The Art and Science of Chemical analysis

1. The Art and Science of Chemical Analysis

2. Introduction to Chemical
Analysis
• Chemical analysis includes any aspect of
the chemical characterization of a sample
material.
• Analytical Chemistry?
– “Science of Chemical Measurements”

3. Areas of Chemical Analysis and
Questions They Answer
• Quantitation:
– How much of substance X is in the sample?
• Detection:
– Does the sample contain substance X?
• Identification:
– What is the identity of the substance in the sample?
• Separation:
– How can the species of interest be separated from the
sample matrix for better quantitation and identification?

4. What do Chemical Analyst Do?
• Analyst:
• Applies known measurement techniques to
well defined compositional or
characterization questions.
• Research Analytical Chemist

5. What do Chemical Analyst Do?
• Senior Analyst:
• Develops new measurement methods on
existing principles to solve new analysis
problems.

6. What do Chemical Analyst Do?
• Research Analytical Chemist:
• Creates and /or investigates novel
techniques or principles for chemical
measurements.
• or
• Conducts fundamental studies of
chemical/physical phenomena underlying
chemical measurements.

7. What is Analytical Science?
• Analytical Chemistry provides the methods and
tools needed for insight into our material
world…for answering four basic questions about a
material sample?
• What?
• Where?
• How much?
• What arrangement, structure or form?
• Fresenius’ J. Anal. Chem. 343 (1992):812-813

8. ©Gary Christian, Analytical Chemistry, 6th Ed. (Wiley)
Qualitative analysis is what.
Quantitative analysis is how much.

9. Fig. 1.1. Steps in an analysis
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)

11. Different methods provide a range of precision, sensitivity, selectivity,
and speed capabilities.
©Gary Christian, Analytical Chemistry, 6th Ed. (Wiley)

12. The sample size dictates what measurement techniques can be used.
©Gary Christian, Analytical Chemistry, 6th Ed. (Wiley)

14. Training of Chemical Analysts
(Analytical Chemists)
• Training focuses on principles and
techniques for solving measurement
problems … but…
• Chemical analysts interface multiple
disciplines to the solution of chemical
measurement problems
Physical-, organic-, inorganic-, bio-chem-,
physics, math, biology, electronic, computers

15. Training Focuses on
• Underlying principles of chemical
measurements ( integrating all chemistry
fields, math, physics, biology, electronics,
and computers).
• Developing proficiency with quantitative
analysis laboratory procedures
• Exposure to role of chemical analysis in a
broad range of modern science.

16. Chemical Analysis Affects Many
Fields
• Physical-, Organic-, …, Chemistry:
– “Theory guides but Experiment decides”
• Biotechnology:
– Distinguishing isomers with differing
bioactivities.
– Biosenors
• Materials Science:
– High-temperature superconductors

17. Chemical Analysis Affects Many
Fields
• Manufacturing:
– Quality control of packaged foods
specifications
• Forensics:
– Chemical features for criminal evidence

18. Where Do We Begin?
• Review of Basic Tools and Operations of Analytical
Chemistry
– The Laboratory Notebook
– Analytical Balances, Volumetric Glassware
– Laboratory Safety
• Error Analysis
– Concepts
– Terminology
– Evaluation of Data
– Experimental Design
• Review of Solution Chemistry
– Units
– Concentration Calculations
– Stoichiometry
– Balanced Chemical Reactions

19. Representative Sampling
• When it is required to test the quality of a
single batch of product that has been
dispersed into several containers, it may not
be necessary to sample and test the material
from each container.
• The number of containers to be sampled is
described in the ASTM D4057 protocol,
which incorporates the following principles:

20. • Width of the product specification.
• Source and type of the material and whether
or not more than one production batch may be
represented in the lot.
• Previous experience with similar shipments,
particularly with respect to the uniformity of
quality from package to package.
• Sample from a sufficient number of the
individual packages to prepare a composite
sample that will be representative of the
entire lot or shipment

21. Select at random the individual packages to
be sampled.
The number of random packages will depend
on several practical considerations. In most
cases, the number to sample is the cube root
of the total number of packages available. See
the example in Table