physical pharmacy i-ii sem jntuk lab manual

7/23/2019 Physical pharmacy I-II sem JNTUK Lab manual

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Ajman University of Science & Technology Faculty of Pharmacy & Health Sciences

.………………….

LAB!AT!" #A$UAL F!

PH"S%AL PHA!#A"'%%

entral ommittee(e)artment of Pharmaceutics

………………….. *+++ ' *++,

1



Dear Students,

The central committee of department of pharmaceutics, Faculty of

Pharmacy and Health Sciences, is pleased to introduce to you the

Laboratory Manual of Physical Pharmacy-II !""#1#$% The manual

co&ers e'periments deal (ith the principles discussed in didacticlectures% These e'periments employ fundamental principles of physical

pharmacy re)uired to desi*n, prepare physically and chemically stable

hetero*eneous dosa*e forms and ensure their therapeutic safety and

efficacy% The central committee set this manual for all the branches to

ensure the uniformity of student outcome%

+est e*ards

entral ommitteeDepartment of pharmaceutics,

Faculty of Pharmacy and Health Sciences

#



Ta-le of ontents

Part

$o.

ontent Page

$o.

Part , Analysis of (rugs -y isi-le S)ectrosco)y /0).1,2 • Determination of the standard cur&e of potassium

perman*anate at .!" and ./"nm%

• Determination of the standard cur&e of sodium

salicylate reacted (ith ferric nitrate$ at ./" and."" nm

1"

Part * (rug sta-ility 1 solution 3inetics 2

/0).1*2 • Determination of the rate constants and half-life of the

al0aline hydrolysis of P-nitrophenyl acetate in the presence of

Tris buffer pH %. and concentration "%".$

• 2ffect of temperature and determination of the acti&ation

ener*y of the al0aline hydrolysis of P-nitro-phenyl acetate in

the presence of Tris buffer

1.

/0).142 • +uffer catalysis of the al0aline hydrolysis of

P-nitrophenyl acetate%

#!

Part 4 %nterfacial Phenomena

/0).152 • Micellar Solubili3ation by 4on-ionic Surfactants 5

/0).162 • Spreadin* oefficient and 2mulsification /1

/0).172 • Determination of The 6dsorption Parameters of

7'alic 6cid on harcoal

/8

Part 5 olloi8al 8is)ersion

/0).192 Purification of colloids 9

• preparation of hydrophobic colloids

• preparation of hydrophilic colloids

.1

/0).1:2 Properties of colloidal dispersion 9

• Determination of the diffusion coefficient for crystal

&iolet throu*h *elatin *el%• Determination of the type of char*e of a colloid

./

5



• Determination of the iso-electric point of e** albumin

/0).1;2 • Stability of colloidal dispersions

• Incompatibilities of pharmaceutical colloids

• Protecti&e action of hydrophilic colloids

.:

Part 6 Heterogeneous (osage forms <

/0).1,+2 • Dispensin* of pharmaceutical suspensions

• Preparation of the effects of &arious a*ents on the

flocculation properties of suspendin* materials%

8.

Part 7 !heology

/0).1,,2 • Measurement of &iscosity of 4e(tonian fluid by

capillary tube and Failin* Sphere%

!/

/0).1,*2 • Measurement of &iscosity of 4on-4e(tonian fluid by

otational ;iscometer%

!.

/



Part %

Analysis of (rugs -y isi-le S)ectrosco)y

.



%ntro8uction

<hen matter interacts (ith an ener*y source heat, sound, electricity, li*ht, etc%$

some of the ener*y can be absorbed, causin* the particles to be ele&ated to different

ener*y le&els% In some cases, the particles can be e'cited totally out of the ori*inal

chemical system holdin* them in place% =nder certain conditions, thou*h, the amount of

ener*y absorbed can be controlled, and information about the chemical system can beobtained% This is the case in absorption spectroscopy%

If (e monitor a beam of li*ht shinin* throu*h a sample containin* a substance that can

absorb one of the beam>s (a&elen*ths, (e can obtain a plot of the amount of li*ht

absorbed &ersus the (a&elen*th% This plot is 0no(n as an absorption spectrum, and

sho(s (hich particular (a&elen*ths of li*ht a chemical species can absorb%

6 primary use of absorption spectroscopy lies in its applicability to )uantitati&e

measurements% This is a function of ho( much li*ht is absorbed, and ho( that relates to

the amount of the absorber present in the sample% The follo(in* deri&ation presents the

basics of this relationship%

<hen (e shine a li*ht beam of a certain (a&elen*th λ$ and initial intensity I " $

throu*h an absorbin* sample contained in a spectrophotometer cell, the intensity of the

li*ht beam transmitted throu*h the sample I t $ is dependent on three factors%

•1 The first factor is (hether the sample (ill absorb li*ht at that (a&elen*th

•2 The second is the amount of sample that the li*ht must pass throu*h or,

the cell width b$%

•3 The third factor is the concentration of the absorbing species in the

8



sample solution $%

The fraction of li*ht transmitted, or transmittance T$, is defined as the follo(in*9

1$

and,

Percenta*e of li*ht transmitted ? T$ @ T A 1"" #$

(here,

I " @ initial intensity of the li*ht beam, and

I t @ transmitted intensity of the li*ht beam

The transmittance of the sample &aries lo*arithmically (ith the cell (idth and the

concentration of the absorbin* species in the follo(in* (ay9

lo* 1BT$ @ -lo* T @ proportionally constant$ b 5$

The proportionality constant depends on9

•1 The chemical nature of the indi&idual absorber%

•2 The (a&elen*th at (hich the measurements are bein* made%

•3 The units of b and %

In &isible absorption spectroscopy, b is normally measured in centimeters% If is

also measured in molBL molar concentration, M$, the proportionality constant is defined

as the molar absorptivity ε$, (hich has units of lBM-cm% If is measured in any other

units e%*%, *Bl$, the constant is simply called the absorptivity a$, (hose units (ill depend

on % =nder normal operatin* conditions, CεC or Ca are determined e'perimentally by

measurin* a standard of 0no(n concentration%

!



Factors that (etermine Transmitte8 Light %ntensity

The precedin* relationship relates the amount of li*ht transmitted throu*h the sample to

the concentration and cell (idth% <e fre)uently li0e to thin0 in terms of ho( much li*ht

is absorbed by the sample, so (e define a ne( term, absorbance 6$9

6 @ lo* 1BT$ @ -lo* T /$

Ma0in* all of the appropriate substitutions, (e *et9

6 @ ε b (hen @ molBL or M$ .$

or,

6 @ a b (hen @ *Bl or other units$ 8$

This e)uation is 0no(n as Beer=s La>, (hich sho(s the linear relationship bet(een theabsorbance and the concentration of the absorbin* species%

In chemical analysis, the following two methods can utilize Beer's Law:

1% Absolute Calculations

6bsorpti&ity or molar absorpti&ity is calculated by measurin* the absorbance of a

standard of 0no(n concentration in a cell 0no(n cell (idth% This calculated &alue is then

used to determine an un0no(n concentration of the same absorbin* species from the

absorbance measurement at that concentration%

#% or!ing Curve Analysis

The absorbance of a series of three to fi&e standard solutions are measured and

plotted on *raph paper a*ainst the concentrations of these standards% This is 0no(n as a

Beer=s La> )lot% The absorbance of an un0no(n concentration is then measured, and its

concentration is determined directly from the plot%

"his method is more commonly used than the absolute calculation,

because e#perimental error will average out over the number of standards$



Beer=s La> Plot

/0)eriment ,

• (etermination of the stan8ar8 curve of )otassium

)ermanganate at 69+ an8 65+nm.

