School of Pharmacy

PHYSICAL PHARMACY

LABORATORY MANUAL

SCHOOL OF PHARMACY University of Nizwa

Dr.M.Balamurugan Asst.Professor in Pharmaceutics

TABLE OF CONTENTS

Page. Sign S.No Date Name of the Experiment No 01 Determination of viscosity of the given sample by Ostwald’s viscometer 02 Effect on the concentration of the viscosity of the liquid (by using Ostwald’s viscometer) 03 Determination of Solubility by Gravimetric Method 04 Determination of Surface tension by Drop Number Method 05 Determination of Surface tension by Drop weight Method 06 Determination of Adsorption Isotherm 07 Determination of HLB Value of Surfactant 08 Determination of Critical Micellar Concentration of given surfactants using stalagmometer 09 Determination of the Stability of Suspensions 10 Effect of temperature on drug solubility Ex. No: 1 Determination of viscosity of the given sample by Ostwald’s viscometer

Aim: To determine the coefficient of viscosity of the given sample liquid with he help of Ostwald’s viscometer.

Requirements: Ostwald’s viscometer, stop clock, rubber tube, pipette, specific gravity bottle distilled water, liquid sample.

Principle: The time of flow of liquid for a given capillary is directly proportional to the viscosity and inversely proportional to the driving force. Viscosity can be calculated by using formula

η1= ------× η2

η1= viscosity of the sample

η2 = viscosity of the water (at 25˚C 0.8904)

ρ1 = Density of the sample

ρ2 = Density of the water (at 25˚C 0.997g/cc) t1 = flow time in second for sample t2 = flow time in second for water Figure shows the Ostwalds Viscometer

The absolute viscosity and coefficient viscosity can be determined by measuring t1 and t2, ρ1 and ρ2 and knowing the viscosity of the standard liquid. The Kinematic viscosity is defined as absolute viscosity divided by the density of liquid at a definite temperature. Kinematic viscosity = η/ ρ.

The relative viscosity can be calculated by using the formula = η1/ η2 Procedure:

 Clean the viscometer thoroughly with a mixture of warm chromic acid and then rinse it with distilled water.  The liquid whose viscosity is to be determined is delivered from a pipette in to the limb with bulb E. The quantity of liquid should be such that, when it is sucked through the tube in the next limb, the upper level stands above the A mark and lower level stands in the other limb at the bottom of bulb E.  First, suck distilled water until its upper meniscus in above A mark and then allow it to flow down. Start the stop clock when it reaches B mark. Note down the flow time in seconds in the tabular column.  Repeat this procedure till you get agreement values.  Clean the viscometer again and take equal volume of the liquid (given) and determine the flow time in seconds as above.  Determine the density of the liquid with a specific gravity bottle and calculate viscosity.

S.No Liquid Flow time in T mean “ Density g/cc seconds Seconds” 01 Distilled water 02 Sample

Calculation: To determine the density: Weight of the empty specific gravity bottle (W1) = Weight of the empty specific gravity bottle + Water (W2) = Weight of the empty specific gravity bottle + Sample (W3) = Weight of the Water (W2-W1) = Weight of the Sample Density of the sample = ------× Density of Water Weight of the Water

Result: The coefficient of the viscosity of the given liquid = ------centipoises. Ex. No: 2 Effect on the concentration of the viscosity of the liquid

(by using Ostwald’s viscometer)

Prepare 5%, 10%, 15% and 20%. v/v solution of glycerin in water. Find out the relative viscosities of these solutions with respect to water using Ostwald’s viscometer. Prepare a graph by plotting the different concentrations on x-axis against the corresponding relative viscosities on y axis. Observe the graph and report the effect of concentrations on viscosity.

Procedure: As same as the previous experiment.

Results: Ex. No: 3 Determination of Solubility by Gravimetric Method

Aim: To determine the solubility of the given drug by Gravimetric Method.

Requirements: Beaker, Glass rod, Funnel, Pipette, China dish, Sodium chloride, Water.

Procedure:

 About 100ml of water is taken in a beaker and add sodium chloride to it.  Dissolve it little by little by continuous stirring until the portions of salt remain un-dissolved.  After ensuring that the saturated solution is formed, the solution is filtered through the filter paper in to a clean dry vessel.  Pipette out 10ml of this solution in a china dish and evaporate the solution by heating over the flame until the residue will form.  The residue will be cooled at room temperature. Finally, the weight of the residue was calculated using formula. Residue weight Solubility of the residue =------ҳ 100 10 Calculation: Weight of the empty china dish = Weight of the china dish + sample = Weight of the residue =

Result: The solubility of the given drug by Gravimetric Method was found to be= Ex. No: 4 Determination of Surface tension by Drop Number Method

Aim: To determine the Surface tension of the given sample by Drop Number method.

