Dr. Abdul Muttaleb Jaber Professor of Analytical Chemistry

63 Pages·2014·1.06 MB·English

Dr. Abdul Muttaleb Jaber
Professor of Analytical Chemistry
Email: [email protected]
0510113 Pharmaceutical
Chemical Analysis
Textbook
Analytical Chemsitry
Gary D. Christian
6th Edition, 2004
Chapter 1
Analytical objectives or what
analytical chemists do?
What is analytical chemistry?
• Analytical chemistry is the science that deals with the chemical
characterization (qualitative and quantitative) of matter.
• Analytical chemistry is applied in many aspects of chemistry:
agricultural, clinical, environmental, forensic, manufacturing,
metallurgical, and pharmaceutical chemistry.
• The quality of manufactured products depends on proper
chemical proportions of active components, and measurement
of these components is the basis of the quality
control/assurance of products.
• Qualitative analysis deals with the identification of elements,
ions, or compounds present in a sample.
• Quantitative analysis deals with the determination of how
much of one or mo re constituents is present.
Classifying Analytical Methods
1. Wet methods of chemical analysis (Traditional or
classical methods):
• Gravimetric Methods: The analyte is precipitated by a
certain reagent. The amount of the analyte is
determined from the mass of the precipitate
• Volumetric Methods: the concentration of the analyte is
determined as a result of adding to it a measured
volume of solution containing a reagent of known
concentration to react completely with it.
Analytical Methods
2. Instrumental Methods of analysis
• Electroanalytical Methods: it involve the measurement of
voltage, current, resistance, or quantity of electrical charge.
• Spectroscopic Methods: it involves the interaction between
electromagnetic radiation and matter (analyte atoms or
molecules).
• Chromatographic methods: it is based on separating the
components of a mixture as a result of their degree of distribution
between two phases (mobile and stationary phase)
• Miscellaneous Methods: include rate of radioactive decay, heat of
reaction, rate of reaction, thermal conductivity, optical activity,
refractive index, and others
THE ANAL YTICAL PROCESS
The analytical process may be take place
according to the following sequence of events:
(1) defining the problem
(2) obtaining a representative sample
(3) preparing the sample for analysis
(4) performing necessary chemical separations
(5) performing the measurement

(6) calculating the results and presenting the
data.
An analysis involves several
steps and operations which
depend on:
•the particular problem
• your expertise
• the apparatus or
equipment available.
The analyst should be
involved in every step.

©Gary Christian,
Analytical Chemistry,
6th Ed. (Wiley)

Fig. 1.1. Steps in an analysis
Defining the problem
• Before the analyst can design an analysis
procedure, he / she must know
• what information is needed?
• what type of sample is to be analyzed
• how the sample is to be obtained
• how much of the sample is needed
• how sensitive the method must be
• how accurate and precise it must be?
• what separations may be required to eliminate
interferences.
Acquiring the Sample
• A laboratory analysis sample must be representative of the
whole so that the final result of the chemical analysis
represents the entire system
• The material to be sampled may be solid, liquid, or gas. It
may be homogeneous or heterogeneous in composition.
– In the homogeneous case, a simple "grab
sample" 
taken at random will suffice for the analysis.
– In the heterogeneous case, we may be interested in the
variation throughout the sample, in which case several
individual samples will 
be required.