Proce8ure <

1% Prepare 8 different dilutions of Potassium Perman*anate by usin* a "%"1?stoc0 solution ss$ as in Table 1%

:



#% Set up the (a&elen*th of spectrophotometer to ./" nm% =se distilled (ater as

a blan0%

5% inse one of the cu&ette (ith distilled (ater and fill it (ith the (ater% Place it

in the first sample compartment% inse another cu&ette (ith small portions of

the first standard solution, and fill it (ith the solution% Put the cu&ette in thesecond sample compartment% epeat the rinseBfill for the other solutions usin*

additional cells and put them in sample compartments%

/% Put the sample tray in the blan0 position% Push E6uto eroG% Then measure the

absorbance of each of your solutions%

.% Set up the (a&elen*th of spectrophotometer to .!" nm% =se distilled (ater as

a blan0% epeat steps 5-/ and list results in Tables #%

Ta-le ,< Potassium Permanganate 8ilutions using +.+,? stoc3 solution 1ss2@

their concentrations an8 the resulte8 a-sor-ance at 65+ nm.

mls of ss mls of >ater ? of 8ilution onc. of solution A-sor-ance

, , ; ,+ +.++,

* * : *+ +.++*

4 5 7 5+ +.++5

5 7 5 7+ +.++7

6 : * :+ +.++:

7 ,+ + ,++ +.+,

Ta-le *< Potassium Permanganate 8ilutions using +.+,? stoc3 solution 1ss2@

their concentrations an8 the resulte8 a-sor-ance at 69+ nm.

mls of ss mls of >ater ? of 8ilution onc. of solution A-sor-ance

, , ; ,+ +.++,

* * : *+ +.++*

4 5 7 5+ +.++5

5 7 5 7+ +.++7

6 : * :+ +.++: 7 ,+ + ,++ +.+,

1"



Analysis of !esults

Plot absorbance &%s concentration to construct +eers plot% alculate the slope of the plot

usin* the follo(in* 2)%

Slope @ 6bs# 6bs1$ B onc# onc1$ @ absorpti&ity @ a

The concentration of the un0no(n sample can be obtained by di&idin* absorbance

by the slope%

• (etermination of the stan8ar8 curve of so8ium salicylate

1reacte8 >ith ferric nitrate2 at 65+ an8 6++ nm

Proce8ure

• Prepare 8 different dilutions of sodium salicylate by usin* a "%"1?

stoc0 solution ss$ as in Table 5% Ta0e ml of each (or0in* solution and add

# ml of the ferric nitrate solution pro&ided to produce a color %

• Set up the (a&elen*th of spectrophotometer to ./" nm% =se ferric nitrate

rea*ent 1? ferric nitrate in 1? nitric acid$ as a blan0%

• inse one of the cu&ette (ith ferric nitrate rea*ent and fill it (ith the rea*ent%

Place it in the first sample compartment% inse another cu&ette (ith small

portions of the first colored standard solution, and fill it (ith the solution% Put

the cu&ette in the second sample compartment% epeat the rinseBfill for the

other solutions usin* additional cells and put them in sample compartments%

• Put the sample tray in the blan0 position% Push E6uto eroG% Then measure the

absorbance of each of your solutions%

• Set up the (a&elen*th of spectrophotometer to ."" nm% =se ferric nitrate

rea*ents as a blan0% epeat steps 5-/ and list results in Tables /%

Ta-le 4< So8ium salicylate 8ilutions using +.+,? stoc3 solution 1ss2@ their

concentrations an8 the resulte8 a-sor-ance at 65+ nm

mls of ss mls of >ater ? of 8ilution onc. of ferric com)le0 A-sor-ance

, , ; ,+ +.+++:

* * : *+ +.++,7 4 5 7 5+ +.++4*

5 7 5 7+ +.++56

11



6 : * :+ +.++75

7 ,+ + ,++ +.++:

Ta-le 5< So8ium salicylate 8ilutions using +.+,? stoc3 solution 1ss2@ their

concentrations an8 the resulte8 a-sor-ance at 6++ nm

mls of ss mls of >ater ? of 8ilution onc. of ferric com)le0 A-sor-ance

, , ; ,+ +.+++:

* * : *+ +.++,7

4 5 7 5+ +.++4*

5 7 5 7+ +.++56

6 : * :+ +.++75

7 ,+ + ,++ +.++:

Analysis of !esults

Plot absorbance &%s concentration to construct +eers plot at the t(o (a&elen*ths%

alculate the slope of the plots usin* the follo(in* 2)%

Slope @ 6bs# 6bs1$ B onc# onc1$ @ absorpti&ity @ a

The concentration of the un0no(n sample can be obtained by di&idin* absorbance by the

slope%

(etermining concentrations of un3no>n<

1% Ta0e the # ml remainin* from each test tube of the pre&ious e'periment for sodium

salicylates and add them as follo(s to *et at the end 5 test tubes9

,* C 45 C 67

#% 6dd 1 ml of Ferric 4itrate to the 5 tubes

5% Set up the Spectrophotometer at ./"nm (a&elen*th and proceed as before%

/% Measure absorbance of the samples and use the standard cur&e or its slope to calculateconcentrations%

1#



Un3no>n Theoretical

oncentration in ,+'4

A-sor-ance

,* ,.6

45 6

67 ;

First metho8• oncentration of the first mi0ture @ 6bs1 B slope

• oncentration of the secon8 mi0ture @ 6bs# B slope

• oncentration of the thir8 mi0ture @ 6bs5 B slope

Secon8 metho89

Is *raphical as sho(n on the plot itselfJ it consists on relayin* the absorbance to the

plot itself and then findin* the correspondin* concentration%

15



Part *

(rug Sta-ility 1 Solution Dinetics 2

/0)eriment *

This e'periment pro&ides an introduction to the simplest type of solution 0inetics

usually encountered% <e (ill study in this e'periment a specific reaction that is the 2ster

Hydrolysis%

-77 K H#7 77H K 7H

The ester used is9 )'nitro)henylacetate.

7

1/



47# 7 H5

In this e'periment (e (ill determine the rate constant of the al0aline hydrolysis of p-

nitrophenylacetate in the presence of Tris +uffer pH @ %. and at "%. M$%

The 0inetic parameters you (ill determine are 9

1% The obser&ed ate constant of the hydrolysis and the half life of the reaction at

different temperatures #!, 5! and /!o $%

#% The heat of acti&ation for the o&erall reaction%

5% +uffer catalysis of the al0aline hydrolysis of p% nitrophenylacete%

Theoretical consi8erations

Let 2 represent the ester % Then in the absence of buffer the rate &elocity$ of the

hydrolysis reaction o&er the entire pH ran*e can be (ritten9

& @ H E2G EHKG K < E2G K 7H

E2GE7H-G ---------------------- 1 $

<here

& 9 reaction rate H

K 9 second order rate for acid cataly3ed hydrolysis%

7H- 9 second order rate for base cataly3ed hydrolysis%

< 9 first order constant for the uncataly3ed hydrolysis%

6t &ery lo( pH only the term containin* HK (ill be important , (hile at &ery

hi*h pH only the term containin* 7H- (ill be important% 6t an intermediate pH it may

be necessary to (rite all three terms, because at least one of them (ill al(ays be

relati&ely small%

In the presence of buffer catalysis, the rate of the hydrolysis reaction o&er the entire

pH can be (ritten9

&@ H E2G EHKG K < E2G K 7H

E2GE7H-G K + E+G E2G------- # $

<here + @ second order rate constant for buffer catalysis and E+G @ buffer

concentration% onsiderin* the hi*h pH ran*e only 7H and + are important % Then the

reaction rate becomes9

& @ 7H E2GE7H-G K + E+G E2G------------------------------------- 5 $

1.