Requirements: Stalagmometer, Water, Sample, Specific Gravity Bottle.

Procedure:  Stalagmometer is cleaned thoroughly with distilled water and then rinsed with a small amount of acetone and is dried. Clean rubber tubing is attached with a screw clip at the top of the stalagmometer to regulate the flow of the liquid.

 The flattened end of stalagmometer is dipped in a reference liquid (water) and is placed in a cleaned beaker.

 Liquid is sucked through the rubber tubing until the level rises above the mark A.

 The screw clip is closed tightly taking care that the liquid meniscus does not fall below the mark A.

 The Stalagmometer is fixed in a stand and the screw clip is loosened carefully allowing the liquid to run down slowly (10-15 drops/min)

 The number of drops formed is counted from a volume of a liquid between the marks A and B.

 The determination is repeated at least thrice.

 The stalagmometer is fitted with the test liquid (carbon tetrachloride) and the number of drops formed is determined from the fixed volume of liquid between the two marks as described above. The surface tension is calculated using the formula

η2ρ1

γ2= ------× γ1

η1ρ2

γ1= Surface tension of water at 30˚C is 71.18 dynes/cm

γ2= Surface tension of carbon tetrachloride

η1= Number of drops of carbon tetrachloride

η2= Number of drops of water

ρ1 = Density of the carbon tetrachloride

ρ2 = Density of the water (at 25˚C 0.997g/cc)

The density of the carbon tetrachloride is determined by the formula

(W3-W1)

ρ1= ------× ρ2

(W2-W1) Here

W1= Weight of the empty Pyknometer in gms

W2= Weight of the Pyknometer+water

ρ1= Density of carbon tetrachloride

ρ2= Density of Water (standard value) Observation:

Liquid Number Of Average Density Surface Drops gms/mL tension 1 2 3 dynes/cm Water Carbon tetra chloride

Result: Surface tension of the Carbon tetrachloride = ------dynes/cm

Density of the Carbon tetrachloride = ------gm/ml Ex. No: 5 Determination of Surface tension by Drop weight Method

Aim: To determine the Surface tension of the given sample by Drop weight method.

Requirements: Stalagmometer, Water, Sample, Specific Gravity Bottle.

Procedure:  Stalagmometer is cleaned thoroughly with distilled water and then rinsed with a small amount of acetone and is dried. Clean rubber tubing is attached with a screw clip at the top of the stalagmometer to regulate the flow of the liquid.  The flattened end of stalagmometer is dipped in a reference liquid (water) and is placed in a cleaned beaker.

 Liquid is sucked through the rubber tubing until the level rises above the mark A.

 The screw clip is closed tightly taking care that the liquid meniscus does not fall below the mark A.

 The Stalagmometer is fixed in a stand and the screw clip is loosened carefully allowing the liquid to run down slowly (10-15 drops/min).

 About 20 drops of water is collected in the weighing bottle and the weight of the bottle is already noted.

 The difference in weight between the empty weighing bottle and the weighing bottle with water is calculated.

 The procedure is repeated with given sample whose surface tension is to be determined.

Surface tension is calculated using the formula γ = m1/m2 × γw Where γ = surface tension of the given sample m1/m2 = weight of the one drop water and sample respectively γ = surface tension of water

Result: The surface tension of the given sample by drop weight method was found to be ------. Ex. No: 6 Determination of Adsorption Isotherm

Aim: (i) To study the adsorption pattern of a drug on an adsorbate from an aqueous solution. (ii) Evaluation of constants ‘b’ and ‘Ym’ of Langmuir equation. (iii) Evaluation of constants ‘k’ and ‘n’ of Freundlich equation.

Requirements: Wide-mouthed bottle, Oxalic acid, Activated charcoal, Potassium permanganate, Conc. Sulphuric acid, Burette.

