SCH 121(1): INTRODUCTION TO ANALYTICAL
CHEMISTRY
Introduction
There are a host of questions concerning the composition and structure of matter that fall within the
realms of analytical chemistry.
Is there mercury in sugar?
Is there aflatoxin in maize meal flour?
Is there any iron in traditional vegetables?
How much aspirin is there in a headache tablet?
What heavy metals are there in local fish?
What is the purity and chemical structure of a newly prepared compound?
- The answers may be given by simple chemical tests or by the use of costly and complex
instrumentation.
- The techniques and methods employed and the problems encountered are so varied as to cut right
across the traditional divisions of inorganic, organic and physical chemistry as well as embracing
aspects of such areas as bio-chemistry, physics, engineering and economics.
- Analytical chemistry is therefore a subject which is broad in its scope whilst requiring a specialist
and disciplined approach.
- An enquiring and critical mind, a keen sense of observation and the ability to pay scrupulous
attention to detail are desirable characteristics in anyone seeking to become proficient in the
subject.
- However, it is becoming increasingly recognized that the role of the analytical chemist is not to be
tied to a bench using a burette and balance, but to become involved in the broader aspects of the
analytical problems which are encountered. Thus, discussions with scientific and commercial
colleagues, customers and other interested parties, together with on-site visits can greatly assist in
the choice of method and the interpretation of analytical data thereby minimizing the expenditure
of time, effort and money.
The purpose of this course is to provide a basic understanding of the principles, instrumentation and
applications of chemical analysis as it is currently practiced. Emphasis will be given to techniques
based upon their application in industry and other analytical laboratories.
The Scope of Analytical Chemistry
- Analytical chemistry has bounds which are amongst the widest of any technological discipline. An
analyst must be able to design, carry out, and interpret measurements within the context of the
fundamental technological problem with which he or she is presented.
- The selection and utilization of suitable chemical procedures requires a wide knowledge of
chemistry, whilst familiarity with and the ability to operate a varied range of instruments is
essential.
- Finally, analysts must have a sound knowledge of the statistical treatment of experimental data to
enable them to gauge the meaning and reliability of the results that they obtain.
NOTE
1
, - When an examination is restricted to the identification of one or more constituents of a sample, it
is known as qualitative analysis,
- When an examination to determine how much of a particular species is present constitutes a
quantitative analysis.
- Sometimes information concerning the spatial arrangement of atoms in a molecule or crystalline
compound is required or confirmation of the presence or position of certain organic functional
groups is sought. Such examinations are described as structural analysis
- Any species that are the subjects of either qualitative or quantitative analysis are known as
analytes.
- There is much in common between the techniques and methods used in qualitative and quantitative
analysis. In both cases, a sample is prepared for analysis by physical and chemical 'conditioning',
and then a measurement of some property related to the analyte is made. It is in the degree of
control over the relation between a measurement and the amount of analyte present that the major
difference lies.
- For a qualitative analysis it is sufficient to be able to apply a test which has a known sensitivity
limit so that negative and positive results may be seen in the right perspective.
- Where a quantitative analysis is made, however, the relation between measurement and analyte
must obey a strict and measurable proportionality; only then can the amount of analyte in the
sample be derived from the measurement.
- To maintain this proportionality it is generally essential that all reactions used in the preparation of
a sample for measurement are controlled and reproducible and that the conditions of measurement
remain constant for all similar measurements.
- A premium is also placed upon careful calibration of the methods used in a quantitative analysis.
These aspects of chemical analysis are a major pre-occupation of the analyst.
The Function of Analytical Chemistry
- Chemical analysis is an indispensable servant of modern technology whilst it partly depends on
that modern technology for its operation. The two have in fact developed hand in hand.
- From the earliest days of quantitative chemistry in the latter part of the eighteenth century,
chemical analysis has provided an important basis for chemical development. For example, the
combustion studies of La Voisier and the atomic theory proposed by Dalton had their bases in
quantitative analytical evidence.
- The transistor provides a more recent example of an invention which would have been almost
impossible to develop without sensitive and accurate chemical analysis. This example is
particularly interesting as it illustrates the synergic development that is so frequently observed in
differing fields.
- In modern technology, it is impossible to over-estimate the importance of analysis. Some of the
major areas of application include:
(a) Fundamental Research
- The first steps in unraveling the details of an unknown system frequently involve the identification
of its constituents by qualitative chemical analysis. Follow-up investigations usually require
structural information and quantitative measurements.
- This pattern appears in such diverse areas as the formulation of new drugs, the examination of
meteorites, and studies on the results of heavy ion bombardment by nuclear physicists.