A. #easuring of the o-serve8 rate constant <

For hi*h pH and in the presence of buffer catalysis, the rate of the reaction can be

2)% 5 $ Ho(e&er, if the pH and the buffer concentration are held essentially constant

throu*hout the reaction , 2)% 5 $ becomes9

& @ 7H E7H-G K + E+G N E2G @ obs E2G---------------- / $

<here Do-s E D H H'G D B BG ''''''''''''''''''''''''''''''1 6 2

2)% / $ represents a first order reaction % This (ould be called a pseudo or apparent

first order reaction $ % The dependence of O2 on time can be (ritten9

Lo* E2B2oG @ E obsB#%5"5G t ---------------------- 8 $

<here E2o Gis the ester concentration at time 3ero and E 2 G is its concentration at time t %

4o( suppose that durin* the hydrolysis of this ester the solution 6bsorbance under*oes a

chan*e % If +eers la( is follo(ed by all absorbin* species , it can be sho(n that 9

E 2 GB E2o

G @ E6 ∝ 6t GB E6 ∝ 6t G---------------------------- ! $

(here 6 7 is the 6bsorbance at t @ " , 6t at t @ t , and 6 ∝ at t @ ∝

Thus, 2)% 8$ +ecomes 9

Lo* E6 ∝ 6t GB E6 ∝ 6t G @ - obs t --------------------- $

7r

Lo* E1""E6 ∝ 6t GB E6 ∝ GG @ Lo* 1"" - obs t

Therefore, a plot of E6 oo 6t $G 6bsorbance$ or E1""E6 ∝ 6t GB E6 ∝ GG as ?$ one

of the &ertical a'is of a semi-lo* paper &s time should *i&e a strai*ht line % The slope of

this line is e)ual to E obs B #%5"5G, (hich, therefore, permits the e&aluation of

obs%

18



B. (etermination of the Halflife of the reaction <

6 )uantity often used in the discussin* first-order reaction is the half-life, t Q ,

(hich is the time re)uired for the concentration to decrease to one-half its initial &alue %

The half-life of a first-order reaction is related to the rate constant by 2)% :$9

t Q @ E "%8:5 B obs G ------------------------------------------------------- : $

The dimension of a first-order rate constant is time-1J and the usual units are sec-1%

. (etermination of the Heat of Activation <

The temperature of the en&ironment al(ays influences the obser&ed rate constant of any reaction% This influence can be )uantitati&ely follo(ed by the use of 6rrhenius

2'pression,

@ 6 e -HR BT$

<here

@ The rate constant

@ The *as constant6 @ Pre-e'ponential coefficient

HR @ The heat of acti&ation

T @ The temperature of the en&ironment in el&in o$

2)uation 1"$ predicts that the hi*her the temperature the *reater the rate constant

and therefore the faster the rate of reaction% 7n the other hand at constant temperature To

$ the pre e'ponential coefficient, the *reater the acti&ation ener*y, the slo(er thereaction, and more rate is influenced by the *i&en temperature% 2)uation 1"$ can be

re*ulated to read9

Lo* 0 Lo* 6 HR B#%5"5T$

Therefore a plot of lo* on the &ertical a'is $ &s % 1 B To

should *i&e a strai*ht

line % The slope of this line is e)ual to -HR B #%5"5 %

1!



• (etermination of the 3inetic )arameters 1 D o-s@ t I @ H 2 of the

al3aline hy8rolysis of )'nitro)henylacetate in the )resence of Tris-uffer 1 )H E :.6 an8 +.6 #2<

/0)erimentation<

In this e'periment students (ill be di&ided into si' *roups% 2ach *roup (ill

determine the rate constant and the half-life of the al0aline hydrolysis of p-

nitrophenyl acetate in Tris buffer of pH %. and "%". M $ at one temperature% Therefore,

t(o *roups (ill study the ester hydrolysis at #!

o

, others at 5!

o

and the last t(o*roups at /!

o %

1



#aterials<

2ach *roup of students (ill be pro&ided (ith the follo(in* 9

1% <ater bath adusted to a specific temperature eitherJ #!, 5! or /!o %

#% 6 1"" ml &olumetric flas0 preheated to the temperature of your (ater bath containin*

: ml of Tris buffer solution of pH %. and "%".M of total Tris buffer%5% 6 Stop(atch%

/% 6 buc0et of ice%

.% Ten test tubes%

8% 6 .-ml pipette%

!% P-nitrophenylacetate stoc0 solution in acetonitrile$ containin* "%. m*Bml

% Spectrophotometer ##S, and t(o cu&ettes%

Proce8ure<

1% 2ach *roup should di&ide the duties bet(een themsel&es (ith the help of the T6 in

char*e

#% Set the (a&elen*th of s)ectro)hotometer **!S to 5:%.nm and chec0 its

operation usin* a blan0 solution Tris buffer at pH %55 and contains"%".M total

Tris buffer$%

5% Pipette #%" ml of ester stoc0 solution into the flas0, sha0e (ell and note the time

i%e%9, 6t @ " (hen t @ "$%

/% <ithdra( . ml from the flas0 as function of time and tabulate your data in columns

(ith headin*s as in table .$%.% Immediately after (ithdra(in* the sample, measure the 6bsorbance at ma' @

5:%. a*ainst buffer$ other(ise, place the sample in ice to stop the reaction until

you are ready to measure the 6bsorbance%

8 8% Since the laboratory period is less than the time re)uired for the

complete hydrolysis of P-nitrophenyl acetate, you are pro&ided (ith

absorbance at time infinity i%e% 6; E 1%"1. $

Ta-le 6

Tem)erature<JJJJJJJJJJ

Time 1 min 2 At 1A; At 2 ?E 1AU At 2 V ,++

A U

" " 1%"1. W

1.

1:



5"

/.

8"

!.

:"

1".

1#"

15.

1."

U 1%"1.W

#"



#1

1

10

100

0 50 100 150 200

Time (min)

P e r c e n t a g e R e m a i n i n g



Ta-le 7



A U

" " 1%"1. W

1.

5"

/.

8"

!.

:"

1".

1#"

15.

1."

U 1%"1.W

##



#5

1

10

100

0 50 100 150 200

Time (min)




Ta-le 9



A U

" " 1%"1. W

1.

5"

/.

8"

!.

:"

1".

1#"

15.

1."

U 1%"1.W

#/



#.

