Syllabus for CHEM 3281
Fall Semester, 2003
Faculty:
Dr. Richard F. Browner
Boggs Chemistry & Biochemistry, Rm. B-20 (404) 894-4020
rick.browner@chemistry.gatech.edu
Lab Coordinator: Dr. Robert Braga
TAs:
Lecture:
MWF 12-110 p.m. (Boggs 2-28)
Laboratory:
W 2:00-5:00 p.m. ( Boggs 1-72)
Required Text:
"Chemical Analysis: Modern Instrumentation, Methods and
Techniques" F. Rouessac and A. Rouessac, Wiley & Sons,
Chichester, 2001
Recommended:
“Analytical Instrumentation: Performance, Characteristics and
Quality” G. Currell, Wiley & Sons, Chichester, 2000
Objectives:
Survey of analytical instrumentation and techniques specifically for
engineering students
Goal: to provide engineering students with a fundamental understanding of
chemical analysis and appropriate figures of merit (sensitivity, selectivity, limitof-detection, etc.) enabling them to communicate effectively with analytical
chemists and properly interpret analytical results presented to them.
Lecture topics/readings provide the student with the theoretical basis for each
week’s experiments.
The laboratory will provide the student the opportunity to become acquainted
with a particular laboratory instrument and use it to perform a specific analysis.
Objectives (cont’d):
The course grade will equally weight the student’s performance in lab and
lecture.*
Final grades will be given based on the following scale:
A (100 – 80%)
B (79 – 70%)
C (69-60%)
D (59-50%)
F (below 50%)
There will be two (2) one-hour Exams and a Final Comprehensive Exam,
covering all the course lecture material (see Calendar). Each one-hour exam
will be worth 15%, and the final exam will be worth 20%.
As the final exam is comprehensive, your grade on the final exam, if it is
higher than your average course grade, including one-hour exams and labs.,
will determine your overall final grade.
* To pass the course as a whole, a passing grade (i.e >50%) is required in both lab
and lecture.
General Information and Policies:
Lectures will be devoted to both theoretical and practical aspects of the analytical
procedures encountered in the laboratory. Lecture topics, exam dates, and suggested
readings are available on the WebCT site for this course.
Attendance at laboratory is required of all students. Students must be on time for each lab
meeting since the laboratories are tightly scheduled and there is very little free time
available. The lab will not be open at hours other than those scheduled. Students may not
under any circumstances work in the laboratory without supervision.
Wearing safety eyewear in the laboratory is absolutely mandatory! You will be asked to
leave the lab and obtain safety eyewear if you are found without it. There will be no
exceptions to this rule.
Each student is required to keep and maintain the equipment in working order. Instructions
for each laboratory experiment are available on-line under WebCT.
Each student is required to maintain a laboratory notebook. The notebook must have a
sewn-in binding with the ability to make a carbon copy of each page. A carbon copy of the
notes and data you obtained must be turned into the TA at the completion of each lab
experiment.
Initial Tasks:
Prior to beginning laboratory work each student must:
Sign and date two copies of the Safety Notes page, retaining one copy for your
records.
 Maintain a $50 balance on your Buzz Card for replacement of lost or broken lab
equipment.
 Purchase a laboratory notebook (with carbon copy pages) and safety goggles.
Lab begins this week with Experiment #1.
This is your eye!
This is your eye after attack by caustic.
This is your eye after attack by acid.
This is your eye after attack by foreign objects.
Is it worth the risk?
What you can expect from
Experiment #1?
?
Pellet #
1
2
3
4
5
6
7
8
9
10
11
Black
5.4730
5.6881
5.5188
5.6104
5.2834
6.1358
6.0242
5.2807
4.4559
5.5548
5.6031
Max
Mean
Min
S.D.
6.1358
5.5117
4.4559
0.4387
Repeated
Measurement
5.6881
5.6880
5.6883
5.6884
5.6882
Mean = 5.6882
S.D. = 0.0002
What conclusions can be drawn?
Rejecting Outliers - The Q-test
d
Y1
range
Qcalc = d/range
Discard outlier if and only if
Qcalc > Qcrit. Q-test may be used
to reject only one data point per
set.
Critical Values of Q
Measurement Precision vs.
Sampling Variance
Pellet
#
1
2
3
4
5
6
7
8
9
10
11
White
Max
Mean
Min
S.D.
5.9340
5.6002
5.3670
0.2186
5.9340
5.6096
5.8875
5.4040
5.4187
5.7357
5.4065
5.4027
5.3670
5.5853
5.8508
Repeated
Measurement
5.6096
5.6092
5.6097
5.6099
5.6094
Mean = 5.6096
S.D. = 0.0003
What conclusions can be drawn?
Are the two sets of data significantly different?
Y1
Y1
Hypothesis testing
The null hypothesis is disproved when tcalc > tcrit. There exists a significant difference
between the two data sets. When tcalc < tcrit the null hypothesis cannot be rejected and
no significant difference between the two sets exists.
Student’s t test
Critical Values of t
Testing the Null Hypothesis
The null hypothesis is
disproved only when
tcalc > tcrit
and the alternate hypothesis
is accepted.
accept
tolerate
reject
Note: The overall variance of an analysis is a function of
the precision of the measurement and the variability of
the sample.
Figures of Merit for Analytical Methods
 Precision - absolute or relative standard deviation,
variance, coefficient of variation
 Accuracy (or bias) – absolute or relative error
 Sensitivity – calibration or analytical sensitivity
 Detection limit – limit of detection, limit of quantitation
 Concentration range – linear dynamic range
 Selectivity – coefficient of selectivity
Precision vs. Accuracy
Low accuracy
Low precision
High precision
High accuracy
Accuracy
Error – difference between your answer and the “true” one.
absolute error = observed value – true value
relative error = 100 * absolute error/true value
Types of Error:
Systematic – all measurements deviate from the true value by
the same magnitude and direction indicating a problem with
the method
Random – random variations in measurement that can be
treated statistically
Blunders - human error in performing method that prevent
acquisition of reliable measurement
What do you do when you don’t know the true value?
Precision establishes
repeatability of measurement,
not accuracy
Sensitivity
sensitivity = slope
R = mX + b + residual
Detection
Concentration Range
Linear dynamic range = # orders of magnitude in
concentration that response is linear
Selectivity
For a sample containing an analyte A as well as potential interfering species
B and C, the instrument signal, S, will be:
S = mACA + mBCB + mCCC + Sblank
The selectivity coefficient for A w/r B is:
kB,A = mB/mA
Thus, B interferes when mB is > 0
When selectivity coefficients are known for interferences in a sample matrix,
the concentration of the unknown can still be determined using the following
equation:
S = mA (CA + kB,ACB + kC,ACC) + Sblank
Note: if the presence of C suppresses the value of
mA, the sign of kC,A will be negative.