(b)Product Development
2
CHEMISTRY
Introduction
There are a host of questions concerning the composition and structure of matter that fall within the
realms of analytical chemistry.
Is there mercury in sugar?
Is there aflatoxin in maize meal flour?
Is there any iron in traditional vegetables?
How much aspirin is there in a headache tablet?
What heavy metals are there in local fish?
What is the purity and chemical structure of a newly prepared compound?
- The answers may be given by simple chemical tests or by the use of costly and complex
instrumentation.
- The techniques and methods employed and the problems encountered are so varied as to cut right
across the traditional divisions of inorganic, organic and physical chemistry as well as embracing
aspects of such areas as bio-chemistry, physics, engineering and economics.
- Analytical chemistry is therefore a subject which is broad in its scope whilst requiring a specialist
and disciplined approach.
- An enquiring and critical mind, a keen sense of observation and the ability to pay scrupulous
attention to detail are desirable characteristics in anyone seeking to become proficient in the
subject.
- However, it is becoming increasingly recognized that the role of the analytical chemist is not to be
tied to a bench using a burette and balance, but to become involved in the broader aspects of the
analytical problems which are encountered. Thus, discussions with scientific and commercial
colleagues, customers and other interested parties, together with on-site visits can greatly assist in
the choice of method and the interpretation of analytical data thereby minimizing the expenditure
of time, effort and money.
The purpose of this course is to provide a basic understanding of the principles, instrumentation and
applications of chemical analysis as it is currently practiced. Emphasis will be given to techniques
based upon their application in industry and other analytical laboratories.
The Scope of Analytical Chemistry
- Analytical chemistry has bounds which are amongst the widest of any technological discipline. An
analyst must be able to design, carry out, and interpret measurements within the context of the
fundamental technological problem with which he or she is presented.
- The selection and utilization of suitable chemical procedures requires a wide knowledge of
chemistry, whilst familiarity with and the ability to operate a varied range of instruments is
essential.
- Finally, analysts must have a sound knowledge of the statistical treatment of experimental data to
enable them to gauge the meaning and reliability of the results that they obtain.
NOTE
1
, - When an examination is restricted to the identification of one or more constituents of a sample, it
is known as qualitative analysis,
- When an examination to determine how much of a particular species is present constitutes a
quantitative analysis.
- Sometimes information concerning the spatial arrangement of atoms in a molecule or crystalline
compound is required or confirmation of the presence or position of certain organic functional
groups is sought. Such examinations are described as structural analysis
- Any species that are the subjects of either qualitative or quantitative analysis are known as
analytes.
- There is much in common between the techniques and methods used in qualitative and quantitative
analysis. In both cases, a sample is prepared for analysis by physical and chemical 'conditioning',
and then a measurement of some property related to the analyte is made. It is in the degree of
control over the relation between a measurement and the amount of analyte present that the major
difference lies.
- For a qualitative analysis it is sufficient to be able to apply a test which has a known sensitivity
limit so that negative and positive results may be seen in the right perspective.
- Where a quantitative analysis is made, however, the relation between measurement and analyte
must obey a strict and measurable proportionality; only then can the amount of analyte in the
sample be derived from the measurement.
- To maintain this proportionality it is generally essential that all reactions used in the preparation of
a sample for measurement are controlled and reproducible and that the conditions of measurement
remain constant for all similar measurements.
- A premium is also placed upon careful calibration of the methods used in a quantitative analysis.
These aspects of chemical analysis are a major pre-occupation of the analyst.
The Function of Analytical Chemistry
- Chemical analysis is an indispensable servant of modern technology whilst it partly depends on
that modern technology for its operation. The two have in fact developed hand in hand.
- From the earliest days of quantitative chemistry in the latter part of the eighteenth century,
chemical analysis has provided an important basis for chemical development. For example, the
combustion studies of La Voisier and the atomic theory proposed by Dalton had their bases in
quantitative analytical evidence.
- The transistor provides a more recent example of an invention which would have been almost
impossible to develop without sensitive and accurate chemical analysis. This example is
particularly interesting as it illustrates the synergic development that is so frequently observed in
differing fields.
- In modern technology, it is impossible to over-estimate the importance of analysis. Some of the
major areas of application include:
(a) Fundamental Research
- The first steps in unraveling the details of an unknown system frequently involve the identification
of its constituents by qualitative chemical analysis. Follow-up investigations usually require
structural information and quantitative measurements.
- This pattern appears in such diverse areas as the formulation of new drugs, the examination of
meteorites, and studies on the results of heavy ion bombardment by nuclear physicists.
(b)Product Development
2