1

10

100

0 50 100 150 200

Time (min)




(ata analysis <

1% The data *enerated by the si' *roups (ill be posted on the blac0board%

#% 2&ery student should ta0e the si' sets of data and analy3e it as follo(s 9

a% Plot ? 6; 6t $ v.s. time for the three temperatures or plot 6; 6t $

calculate the slope and then D o-s E slo)e 0 *.4+4

b% alculate half-life t Q $ for the ester hydrolysis at three temperatures

t Q @ "%8:5 B obs $

c% Plot lo* obs

$ &%s% 1 B To $ and calculate the heat of acti&ation for the

reaction from the slop%

#8



/0)eriment 4

Solution Dinetics

• Tris -uffer catalysis of the al3aline hy8rolysis of )'nitro)henyl

acetate at )H :.6 <

Last (ee0s (e determined the 0inetic parameters for the al0aline hydrolysis of p-

nitrophenylacetae% in this e'periment (e plan to study

Tris +uffer catalysis of this reaction at #!o %

Theoretical consi8erations<

Let us consider the ester hydrolysis at pH %. and at #!o %

=nder this condition, pH and the temperature are constant and H

and <

are ne*li*ible

then the rate of ester hydrolysis can be (ritten as9

& @ 7H

E7H G- K

+

E+ G N E2G

<here

obs

@ 7H

- E7H G K

+E+ G

Terms are defined in e'periment #$$%

Therefore a plot of obs

$ &s% +uffer concentration E+G (ill yield strai*ht line (ith slope

@ +

and intercept @ 7H

E7H-G%

/0)erimentation<

<e (ill di&ide you in si' *roups %2ach *roup (ill conduct a e'periment inetics

of the al0aline hydrolysis of p-nitrophenylacetate in Tris buffer $ at #!o and at

different buffer concentrations%

#!



#aterials<

2ach *roup of students (ill be pro&ided (ith the follo(in* 9

1% <ater bath adusted by a thermostat $ to #! o %

#% 6 1"" ml &olumetric flas0 containin* : ml of Tris buffer solution of pH %. and

either "%1#. M of "%"#. M total Tris %

5% Stop-(atch %

/% 6 buc0et of ice %

.% Ten test tubes%

8% . ml pipette %

!% p-nitrophenylacetae stoc0 solution in acetonitrite $ containin* "%. m*Bml

% spectrum #" , and t(o cu&ettes%

Proce8ure <

1% Pipette # ml of p-nitrophenylacetae stoc0 solution into the 1"" ml &olumetric flas0

containin* : ml of Tris buffer solution (ith proper concentration "%"1#. or "%"#.$

are preheated to#!o %

#% <ithdra( . ml from the flas0 e&ery 1. minutes and measure the absorbance at 5:%.

nm a*ainst buffer $%

5% Tabulate your data in Table -1" %

Ta-le :

#



Buffer onc. JJJJJJJJ

Time 1 min 2 At 1A oo At 2 log 1A oo At 2

" " 1%"1. -

1.

5"

/.

8"

!.

:"

1".

1#"

15.

1."

U 1%"1.

#:



5"

1

10

100

0 50 100 150 200

Time (min)




5#

1

10

100

0 50 100 150 200

Time (min)




Ta-le ,+

Buffer onc. JJJJJJJJ

Time 1 min 2 At 1A oo At 2 log 1A oo At 2

" " 1%"1. -

1.

5"

/.

8"

!.

:"

1".

1#"

15.

1."

U 1%"1.

55



5/

1

10

100

0 50 100 150 200

Time (min)




(ata analysis <

1%The data *enerated by the si' *roups (ill be posted on the blac0board %

#%2&ery student should ta0e the si' sets of data and analy3e it as follo(s 9

a% plot lo* 6 oo 6t $ &s time for all the data *enerated

b% calculate D o-s

an8 t Q $ at each buffer concentration

c% plot obs

&s Tris conc% "%"1#.,"%"#. and "%". from e'p% 4o%# $ and calculate +

Tris catalytic constant$and 7H

$ote < ( EHKG E7H-G - 1" 1/ $

5.



58



Part 4

%nterfacial Phenomena

5!



/0)eriment 5

• #icellar Solu-iliKation

%ntro8uction <

The solubili3in* po(er of (ater surfactant solutions is of *reat importance in the

preparation of dosa*e forms containin* sparin*ly soluble dru* % The factors affectin*

micellar solubili3ation are many and their interrelationship comple'% In *eneral, the

de*ree of solubili3ation is a function of the physiochemical properties of the surfactant

and solubili3ate %

In this e'periment, the effect of surfactant structure on the solubility of

undissociated salicylic acid (ill be in&esti*ated% The surfactants used (ill be nonionic

T(een 8" polyo'yethelene #"$ sorption monostearate$ , T(een /" polyo'yethelene

#"$ sorbitan monopalmitate $% Solubility determinations (ill also be conducted in T(een8" solutions buffered at hi*her pHs to determine the effect of solute ioni3ation on

solubili3ation% 6t the conclusion of this e'periment you should be a(are of the effect of

surfactant structure and solubili3ate Ioni3ation State on solubili3ation%

/0)erimental <

A. you (ill find on the side bench saturated solutions of salicylic acid in the &arious

surfactant solutions % They are labeled (ith the name and concentration ?<B; $ of the

particular surfactant % +esides surfactant, each solution contain "%14 HL to insure that

the salicylic acid remains undissociated in solution% 2ach solution, after dilution, (ill be

assayed by the usual method usin* Trindars rea*ent %=se distilled (ater as a blan0%

T>een *+

1? >v 2

A-sor-ance oncentration

1mgml2

(ilution Solu-ility

1mgml2

"

"%.

1%"1%.

5%"

.%"

5



T>een 5+

1? >v 2


1mgml2

(ilution Solu-ility

1mgml2

"%.

1%"

1%.

5%"

.%"

T>een 7+

1? >v 2


1mgml2

(ilution Solu-ility

1mgml2

"%.

1%"

1%.

5%"

.%"

B. 6fter completin* part A , analy3e the salicylic acid saturated solutions of T(een 8"

buffered at pH 5%" and pH 5% %

pH 5%"

T>een 7+1? >v 2

A-sor-ance oncentration1mgml2

(ilution Solu-ility 1mgml2

"

"%.

1%"

1%.

5%"

.%"

5:



pH 5%

T>een 7+

1? >v 2


1mgml2

(ilution Solu-ility

1mgml2

"

"%.

1%"1%.

5%"

.%"

(ata Analysis <

1% Plot salicylic solubility vs. surfactant concentration for each surfactant%

#% Plot the ratio of total solubility to a)ueous solubility vs. surfactant concentration for each pH%

onclusion<

/"



/0)eriment 6

• S)rea8ing oefficient an8 /mulsification

%ntro8uction <

+echer has define an emulsion as a hetero*eneous system , consistin* of at least

one immiscible li)uid in the form of droplets , (hose diameter , in *eneral e'ceeds "%1 u %

Such systems possess a minimal stability (hich may be accentuated by such additi&es as

surface acti&e a*ents , finely di&ided solids , etc%

The process of emulsification in&ol&es the adsorption of an emulsifyin* surface

acti&e a*ent $ a*ent at the interface bet(een the oil and (ater phase , resultin* in a

lo(erin* of the interfacial tension e'istin* bet(een the t(o phase %

Dependin* on the nature and concentration of the emulsifier and the phase &olume ratiothe resultant emulsion may be of the 7il-in-<ater or <ater-in-7il type%

7n completin* this e'periment , each student should 9

1% eali3e the relationship bet(een spreadin* coefficient and emulsion formation %

