1. CHEMISTRY 59-320 ANALYTICAL CHEMISTRY Fall - 2012
Lecture 1

2. What is Analytical Chemistry?
It is the Science of Chemical Measurements
providing methods and tools needed for gaining insight into our material world.
There are four basic questions about a material sample?
What? (What is the identity of the substance in the sample?)
Where? (Does the sample contain substance X?)
How much? (How much of substance X is in the sample?)
What arrangement, structure or form?

3. Chemical analysis includes any aspect of the chemical characterization of a sample material.

4. Techniques in Analytical chemistry

5. What Do Chemical Analysts Do?
Analyst: Applies known measurement techniques to well defined compositional or characterization questions.
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.
Develops new measurement methods on existing principles to solve new analysis problems.

6. 0-2 The analytical Chemist’s job

7. Sampling: Procuring a representative sample
Homogeneous: same throughout
Heterogeneous: differs from region to region
For a segregated heterogeneous material (in which large regions have obviously different compositions), a representative composite sample must be constructed.
In a random heterogeneous material, differences in composition occur randomly and on a fine scale.

8. Project 1: How to measure the caffeine content of a chocolate bar?

9. Step 1: Sample Preparation
--transforming a sample into a state that is suitable for analysis
Weighting
Removing fat with organic solvent

10. 3. Extracting caffeine and theobromine (analytes) with water

11. Step 2: Performing analysis with liquid chromatography

12. Principles of liquid chromatography

13. Step 3: Preparing calibration curves
A graph of detector response as a function of analyte concentration is called a calibration curve or a standard curve.
Standard solution: containing known concentrations of analytes.

15. Step 4: Analyzing the results

17. 0-3 General steps in a chemical 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.

19. Exercise 1:
0-6. The iodide (I−) content of a commercial mineral water was measured by two methods that produced wildy different results.7 Method A found 0.23 milligrams of I− per liter (mg/L) and method B found mg/L. When Mn2+ was added to the water, the I− content found by method A increased each time more Mn2+ was added, but results from method B were unchanged. Which of the Terms to Understand describes what is occurring in these measurements?
Answer:

20. Exercise 2: When performing an analysis a chemist often uses a standard solution. What is a standard solution?
(a) A solution that complies with standards established by the Environmental Protection Agency. (b) A solution that has a concentration of a chemical that is known to a high degree of certainty. (c) A solution that is prepared from a chemical that has been designated as a primary standard.
Exercise 3:
In a random heterogeneous material, (a) differences in composition occur randomly and on a fine scale. (b) large regions have obviously different compositions. (c) samples are collected by taking portions from the desired number of segments chosen at random.