Procedure: 3gms of activated charcoal is accurately weighed and placed in a clean dry bottle with stopper. 10ml of 0.5N oxalic acid is also added. 40 ml of water is added to this so that the total volume becomes 50ml. Then the bottle is shaken gently in a horizontal manner so that the activated charcoal gets evenly mixed with the solution in the bottle. The bottle is kept aside for 6-16hours. The contents are filtered into a clean conical flask. 25ml of the solution from this is taken and 5ml of Conc. Sulphuric acid is

added. This mixture is heated 75˚C and titrated against 0.2N KMnO4. The same procedure is repeated for other values given in the tabulation.

Given values: S.No Amount of 0.5N Amount of Water Amount of Activated Oxalic acid ‘ml’ added ‘ml’ charcoal ‘m’ gms 01. 10 40 3 02. 20 30 3 03. 30 20 3 04. 40 10 3 05. 50 0 3 Observatuions: S.N Normality of Concentration of Normality Equilibrium Log Y=x/m = Log C Titre value o oxalic acid oxalic acid of oxalic concentration of oxalic C A-C/m x/m x/m = ‘ml’ ‘Initial’ mg/100ml ‘ acid ‘Final’ acid mg/100ml C/y Initial’ ‘A’ Finaal ‘C’ 01. 02. 03. 04. 05.

LANGMUIR EQUATION:

c/y = C/ym + 1/bym where C= Equilibrium constant in mg of oxalic acid per 100ml of solution. Y = Amount of oxalic acid adsorbed per gram of activated charcoal (i.e) (A-C)/m X= amount of oxalic acid adsorbed i.e. (A-C) Graph: X axis= Concentration ‘C’ Y axis = C/Y Model Graph: Slope = dy/dx Intercept = b

Slope ‘Ym’ is the amount of oxalic acid absorbed per gram of activated charcoal when o mono- molecular layer is completed. FREUNDLICH EQUATION:

Log x/m = Log K+ 1/n log C Graph: X axis= log ‘C’ Y axis = log x/m Model Graph:

Model Calculations: 1. Normality of oxalic acid: Initial

V1N1 = V2N2

Where V1 = volume of oxalic acid

N1 = Normality of oxalic acid

V2 = total volume

N2 = Final normality of oxalic acid Ex. No: 7 Determination of HLB Value of Surfactant

Aim; To determine the HLB Value of given Surfactant Tween 80.

Requirements: Tween 80, reflux condenser, 0.5N Hcl, 0.5N alcoholic potash solution.

Procedure: 2 grams of the substance is accurately weighed and placed in a 250ml flask and 25ml of 0.5N alcoholic potash solution is added to it. The flask is then attached to a reflux condenser and boiled in a water bath for 1 hour. The contents are shaken once in every 10minutes during the ½ hour of refluxing. It is then cooled. One drop of phenolphthalein is added to it and is titrated against 0.5N Hcl. The difference between the “Initial” and “Final” burette readings give the volume of Hcl ‘a’ in ml. the experiment is repeated without the sample substance and the volume of Hcl ‘b’ in ml in noted. The Saponification value is calculated using the given formula (b-a)× 0.02802× 1000 Saponification value ‘S’ = ------W Where b= volume of Hcl ml: ‘Blank’ a= volume of Hcl ml: ‘Sample’ W= weight of the substance

HLB value = 20[1-S/A] Where S= Saponifcation value A= Acid value of Tween80 (190)

Observations: Initial weight of the substance= Final weight of the substance= Weight of the sample= Initial weight - Final weight= Burette S.No Contents of the flask reading Volume of Hcl Indicator Initial Final ‘ml’ ml ml 01. Sample (substance + a alcoholic potash) 02. Blank (alcoholic potash) b

Model calculation: (b-a)× 0.02802× 1000 1. Saponification value ‘S’ = ------W b= ------ml a= ------ml W= ------gms S = ------HLB = 20 [1-S/A] S = ------A = Acid value of Tween 80 = 190 = 20[1- /190] = ------Result: The HLB Value of TWEEN 80 =------Ex. No: 8 Determination of Critical Micellar Concentration of given surfactants using stalagmometer

Aim; To determine the Critical Micellar Concentration of given surfactants using stalagmometer.