#% +e able to test for the difference bet(een 7B< and <B7 emulsion %

5% +e able to prepare emulsions usin* the hand homo*eni3er %

/% eali3e the potential for incompatibilities (hen usin* surface acti&e a*ents in the

preparation of emulsions %

Proce8ure <

A. S)rea8ing coefficient an8 /mulsification

1% Fill t(o lar*e bea0ers (ith tap (ater , after thorou*hly cleanin* (ith soap and (ater ,

and rinsin* thorou*hly % Li*htly sprin0le some lycopodium po(der into the surface of the

(ater in both bea0ers % 6fter (aitin* for the po(der to stop spreadin*

,place a drop of mineral oil onto the surface in the center of one of the bea0ers and a dropof oleic acid in the same manner in the second bea0er %

a% describe (hat occurs in the case of 9

Mineral oil

7leic acid

/1



b% The initial spreadin* coefficients of mineral oil and oleic acid are

15%/ and #/%8, respecti&ely % Do these &alues a*ree (ith your

obser&ations W

c% (hy (as the surface of the (ater co&ered initially (ith the

lycopodium po(der W

#% 6dd /" ml of (ater and 1" ml of mineral oil to a ." ml stoppered cylinder % epeat this

(ith oleic acid in place of the mineral oil% Sha0e both cylinders &i*orously for t(o

minutes and set the cylinders do(n on the lab bench % ompare the times re)uired foreach of the systems to separate completely into t(o phases %

a% Separation times 9

Mineral oil emulsion

7leic acid emulsion

b% Ho( does the separation time compare (ith the relati&e spreadin*

coefficients W

5% Sha0e the t(o emulsions a*ain and pass them throu*h a hand homo*eni3er , Sa&e

the products until ne't (ee0 %

a% Ho( do the emulsions appear at the end of the first lab W

b% Ho( do the emulsions appear at the end of a (ee0 W

c% Dose the homo*eni3er aid in the end of a (ee0 W

/#



. (etermination of /mulsion Ty)e

1% (ilution #etho8 % Place a drop of the emulsions

homo*eni3ed $ prepared in parts +-# and +-5 of this e'periment onto a (ater surface %

If it tends to this out o&er the (ater , or if it mi'es readily (ith the (ater , the emulsion is

of the 7B< type % If on the other hand the oil phase is the e'ternal phase of the emulsionthen the emulsion does not tend to mi' or spread %

#% (ye'#etho8 % 6dd # to / drops of a 1 ? F%D% ! % ed 4o% 1

solution

(ater soluble dye $ to a portion of the emulsion % If (ater is the continuous e'ternal $

phase the color (ill spread throu*hout the emulsion % If , on the other hand , the on a

spec0led appearance %

a% 2mulsion +-# is a <B7 $ 7B< $ emulsion%

b% 2mulsion +-5 is a <B7 $ 7B<$ emulsion %

(. om)ati-ility of Surface Active Agents

Prepare 1"" ml % of 1 ? a)ueous solutions of the follo(in* surface acti&e a*ents % Store

in / o3% Prescription bottles %

a% Sodium lauryl sulfate b% +en3al0onium chloride already prepared $

c% T(een "

1% 6dd . ml % of a 1? aL# of each of the abo&e solutions % =se test tubes % <hich

surfactants could not be used to prepare emulsions containin* aL# W 2'plain%

#%Place . ml of the sodium lauryl sulfate solution and . ml of the T(een " solution in

separate test tube % To each tube , add 1 ml of the ben3al0onium chloride solution % <hich

surfactant could be used to prepare an emulsion containin*

/. Phase olume !atio

Place #. ml of a 1" ? solution of 6rlacel 5 dissol&e in mineral oil in a #." ml bea0er %

6dd (ater in . ml increments (ith repaid manual stirrin* until #. ml % of (ater has been

added %=se a *lass test tube for stirrin* the emulsion % 4ote the *radual chan*es in theapparent &iscosity % <hy does the &iscosity chan*e (ith the addition of (ater W

//



ontinue to add (ater in small increments , (ith &i*orous a*itation after each addition ,

until a total of #"" ml % of (ater has been added %Homo*eni3e and determine if the

emulsion is 7B< or <B7

F. /mulsion Sta-ility

Ta0e one of the 7B< emulsions and di&ide into /'1" ml portions and subect to the

follo(in* conditions 9

1% Heat in boilin* (ater

#% Put in an ice bath%

5% 6dd . ml of ethanol%

/% 6dd . ml of 1%" M 4al

ecord your obser&ations %

/.



/0)eriment 7

• (etermination of The A8sor)tion Parameters of 0alic Aci8

on harcoal

This e'periment (ill demonstrate the adsorption phenomena and teach us to

determine to determine the adsorption parameters%

%ntro8uction<

In *eneral, colloidal dispersions ha&e the property of adsorbin* solutes at their

surfaces% Thermodynamically, such adsorption process occurs to reduce the surface free

ener*y of the dispersion and therefore increases its stability% The de*ree of adsorption of a

solute adsorbate$ on the adsorbent, depends on . factors:

1% The chemical nature of the adsorbent and the adsorbate%

#% The specific surface area of the adsorbent%

5% The temperature of the adsorbate

/% The concentration of the adsorbate

.% The pressure of the adsorbate

6t a constant temperature, the relation bet(een the amount adsorbed and the

concentration in a limited concentration ran*e may be represented by one of three

adsorption isotherms%

These 5 adsorptions theories (ere found by9

1 Freundlich9 " E M m ED. e ,n

1 Lan*muir9 " E M m E N1"m.-.e2 1, -e2O

1

1 +runer, 2mmett, Teller @X +2T9

1

1 " E N1"m.-.02 1,'02 M ,1-',20GGO

Qhere<

' 9 (ei*ht of adsorbate in *rams, adsorbed by m *rams of the adsorbent%%

Y n 9 Freundlichs 2mpirical constants

e 9 2)uilibrium onstant

Zm 9 <ei*ht of the adsorbate in *rams, adsorbed by one *ram of the adsorbent to

form a mono layer%

+ 9 2)uilibrium constant of the adsorption process

/8



0alic Aci8 f 0alic Aci8

, 6+ + ,$

* 5+ ,+ +.:$

4 4+ *+ +.7$

5 *+ 4+ +.5$

6 ,+ 5+ +.*$

7 6 56 +.,$

5% Sha0e occasionally for 1. min and set aside for half an hour to achie&e

e)uilibrium

/% Filter and reect the first portion of the filtrate after (ashin* the recei&er

(ith it%

.% Triturate #.ml of the ali)uot filtrate in each case (ith "%.4 Sodium

Hydro'ide usin* Phenolphthalein as an indicator # drops$%8% alculate the amount adsorbed in each case and list your result in the

follo(in* table%

0alic

Aci8

onc.

#l

from

,$

0alic

ml

of H*+

to 6+ml

%nitial

onc.

1i2

/n8

Point

,$ 6+ + *.*6

+.:$ 5+ ,+ ,.:

+.7$ 4+ *+ ,.46

+.5$ *+ 4+ +.;

+.*$ ,+ 5+ +.56

+.,$ 6 56 +.**6

/



After calculations the ta-le >ill -e as follo>s<

(ata Analysis<#a3e the follo>ing )lots.

