Pharmaceutical Analytical Chemistry / PHC 213
Feb 23, 2016
Pharmaceutical Analytical
Chemistry / PHC 213
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Analytical Chemistry
is the study of the separation, identification, and quantification of the chemical components of natural and artificial materials
Analytical chemistry answer two important questions
What is it ??(Qualitative analysis)
gives an indication of the identity of the chemical species in the sample
How much is it ?? (quantitative analysis) determines the amount (concentration) of one or more of the components in the sample
Classification of Analytical Methods:
Gravimetric method
Volumetric method
Instrumental methods
Gravimetric method:
Gravimetric methods of analysis are based on the measurement of mass.
(:Volumetric method (Titration
involves the addition of a reactant to a solution being analyzed until some equivalence point is reached
Types of Titration:
Acid _ base titrationPrecipitimetric titrationComplexmetric titrationRedox(oxidation-reduction) titration
Instrumental methods : Spectrophotometry
Chromatography
Application of Analytical Chemistry :
Analytical chemistry play an important role in nearly all aspect of chemistry
Medicine IndustryEnvironmentalFood and AgricultureQuality control
Application of Analytical Chemistry: In medicine, analytical chemistry is the basis
for clinical laboratory tests which help the physicians diagnose disease
In industry, analytical chemistry provides the means of testing the raw materials for assuring the quality of finished products whose chemical composition is critical (eg. Drugs )
The nutritional value of food
determined by chemical analysis for major component such as protein and carbohydrate and trace components such as vitamins and minirals
Definition of some terms: Sample: is a material that we wish to analyze Analyte: is the substance or element in the sample whose
presence or concentration we wish to determine titrant: is a solution of known concentration which is added
(titrated) to another solution to determine the concentration of second chemical species
Titration:is a process which is performed
by slow addition of standard
solution "titrant" from a burette to a solution of the analyte until the reaction between the two is complete.
Standard Solution:
- is a solution of known concentration - prepared by dissolving a known amount of the
substance (primary standard substance)in a known volume of liquid
- They provide a reference to determine unknown concentrations
-Two types,, primary and secondary standard solution
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Standard solution
1-Must be easily obtained in very high
grade of purity and of known composition.
2-Very stable, and resists reactions with air
( non-hygroscopic )
3- It is recommended to have high equivalent weight to minimize weighing error.
4- It must react with other substances in quantitative way according to balanced chemical equations (stoichiometry)
Primary standard Secondary standard
1-The concentration of which can’t be directly calculated from the weight of the solute and volume of the solution. 2- The exact concentration is determined by:
- Titration against a primary standard solution
Examples:
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Standard solution
potassium acid phthalate, oxalic
acid, benzoic acid, sulphamic acid.
Borax, sodium carbonate.
Potassium dichromate, potassium bromate and potassium iodate.
Sodium oxalate, arsenious oxide, and potassium ferrocyanide.
Primary standard Secondary standard
Hydrochloric acid, sulphuric acid.
Sodium hydroxide, ammonia
Potassium permanganate
Acids
Bases
Oxidizing agents
Reducing agents
Volume difference between the equivalence point and the end point should be small .
This difference in volume is the titration error
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End point:
Equivalence point:
The point in a titration when a physical change occurs that is associated with the condition of chemical equivalence.
The point in a titration when the amount of added standard reagent is exactly equal to ( is chemically equivalent to) the amount of the analyte.
Detection of the end point
Indicator :a substance that indicate the presence, absence, or
concentration of another substance ,,often used in a titration to indicate the point at which the reaction is complete by means of a characteristic change, especially in color
such as: litmus paper in acid media in base media
Methods of expressing concentration of standard solutions
Molar solution: It is a solution of the substance containing one mole (gram
molecular weight) of the substance per one liter of solution.
Molarity (M) : It is the number of moles (gram molecular weight )of solute
per one liter of solution.