Requirements: Surfactants, Stalagmometer, Distilled water

Procedure: Preparation of different concentrations of Surfactants Prepare 2% of stock solution of Tween-80 by dissolving 2gms of the same in 100ml of Distilled water. Prepare 0%, 0.02%, 0.04%, 0.08%, 0.1%, 0.2%, 0.3%, by taking 1ml, 2ml, 3ml, 4ml, 5ml, 10ml, 15ml of stock solution and makeup to 100ml with distilled water in a standard flask. The surface tension of the solution is determined using stalagmometer

γ2 = η1ρ1 / η2ρ2 × γ1

γ1 = surface tension of water at 30˚ C 71.18 dynes/cm (known value)

γ2 = surface tension of surfactant

ρ1 = density of surfactant

ρ2 = density of water at 30˚ C 0.9996gms/cc (known value)

η1 = number of drops of surfactant

η1 = number of drops of water

Plot a graph between the concentrations of surfactants in X-axis VS Surface tension in Y- axis.

Result: The critical micellar concentration of Tween 80 is ------%. Observation: S.No Vol. of 2% Vol. of distilled Conc. Of No of drops Average Density gm/ml Surface stock solution water (ml) surfactant tension 1 2 3 (ml) Tween (%) dynes/cm 1 0 100 0 0.9956 71.8 2 1 99 0.02 3 2 98 0.04 4 3 97 0.06 5 4 96 0.08 6 5 95 .1 7 10 90 .2 8 15 85 .3 Ex. No: 9 Determination of the Stability of Suspensions

Aim: To evaluate the physical stability of suspensions.

Requirements: calamine (zinc carbonate), 0.5% Acacia 500mg, 0.5% Tragacanth 500mg, 0.5% Sodium carboxy methyl cellulose 500mg, water. Principle: physical stability of the suspension is evaluated by keeping a measured volume of the suspension in a graduated cylinder in an undisturbed state for a certain period of time and notes the volumes of the sediment, which is expressed as ultimate height (Hu). This, in relation to the initial volume of the suspension (Ho), is expressed as sedimentation ratio. It should, however, be noted that sedimentation ratio (Hu/ Ho) is dependent on time and it is likely to vary at different periods of time. The sedimentation ratios at different at different periods of time can be plotted against time abscissa to give a curve that indicates the sedimentation pattern on storage. If the curve is horizontal to time axis it indicates a better suspension. However, if it steeps down it indicates a poor formulation. Procedure: different formulations are prepared by mixing calamine 5g with the suspending agents and made up to 100ml by adding distilled water. Each preparation is placed in graduated cylinders. The control is also taken in a graduated cylinder. All the cylinders are shaken simultaneously and set aside. The heights of the sediments are noted after 5,10,20,30,40,60,75, and 90 minutes. Graph with time in minutes in X- axis and sedimentation volume in Y-axis is plotted. There is no sedimentation in an ideal suspension. A stable preparation sediments slowly and redistributes immediately after shaking. Formulation Drug Suspending agent Water calamine Formulation-I 5g 0.5% Acacia 500mg 100ml Formulation-II 5g 0.5%Tragacanth 500mg 100ml Formulation-III 5g 0.5% Sodium carboxy methyl cellulose 500mg 100ml Control 5g 100ml

Observation: Initial volume of suspension Ho = 100ml Time Control calamine Acacia Tragacanth CMC in Hu Hu/Ho Hu Hu/Ho Hu Hu/Ho Hu Hu/Ho min 0

Result: ------is found to be the most stable suspending agent which sediments the suspension slower than the control. Ex. No: 10 Effect of temperature on drug solubility

Aim: To determine the effect of temperature on drug solubility.

Requirements: Boric acid, phenolphthalein, sodium hydroxide, beaker, conical flask, burette, pipette and water.

Procedure: Approximately weighed 8gms of boric acid is dissolved in 70ml of water taken in a beaker. Heat the solution to the 70˚ C and immediately pipette out 5ml of the same and transferred to a clean conical flask containing a mixture of 15ml glycerol and 10ml of water, titrate this mixture against 0.5N sodium hydroxide at various temperature as 60˚ C, 50˚ C, 40˚ C, and 30˚ C from the volume of 0.5N sodium hydroxide. The amount of boric acid is calculated which is present in 5ml sample. A graph is plotted by taking temperature on X-axis and amount of boric acid on Y-axis.

Result: The amount of boric acid in the given sample is found to be At 70˚ C = At 60˚ C = At 50˚ C = At 40˚ C = At 30˚ C = Calculations:

S.No Temperature Contents of Burette reading Volume Indicator and the flask of NaoH End point Initial Final

70˚ C 5ml Boric acid Phenolphthalein 60˚ C solution + 15ml & 50˚ C 40˚ C glycerin + Appearance of 30˚ C 10ml water pale pink color