• Plot ,< " vs e

• Plot *< e" vs e

•3 Plot 4< Log " vs Log e

• The first plot Plot 1$ sho(s that the adsorption phenomena deals (ith theoccupancy at the surface and as the &acancy increases, the rate of occupancy

increases, and at the end, (hen no more &acancy is a&ailable, the rate of occupancy

(ill be e)ual to "%

• The second plot Plot #$ reflects the lineari3ed form of Lan*muir e)uation% It

(ill help us findin* the Lan*muir adsorption parameters9 Zm and b%

• The third plot Plot 5$ in fact, reflects the lineari3ed form of Freundlich

adsorption isotherm e)uation% It is useful to find the Freundlich adsorption parameters9 and n%

/Ruili-rium conc.

1e22O/.P M +.+**6 1volumeNM 6+

Amount A8sor-e8

V @ i e

Log e " E M m Log " e "

/:



Part 5

olloi8al 8is)ersion

."



/0)eriment 9

• Pre)aration an8 Purification

There are t(o main methods of preparin* a colloid9

1% Dispersion i%e% splittin* coarse a**re*ations of a substance intocolloidal units% This may be achie&ed by use of9

a% Mechanical millin* or *rindin* e%*% colloid mills%

b% Irradiation (ith ultrasonic (a&es%

c% 2lectrical dispersion methods 2lectrolytic disinte*ration $

Pepti3ation e%*% (ith sol&ents or electrolytes$%

#% ondensation Method i%e% a**re*atin* &ery small atoms, ions, and

small molecules into colloidal particles% This may be achie&ed by9a% hemical reactions%

b% Decreasin* the solubility by lo(erin* the temperature or

chan*in* the sol&ent%A. Pre)aration of olloi8s

#aterials

6rsenius o'ide, ferric chloride, sil&er nitrate, sodium chloride, sulphur,alcohol, *elatin, hydro*en sulphide, acacia, sodium carbonate, tannic acid%

,. Pre)aration of hy8ro)hilic olloi8als <

a% Preparation of 6cacia Mucila*e9

Prepare #. ml of a .? dispersion of acacia in (ater%

b% Preparation of [elatin Dispersions9

Prepare #. ml of dispersions of each of 1%"? (B& and #%.?

(B& *elatin in (ater

*. Pre)aration of hy8ro)ho-ic olloi8als <

a. Preparation of Ferric hydro'ide sol%9

Into !. ml% of boilin* distilled (ater and poured 1%# ml of

5#? Ferric chloride solution% The hydrolysis \ of the Ferric

.1



chloride occurs instantly and a deep red \ sol% of Ferric

hydro'ide forms%

-. Preparation of Sil&er chloride sol% 9

Mi' 1" ml of each of .? sil&er nitrate and 1"? sodium

chloride solution% The precipitate of sil&er chloride formed isfiltered% The residue on the filter paper may be pepti3ed by

(ashin* (ith distilled (ater to produce the re)uired colloidal sol%

c. Preparation of Sulphur sol. <

This may be prepared by pourin* a saturated solution of

sulphur in alcohol or acetone into (ater ust belo( the boilin*

point% The alcohol or acetone &apori3es lea&in* the (ater insoluble

sulphur colloidal dispersion (hen alcoholic solution of resins and balsams are poured into (ater%

•4Preparation of olloidal Sil&er sol%9

To ."" ml distilled (ater add #" ml of "%14 6*475 and 1"

ml of 1? tannic acid solution% Heat this solution to !"-"o and

slo(ly add 1" ml of 1? 4a#75 solution (ith stirrin* a Ctea-

coloredC colloidal sil&er solution results (hich has the appearanceof the sol%

B. Purification of Ferric Hy8ro0i8e Sol. By (ialysis Using ello)haneBag <

Purification is concerned essentially (ith the remo&al of e'cess

electrolytes (hich usually *et absorbed onto colloidal particles durin* their

preparation% Purification may be achie&ed by &arious methods9

a% Dialysis%

b% 2lectrodialysis%

c% =ltrafilteration%

.#



The most important of (hich is the dialysis% 2lectrolytes passes throu*h

semi permeable membrane but not the colloidal particles% Therefore placin*

ferric hydro'ide sol% in a cellophane ba* immersed in distilled (ater (ill

purify Ferric hydro'ide sol% from any adsorbed chloride ions%

Proce8ure<

1% Form a cellophane ba* on the stem of a *lass funnel%

2. Fill the ba* to 1B# of its &olume (ith Ferric hydro'ide sol%and immerse in

#." ml bea0er full of distilled (ater%

3. Test for chloride ions in the (ater of the bea0er at a series of time

inter&als%

/% han*e the (ater in the bea0er at re*ular time inter&als and find out the

time necessary for the complete remo&al of electrolyte from the sol%

/0)eriment :

• Pro)erties of colloi8al 8is)ersion

A. (etermination of the 8iffusion coefficient for crystal violet through

gelatin gel.

The diffusion coefficient D$ of a neutral particle can be determined usin*

e)uation 1, if the solution of this substance (ith a concentration , is placed

on a *el and the distance, V, of the diffused particle in the *el is determined as

a function of time t$% The diffusion measurement V$ can be done by the aid

of a standard *el (ith a concentration %

.5



t @ o 2'p -V# B/Dt$

Ln t @ Ln o - -V# B/Dt$

D is defined as the amount of solute (hich (ould diffuse across unit

area under concentration *radient of unity, in unit time, if the rate (asconstant durin* that time%

In this e'periments, the diffusion coefficient of crystal &iolet in

*elatin solution containin* "%:? sodium chloride (ill be determined%

It is assumed that the dye diffuses throu*h the (ater held by the

*el% [elatin sol% (as chosen because the crystal &iolet does not interact

or *et hold by *elatin

Proce8ure<

1% Prepare #." ml of .? *elatin in saline solution "%:? 4al $

#% Distribute the *elatin into se&en test tubes%

5% =se one tube of *elatin to prepare standard *el% (ith a concentration

of 1 in ."",""" (B( crystal &iolet in (ater this (ill be used as the

standard for the color diffusion measurements%

/% Prepare three solutions of crystal &iolet in distilled (ater containin* 1

in #"" (B(, 1 in /"" (B(, and 1 in 8"" (B( crystal &iolet in (ater%.% Place about . ml of each solution on the top of t(o *els, co&er to

pre&ent e&aporation and place in test tube rac0 at room temperature%

8% Measure accurately the distance bet(een the solutionB*el interface

and the diffused crystal &iolet that is e)ui&alent to concentration of 1 in

."",""" the standard *el prepared in step 5$% The mean of the readin*s

should be ta0en-this &alue is ' mm%

!% ecord ' &alues in Table 8 as a function of time%

1% alculate the a&era*e of D for each dye concentration as sho(n in the

Table I %

Ta-le %

Time

1hrs2M M*

M*

(E'''''''''''''''''''''

5t1logo ' log2*.4+4

./



1,*++2

QQ

1,5++2

QQ

1,7++2

QQ

1,*++2

QQ

1,5++2

QQ

1,7++2

QQ

+.6

,.+

,.6

*.+*.6Q//D

oE ,*++ >> ,5+ >> ,7+ >> crystal violet .

E ,6+++ >> crystal violet .

