地質分析化學 Geo-analytical Chemistry

沈川洲 Chuan-Chou (River) SHEN; river@ntu.edu.tw

Course Description:This course is intended for graduate students in the Dep

t. of Geosciences, without an extensive background in chemistry. It emphasizes both theoretical and practical aspects of analytical techniques for geochemical research. Modern instrumental techniques and experimental methods will be included. Paper reading, discussion and presentation will also play essential roles in class. After taking this class, students will be able to design an overall experimental procedure, including estimating sample size, sampling, choosing chemicals and labwares and selecting measurement methods for their projects. They will also learn how to independently accomplish chemistry in a geochemical lab.

Literature:Quantitative Chemical Analysis by Daniel C. Harris

Fundamentals of Analytical Chemistry by Skoog and West

Statistics for Analytical Chemistry by Miller and Miller

Data Reduction and Error Analysis for the Physical Sciences by Bevington and Robinson

Text materials: Selected chapters, class handouts, papers.

Credits: 2

Class hours: 7:00-9:00 pm, Thursday

Grading: Homework, 10%; Midterm exam, 30%;Report and presentation, 20%; Final, 40%.

Syllabus:Sept Introduction, Uncertainty, Probability, distributions.

Oct Error analysis.

Significance tests.

Regression correlation.

Methods for quantitative analysis.

Nov Geochem lab: labwares, clean room, QA/QC.

Geochem lab: acids, standards, spikes, safety rule.

Samples and sampling.

Nov27 Midterm exam.Dec Dissolution and separation techniques.

Ion exchange chromatography.

Analytical methods for geo-environmental samples.

Dec 18 2003 AGU Fall Meeting.Jan Paper discussion. Geo-analytical techs.

Analytical methods for geo-environmental samples.

Jan 15 Final; oral exam.

1. Introduction

1.1. Types of geochemical surveysa. Rock surveys

b. Sediment and soil surveys

c. Stream, lake and ocean water surveys

d. Vegetation (biogeochemical) surveys

e. Gas surveys

a. Increased availability of toxic Al3+ to a pine tree in Germany near a coal-burning power plant built in 1929. The increase is probably an effect of man-made acidity in rainfall, which mobilizes Al3+ from minerals.

b. The growth of atmospheric CO2. CO2 comes from our burning of fossil fuel and destruction of forests.

c. The growth in world population.

How long will our planet remain habitable if we do not control our population and our impact on the environment?

2. Uncertainties in measurements

2.1. Analytical problems: qualitative1. Does this distilled water sample contain any boron?

2. Could these two igneous rock samples have come from the

same site?

3. How much lead is there in this sample of tap-water?

2.2. Answers: quantitative

I can/cannot detect boron in this water sample.

A quantitative method capable of detecting boron at levels

of 1 g/ml

This sample contains < 1 g/ml boron

(detection limit).

This sample contains > 1 g/ml boron (e.g. 1.4 g/ml)

(1.4 ± 1.2 g/ml; 1.4 ± 0.2 g/ml; 1.40 ± 0.02 g/ml).

2.3. Types of error

2.3.1. Gross error (gross mistake)

reversing a sign, using a wrong scale, arithmetic

mistakes…

2.3.2. Determinate error (systematic error)

a. Instrument errors

b. Method errors

c. Personal errors

Constant vs. Proportional

The accuracy of an experiment is dependent

on how well we can control or compensate

for systematic errors. Systematic errors affect

accuracy, i.e. proximity to the true value.

Errors make results different from the true

values with reproducible discrepancies.

How to reduce systematic errors?

2.3.3. Indeterminate error (random error)Indeterminate error arises from uncertainties in a measurement that are unknown and not controlled by the scientist (operator). The precision of an experiment is dependent on how well we can overcome random errors. Random errors affect precision, or reproducibility, of an experiment.

To reduce random errors: a. Repeating the experiment b. Improving the experimental method c. Refining the techniquesRepeatability: within-run precisionReproducibility: between-run precision

Repeatability: within-run precision

Reproducibility: between-run precision