1. Exploring Chemical Analysis Fourth Edition
The Analytical Process
P.1

2. Average of the four examinations ≧ 55
Syllabus
Class ch
Class ch
Classes 3 ~ spectroscopy in ch and supplementary material
Class ch 21 + exam 1
Classes 7 ~ chromatography in ch 21-23
Class exam 2
Classes 10 ~ titration in ch (skip ch 12)
Class exam 3
Classes 15 ~ electric chemistry in ch 14-17
Class exam 4
Requirement
Average of the four examinations ≧ 55

3. Reference 1
Textbook
Reference 2

4. Analytical chemistry is applied throughout industry, medicine, and all the sciences.
Skoog

5. Example: analyze theobromine and caffeine in chocolate bars
chocolate packs an extra punch from the stimulant caffeine and its biochemical precursor, theobromine.
Theobromine
Diuretic, smooth muscle relaxant, cardiac stimulant, and vasodilator
Caffeine
Central nervous system
stimulant and diuretic

6. Sampling Sample Preparation
The first step in any chemical analysis is procuring a representative, small sample to measure－a process called sampling 取樣.
Sample Preparation
Homogeneous and heterogeneous samples need different preparation procedures.
Ceramic mortar and pestle used to grind solids into fine powders.

7. Figure 0-2
Extracting fat from chocolate to leave defatted solid residue for analysis.
Substances being measured - caffeine and theobromine in this case - are called analytes.

8. Centrifugation and filtration are used to separate undesired solid residue from the aqueous solution of analytes. 離心
The cloudy, tan, supernatant liquid (liquid above the packed solid) was then filtered in a further attempt to remove tiny particles of solid from the liquid.
Sample preparation transforms sample into a state that is suitable for analysis.

9. The Chemical Analysis flows out first Chromatogram flows out latter
Chromatography (層析法) column separates the analytes and measures their quantity.
The column is packed with tiny particles of silica (SiO2) on which are attached long hydrocarbon molecules.
flows out first
Chromatogram
Chromatogram of 20.0 mL of dark chocolate extract. A 4.6-mm-diameter× 150-mm-long column, acked with 5-mm particles of Hypersil DS, was eluted (washed) with water:methanol: acetic acid (79: 20: 1 by volume) at a rate of 1.0 mL per minute.
flows out latter

10. qualitative analysis: Identifying what is in an unknown
quantitative analysis:
Identifying how much is present
In the chromatogram, the area under each peak is proportional to the quantity of that component passing through the detector.

11. Calibration Curves
A graph showing detector response as a function of analyte concentration is called a calibration curve or a standard curve.
To construct a calibration curve, standard solutions containing known concentrations of pure theobromine or caffeine were prepared and injected into the column, and the resulting peak heights were measured.

12. Interpreting the Results
A can of soft drink or a cup of tea contains about one-quarter to one-half of the caffeine in a small cup of coffee.

13. Quality Assurance (品質保證)
Professional analysts follow a set of practices, called quality assurance, intended to give themselves and their customers confidence in the quality of their results.

14. General Steps in a Chemical Analysis
Formulating the question
Translate general questions into specific questions to be answered through chemical measurements.
Selecting analytical procedures
Search the chemical literature to find appropriate or, if necessary, devise new procedures to make the required measurements.
Sampling
Select representative material to analyze.

15. Reporting and interpretation
Sample preparation
Sample preparation is the process of converting a representative sample into a form suitable for chemical analysis, which usually means dissolving the sample.
Analysis
Measure the concentration of analyte in several identical aliquots (portions).
Reporting and interpretation
Deliver a clearly written, complete report of your results, high-lighting any special limitations that you attach to them.
Drawing conclusions
Once a report is written, the analyst might not further participate in what is done with the information.

16. Skoog

17. Quantitative Analytical Methods
Gravimetric methods chapter 7
determine the mass of the analyte
Volumetric method chapters 6, 8, 9, 10, 11, 13
measures the volume of a solution containining the analytes
Electroanalytical methods chapters 14, 15, 16, 17
determine the electrical properties as potential, current, resistance, and quantity of electrical charge of analytes
Spectroscopic methods chapters 18, 19, 20
measurement of the interaction between electromagnetic radiation and analyte atoms or molecules or on the production of such radiation by analytes.
Chromatography chapters 21, 22, 23
separates the analytes from a mixture and measure the quantity of analytes