B. (etermination of the ty)e of the charge of a colloi8

If one end of a filter paper strip is dipped into a colored hydrosol, the

ascent of the color (ill depend on the char*e of the colloid% If the colloid has a

positi&e char*e a distinct preparation bet(een the dispersed phase and the

dispersin* medium occurs in the ascendin* portion of the sol% such a

separation does not occur if a ne*ati&ely char*ed colored sol% is used% This

phenomenon is probably due to the fact that the (etted filter paper ac)uirin* a

ne*ati&e char*e% The ne*ati&ely char*ed cellulose fibers (ill allo( ne*ati&ely

char*ed colloids to rise but it (ill attract and hold positi&ely char*ed colloids

pre&entin* the ascent of a positi&e hydrosol%

Proce8ure<

1% Prepare 1? a)ueous solution of 6maranth and a 1? a)ueous solution of

methylene blue%

#% Place !" ml of each solution in 1"" ml bea0er%

5% Into each solution place the end of a strip of filter paper holded specially by

a stand, and obser&e at different time inter&als%

/% eport your obser&ation and conclusion to your instructor%

..



. (etermination of the %soelectric )oint of /gg Al-umin

Proteins e%*% 6lbumin$ beha&e as amphoteric colloid and ioni3e

both as acids and bases% There is a definite hydro*en ion concentration at(hich there is no resultant char*e on the protein molecule and its

electrophoteric mobility is &ery small% This particular pH &alue is 0no(n as

the isoelectric point, and the solubility of protein at this point passes throu*h a

minima%

In this particular e'periment the e'tent of turbidity or precipitation

of a colloid at certain pH &alues is determined% This turbidity increased to a

ma'imum at the isoelectric point%

#aterial <

6lbumin, ethyl alcohol, Mc li&aine>s buffer solutions 6 "%# Molar

disodium phosphate and 6 "%1 Molar citric acid% "%1 M sodium hydro'ide$

Proce8ure<a. Pre)aration of /gg Al-umin Solution<

1% 6ppro'imately "%. *ram of e** albumin is placed in 1"" ml bea0er

and (etted drop (ise (ith distilled (ater%

5% 6s each drop is added it is *round into the po(der until paste is

formed%

/% This paste should be carefully thinned do(n to about ."-!" ml%

.% The solution is clarified by the addition of . ml "%1 M sodiumhydro'ide%

8% The solution is subse)uently diluted to 1"" ml% and at this sta*e

any solid matter must be filtered off%

-. /ffect of )H on /gg Al-umin<

.8



1% 6 series of ei*ht test tubes containin* buffer solution in the pH

ran*e of 5- are prepared by mi'in* Mcli&ain standard solutions 6

Y + as in the Table II %

#% 7ne milliliter of protein solution is added to each of these tubes and

mi'ed rapidly%

5% The series of test tubes should be left to stand for a fe( minutes, andthe relati&e turbidities matched at each pH &alue%

/% The pH (hich sho(s the most intense turbidity is the isoelectric

point of 2** 6lbumin%

Ta-le %%

Test

tu-e$o.

)H #L of A #L of B , ml

)rotein

-servation

1 5 #%". !%:.

# / 5%. 8%1.

5 /%. .%1. /%.

/ . .%.! /%/5

. .%. .% /%#"

8 8 8%5# 5%8! ! %#/ 1%!8

:%!5 "%#!

6@ Disod% Phosphate "%# Molar 5.%8" *BL$ 4a#HP7/%#H#7%

+@ itric acid "%1 Molar #1%"1 *BL$ citric % 1#H#7%

.!



/0)eriment ;

• Sta-ility of olloi8al (is)ersions

Lyophobic colloids ha&e been affinity or the dispersin* medium and are

not sol&ated% They are stabili3ed by a char*e ac)uired by preferential

absorption of ions% Lyophilic colloids on the other hand, are hi*hly sol&ated as

(ell as char*ed% The char*e is usually a result of ioni3ation% Their stability,

ho(e&er, stems mainly from sal&ation effects%Lyophobic colloids (ill precipitate if their electrical char*e is

neutrali3ed often remain dispersed as they sol&ated%

#aterials<

Ferric hydro'ide sol% sil&er sol%, #? acacia mucila*e, 1? *elatin sol%

at pH #% Different electrolyte concentrations as sho(n in Table :"? ethanol%

Proce8ure<

1% Triturate . ml of each of the abo&e mentioned solutions in a test tube (ith

each of the electrolyte solutions in turn% eport the appro'imate

concentration in molBL necessary for the precipitation of the colloid% Time

may be allo(ed for precipitation to ta0e place%

#% The &arious solutions may be mi'ed (ith an e)ual &olume of ethanol%

5% 2&aporate . ml of each of the abo&e solutions on a (ater bath to dryness%

2'amine the residue and try to redisperse it by the *radual

addition of . ml of (ater%

.



nly hy8ro)hilic colloi8s .

• Some %ncom)ati-ilities of Pharmaceutical olloi8s

Sensiti3ation in colloidal systems may result from any of the factors

(hich cause a decrease in stability of the colloid% Thus electrolytes of opposite

char*e may precipitate lyophobic colloids% Dehydration by alcohol or too hi*h

salt concentrations may lead to instabilities in hydrophilic sols% 2&en

protecti&e colloids in concentrations belo( that (hich may protect can cause

precipitation in colloidal systems%

#aterials <

Dil% Hl, [elatin Pharma*el 6 Y Pharma*el +$, 6rsenius sulphide sol%

Ferric

hydro'ide sol%, Sil&er sol%

Proce8ure<

1% To . ml of a #? mucila*e of acacia add . ml of dil% Hl and report your

obser&ation%

#% To . ml of a #? mucila*e of acacia dd 1 ml of Ferric chloride T%S%

ecord your obser&ation%

5% To 5 ml of a #? mucila*e of acacia add . ml of each of 1? Pharma*el 6

solution lime treated *elatin, I%2%P% /%! - .$ and 1? Pharma*el + solution,

acid treated *elatin, I%2%P% !-:$% ecord your obser&ation%/% Mi' . ml of each sil&er sol%, and Ferric hydro'ide sol% ecord your

8"



turbid and &isually identical (ith the solution in test tube 4o% ! i%e% tube (ith

the ma'imum )uantity of protecti&e colloid%

!/SULTS

=sin* starch as a protecti&e colloids

Test tu-e

$o.

Sol. 1ml2 Starch sol.

1ml2

So8ium

chlori8e

sol.1ml2

-servation after a

minimum )erio8 of *5

hours.

1 . " 1

# . 1 1

5 . # 1

/ . 5 1

. . / 1

8 . . 1

! . 81

. 8 "

=sin* 6cacia mucila*e as a protecti&e colloids

Test tu-e

$o.

Sol. 1ml2 Acacia

mucilage 1ml2

So8ium

chlori8e

sol.1ml2

-servation after a


hours.

1 . " 1

# . 1 15 . # 1

/ . 5 1

. . / 1

8 . . 1

! . 8 1

. 8 "

=sin* [elatin sol% as a protecti&e colloids

Test tu-e

$o.

Sol. 1ml2 elatin sol.

1ml2

So8ium

chlori8e

-servation after a


8#



sol.1ml2 hours.

