solution is applied
to the surface of dry teeth periodically over several times in a year Fluoride ion enters the enamel
of teeth and becomes part of enamel structure and thus becomes effective.
Assay : It is assayed by complexomanc titration method using disodium edetate. A weighed quantity is
dissolved in water. small amount of sodium chloride and alcohol is added, contents heated to boiling
and dropwise excess lead nitrate is added with stirring. On cooling, coagulated precipitate is filtered,
residue washed with dilute alcohol and the combined filtrate and washings are titrated with disodium
edetate using xylenol orange as indicator.
Storage: It should he kept in well-closed containers.
c. Stannous Fluoride : SnF2
Preparation: Tin fluoride solution is prepared from using Tin fluoride capsules by dissolving in
water. A fresh solution (about 8%) is used in dentistry.
Properties: It is a white crystalline powder with unpleasant stringent-salty taste. It is soluble in water
but insoluble in alcohol and organic solvents. Aqueous solution of stannous fluoride deteriorates
rapidly on standing due to oxidation of stannous cation to stannic form resulting in turbidity.
Uses: Stannous fluoride is used in fluoride treatment of teeth. Because of instability of prepared
aqueous solutions, fresh solutions are prepared at the time of application. A freshly prepared 8%
solution of stannous fluoride is applied to the cleaned dry teeth. A single application is sufficient
for six to twelve months.
Fluorides help preventing tooth decay by
 By Promoting tooth remineralization: Fluoride in the saliva will adsorb onto the surface of a tooth
 where demineralization or tooth decay has occurred And this adsorbed fluoride attracts other minerals
(such as calcium ), thus helping to speed up the rate of mineralization.
 By inhibiting oral bacteria’s ability to create acids: Fluoride disrupts the bacteria s ability to‟
metabolize sugar
 By making the tooth more decay resistant: Teeth are composed of minerals, hydroxyapatite
and carbonated hydroxyapatite tooth mineral that iscreated during the remineralization process when
fluoride is presentis fluorapatite. Fluorapatite is „harder than other tooth minerals and is more resistant to‟
the damage caused by acids (demineralization)