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I-Molarity
Some useful algebraic relationships:
M = no. moles solute V( L) No. of moles = M x V ( L ) No. of moles = wt.solute, g fwt
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M=MolarityV=volume in liter
Fwt= formula weight or molecular weight ( g)
Examples:
Example 1:Calculate the molarity of 17g Na2CO3 in 500ml of solution (fwt=106)
M= …… wtg …….. = 17 = 0.320 fwt × VL 106 × 0.5
Example 2: ( HOME WORK)Calculate the weight in grams of Na2CO3 required to prepare 250ml of 0.15M solution. (fwt=106)
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Convert 500 ml to liter by ÷1000 = 0.5 L
II. Normal solution: It is the solution that contains one gram equivalent weight
of solute per liter of solution.
Normality (N) : It is the number of equivalents (gram equivalent weight) per
liter of solution.
If the equivalent weight = formula weight
so, N = M
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II-Normality
Normality (N) = Number of equivelant weight Volume(V) in (Liter) No.of eq.wt = N x V(L)
OR \ No.of eq.wt = weight of solute (g) equivalent weight (Eq.wt)
Eq.wt = Formula weight (F.wt ) n (no. of (H+) OR (OH-) )
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N=nM
N=Normalityn = number of (H+) or (OH-)M= Molarity
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Problem??? Calculate the eq.wt for each of the following: HCl , H2SO4 , H2CO3 , H3PO4 , Ba(OH)2
*In case of Ba(OH)2 Ba(OH)2 2 OH- eqwt = fwt / 2
*In case of HCl or NaOH HCl 1 H+ eqwt = fwt / 1
NaOH 1 OH-
*In case of H3PO4
H3PO4 H2PO4- + H+
eqwt = fwt / 1
H3PO4 HPO4-2 + 2 H+
eqwt = fwt / 2
Examples:
1-How much primary standard potassium acid phthalate, KHC8H4O4, is required to prepare 499.5 ml of 0.10 N solution?(fwt = 204.23)
Weight ( g)?? =
No of eq.wt = N x V (L) Wt/ eqwt = N x V
Wt ( g) = N x V x eqwt = 0.1 x 0.4995 x 204.23
= 10 .20 g KHC8H4O4
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Convert 499.5 ml to Liter by ÷1000 = 0.4995 L
TYPES OF WATER USED:• Distilled water: is water that has many
of its impurities removed through distillation
• Deionized water : is water that has had
all minerals removed from it,as cations like sodium, calcium, iron, and copper, and anions such as chloride and sulfate, using an ion exchange process
Lab glassware and equipment
burette
Pipette:Graduated pipettes Volumetric pipettes
beaker
cylinder
funnels
Volumetric flask
Conical flask:
Glass stopper conical flask Conical flask
Glass rod
Mortar and pestle
Hot plate
electronic balance
hood
GENERAL GUIDELINES:
1- When first entering the lab , do not touch any equipment, chemicals, or other materials in the laboratory area until you are instructed to do so
2- Follow all written and verbal instructions carefully. If you do not understand a direction or part of a procedure, ASK YOUR TEACHER BEFORE PROCEEDING WITH THE ACTIVITY
3- Never work alone in the laboratory,No student may work in the laboratory without the presence of the teacher
4- Do not eat food, drink beverages, or chew gum
in the laboratory,Do not use laboratory glassware as containers for food or beverages
5- Observe good housekeeping
practices , Work areas should be kept clean at all times
7 -Labels and equipment instructions
must be read carefully before use
8 -Keep hands away from face, eyes, mouth, and body while using chemicals , Wash your hands with soap and water after performing all experiments
9-you should Know the locations and operating procedures of all safety equipment
CLOTHING:
Dress properly during a laboratory activity. Long hair must be tied back, Shoes must
completely cover the foot
HANDLING CHEMICALS:
1- All chemicals in the laboratory are to be considered dangerous. Avoid handling chemicals with fingers , Do not taste or smell any chemicals
2- Check the label on all chemical bottles twice before removing any of the contents
3- Never return unused chemicals to their original
container, and Never remove chemicals or other materials from the laboratory area
HANDLING GLASSWARE AND EQUIPMENT:
1- Never handle broken glass with your hands , Place broken glass in the sharps container
2- Examine glassware before each use
3- Never look into a container that is being heated4- hood (how can we use it in the safe way )
COURSE SYLLABUS:
Thank you