1 . " 1

# . 1 1

5 . # 1

/ . 5 1

. . / 1

8 . . 1

! . 8 1

. 8 "

85



+% Phenacetin Sus)ension

'

Phenacetin

[lycerin

Methyl cellulose 6romatic eli'ir

m%f%t% , Mist % mette dim

si* % Fl to be ta0en e&ery / hours for pain %

alculations an8 Proce8ure <

1% alculate the metric e)ui&alents and prepare half the amount %#% Phenacetin is a sparin*ly soluble po(der so it is prepared as suspension usin* a

dispersion stabili3er%

5% Methyl cellulose is used as dispersion stabili3er and is &ery often used in the form of

mucila*e in the prescription compoundin* % So it can be handled by 9

a% mi'in* the methyl cellulose thorou*hly (ith 1B5 of the re)uired amount of

(ater as hot (ater " to :" o $

b% 6fter complete dispersion cool and immerse in a bea0er contains crushed ice%

c% 6dd the remainder of (ater as cold (ater drop by drop (ith continuous stirrin*

till a clear *el is obtained %

/% Phenacetin po(der is (ei*hed and triturated thorou*hly in mortar into fine po(der %

.% 6dd Methyl cellulose mucila*e *radually (ith trituration %

8% 6dd aromatic eli'ir and complete the &olume %

88



• (etermination of the effect of various agents on the Flocculation

)ro)erties of sus)en8e8 materials <

%ntro8uction <

6 pharmaceutical suspension may be defined as a coarse dispersion containin*

finely di&ided insoluble material suspended in a li)uid medium or a&ailable in dry form

to be distributed in the li)uid (hen desired % <e are only concerned (ith the former in

the present e'ercise%

For a suspension to be acceptable it must be composed of small uniformly si3ed

particles (hich do not settle rapidly% Those particles that do not settle should not pac0

into a hard ca0e but should be redispersed completely and uniformly (ith the minimum

of a*itation% In addition, the suspension should not be so &iscous that it does not pourfreely from a bottle%

Deflocculated particles in suspension settle slo(ly but the sediment, (hich is

ultimately, formed pac0s closely in the bottom of the &essel% The result is a ca0e, (hich is

difficult to redisperse% onse)uently, it is more desirable to prepare a flocculated

dispersion% The floccules produced are lar*e in comparison (ith the indi&idual particles

and hence settle rapidly% Ho(e&er, the floccules form a loose, open scaffold-li0e

structure, (hich is easily dispersed (ith the minimum of a*itation% The theory behind this

approach has been co&ered in lecture% The main purpose of this e'periment is to

determine the effect of &arious a*ents on the flocculation properties of suspended

materials%

Proce8ure<

This e'periment (ill re)uire t(o- lab periods% Durin* the first session , you (ill

prepare the &arious systems described belo( and ma0e initial measurements and

obser&ations % In t(o (ee0s , you (ill accomplish the second phase of the (or0 by

ma0in* final measurements and compilin* the results % The follo(in* are pro&ided

Solution A Surfactant$ 6erosol "%! 1%8! *%

Distilled (ater to 1 L %

Solution B cationic flocculatin* a*ent$

6LL5, 8H#7 "%:. *%

Distilled (ater to 1"" ml%

Solution anionic flocculatin* a*ent$

H#P7/ #%" *%Distilled (ater to 1"" ml%

Solution ( suspendin* a*ent$

8!



System * < Prepare the follo(in* 9

Solution 6 1%" ml

Sulfametha3ine "% *

Distilled (ater to #"%" ml

Place Sulfametha3ine in a test tube , add solution 6 and in&ert se&eral times % 6dd

(ater to #" ml% Then sha0e (ell%

System 4 < Prepare the follo(in* 9

Solution 6 1%" ml

Sulfametha3ine "% *

Solution + #%" ml

Place Sulfametha3ine in a test tube , add solution 6 and in&ert se&eral times % 6dd

Solution + then sha0e (ell% eport your obser&ations%

System 5 < Prepare the follo(in* 9Solution 6 1/%" ml

Sulfametha3ine "% *

Solution + #%" ml

Solution 2 /%" ml

Place Sulfametha3ine in a test tube , add solution 6 and in&ert se&eral times % Then add #

ml of Solution + , cap and sha0e % Finally add /%" ml of Solution 2 and sha0e (ell %

System 6< To 1%8 * of bismuth subnitrate in a test tube add (ater to #" ml % Sha0e, sa&e

for # (ee0s and obser&e % eport your findin*s


Solution #%" ml

+ismuth subnitrate 1%8 *

Distilled (ater to #"%" ml

Place bismuth subnitrate in a test tube , add (ater , sha0e and then add solution % Sha0e

(ell , label and 0eep for # (ee0s%


Solution D 1%" ml

Solution #%" ml

+ismuth subnitrate 1%8 *

6dd solution D to +ismuth subnitrate in a test tube , sha0e , and add solution % Sha0e

and obser&e product % Sa&e for # (ee0s and then record your obser&ations%

System : < Prepare the follo(in* 9

Solution 2 1%" ml

Solution #%" ml

+ismuth subnitrate 1%8 *Prepare as in R ! abo&e %

8:



TABL/ %%

%tem (escri)tion /0)lanation

1

#

5

/

.

8

!

!"



Part 7

!heology

!5



/0)eriment ,,

• #easurement of viscosity using an st>al8 iscometer

a$ Determine the flo( time of the li)uid of 0no(n &iscosity as (ater η @ 1 c p $

b$ Determine the flo( rate Time$ of the li)uid of un0no(n &iscosity at the same

temperature%

c$ alculate the &iscosity inematics$ of the un0no(n li)uid usin* the follo(in*

formula%

η1 B η# @ t1 B t#

<here η1 and t1 are the &iscosity and time of flo( of the un0no(n fluid andη# and t# are the &iscosity of (ater 1 c p$ and time of flo( respecti&ely%

Proce8ure<

1% lean and dry the &iscometer%

#% Fill by means of arm h*$ so that the le&el in this arm stand is (ithin "%#mm of the

mar0 *$ (hen the tube is clamped &ertically%

5% +y means of a rubber tube suc0 the li)uid to about 1 cm abo&e mar0 b$%

/% 4ote the time of flo( bac0 throu*h the tube bet(een the mar0s b$ and c$%

.% Ta0e three readin* and find the a&era*e%

8% alculate the 0inematics &iscosity of the li)uid of un0no(n &iscosity usin* the abo&e

e)uation%

!/



/0)eriment ,*

• Tem)erature 8e)en8ency of viscosity

The &iscosity of a li)uid is in&ersely proportional to the temperature of this li)uid%This relationship is )uantitati&ely e'pressed by the modified 6rrhenius e)uations%

Lo* η @ lo* 6 2&B#%5"5 %1BT

Firstly, Study the &iscosity chan*e of 1? *elatin solution by temperature% Secondly,

determination of the e)uations constants 6 and 2& form the constructed *raph%

Proce8ure<Determine the dynamic &iscosity of the *elatin solution #? usin* 7st(ald &iscometer at

#.°, 5.° , /.° %

Tabulate your results, lo*η, T °$ and 1BT and plot lo*η a*ainst 1BT% alculate the

&alues of 6 and 2& form the intercept of the y- a'is and slope of the strai*ht line,

respecti&ely%

onclusion<

no(in* the onstants 6 and 2& for a particular system enablesPrediction of &iscosity &alues at any desired temperature (ithout

repeatin* the e'perimental (or0%

physical pharmacy i-ii sem jntuk lab manual

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