Lab Report Format
CHEM 155 Instrumental Analysis Prof. Terrill
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Reports will have 8 sections with the following weights:
1 – Cover page
02
2 – Abstract
13
3 – Introduction
15
4 – Experimental
15
5 – Analysis, Results and Discussion
15
6 – References
10
7 – Figures and Tables
15
8 – Appendix
15
Total
100 points
1. Cover page:
1.1. Title
1.2. Your name
1.3. Your partner’s name
1.4. Course
1.5. Professor Terrill
1.6. Date Submitted
2. Abstract: In a few short sentences convey
(a) the general idea of the experiment, (b)
what was done and how including
important details such as the wavelengths
used and (c) the final results, including
errors (σ) and detection limits where
appropriate.
The boxes below contain some key
points that I look at when scoring
the reports!
Idea, experiment, critical details, Zn
results, errors, Fe results, errors,
mg/pill units?, expected values,
validations, detection limits,
wavelength, stationary phase,
mobile phase
3. Introduction: This is a summary of the analysis.
3.1. It should include a short description of the analytes – what they are why
they are there and why it is important to know how much of these
analytes are present in your sample.
3.2. A discussion of the instrumental method that you are using should also be
included. Discuss how the instrument works and focus on the principles
of the detection or separation e.g. the absorption of light by gas phase
atomic analytes or the partitioning of analytes from a solution (mobile
phase) to a stationary phase.
3.3. Mention the various experimental parameters that influence the
performance of the instrument and why – e.g. flame stoichiometry or
mobile phase composition, wavelength etc.
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Lab Report Format
CHEM 155 Instrumental Analysis Prof. Terrill
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4. Experimental
4.1. Instruments and Materials: (A) List the name and manufacturer of the
instruments you used, e.g. “Unicam 929 AA spectrometer…” (B) Next,
list the reagents that you used, including the water. It is acceptable to
indicate that these were obtained from the SJSU Chemistry Service if
more detailed information is not available. Indicate the manufacturer and
the purity where available (e.g. with the concentrated acids since they
contain trace metal impurities). Column type, flame type, stationary
phase etc.
4.2. Procedure: In this section,
Sample, standard, validation, & buffer
describe what you did in such a
preparations.
way that another chemist could
look at it and reproduce your
UV-Vis experiment (HPLC)
work. It is not a set of step-bystep instructions – but rather a
Implementation of HPLC – flow rate,
concise description of what you
pressure, injection volume, injection
actually did. For example: “The
time, sample vials, injection order.
calibration primary standard
(1002.3 PPM) was prepared by
dissolving 1.0023g of Co metal in yy mL of HNO3 (conc.), and diluting to
1.000 L with distilled water. Validation standards were similarly prepared
to yield two, 500mL solutions of qq and zz PPM” “The working standards
were prepared by serial dilution of the standards in the following way…
The concentrations are listed in Table 1.” The standard concentrations
and signals will be tabulated in the results section – see the below for
details. Important experimental parameters used should be mentioned
here. For example “For the FAAS analysis, an Air-acetylene flame
source, hollow cathode lamp radiation source and a wavelength of xxx.x
nm were employed ”. A common mistake is to claim that your standards
are 10 ppm when they are actually 10.1 because the primary calibration
standard was based on 101 mg instead of 100. I encourage you to make
tables in this section – just state that a certain general procedure was
used and then give the details in the table. This is much easier to real
than a litany of repetitious sentences describing essentially the same
thing but Tottering only in one or two numbers.
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Lab Report Format
CHEM 155 Instrumental Analysis Prof. Terrill
5. Analysis, Results and
Discussion: Describe the results of
your measurements in words and
figures.
5.1. Refer to the various numbered
figures (spectra,
chromatograms or graphs) and
tables in turn and discuss the
results. Where possible, you
explain (a) why the results are
what they are and (b) what they
mean and (c) how you used
them. Don’t forget to mention
relevant measurements such as
the UV-Vis absorbance spectra
and retention times for the
HPLC experiment.
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UV-vis results, Calibration, linear
regression and error calculations,
problems in chromatogram or with
spectrometer.
Sample-sample variation versus
standard deviation estimate
based on calibration curve.
Agreement with expectation – is
difference between expected
value and measured value larger
than the standard deviation. This
question applies to both the
validations and the samples.
What does this mean?
Comments on chromatogram –
elution order, resolution etc.
5.2. Make a table of absorbance
and concentration values including the appropriate uncertainties for all of
your samples, calibration and validation standards. I include an example
for the FAAS experiment below:
Table 1. Absorbance Data
Sample
1
2
3
4
Validation 1
Validation 2
Spinach
•
•
C [PPM]
1.23
4.45
10.2
20.2
12.2
9.23
----------
Absorbance
Note in this section if any of the calibration data were thrown out!
Note whether the validation data were in agreement with the calibration
or not. According to the validation standards, how accurate are the
results?
5.3. Make a calibration graph from your analyte absorbance values as
illustrated below. It can be on a separate page. All the points are shown,
including the regression line, validations, and the sample absorbance is
indicated with a horizontal line intersecting the calibration line. The
uncertainty of the sample absorbance (if known) is indicated by two
parallel lines drawn at the sample absorbance plus and minus the
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Lab Report Format
CHEM 155 Instrumental Analysis Prof. Terrill
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standard deviation in the sample absorbance. Your experimental
uncertainty may be too small to do this graphically, but it illustrates nicely
the way that the uncertainty in the sample absorbance propagates into an
uncertainty in the sample concentration. You may be able to address the
question of whether this instrumental method is suitable in terms of
detection limit for the given analysis
5.4. Finally, discuss the least-squares (linear regression) analysis. Note that
this implies that you are fitting the data to a model, e.g.
A = m*C[PPM] + Sb. Report the best-fit sensitivity, m, and blank signal,
Sb and their respective uncertainties. Put the actual regression and
propagation of error calculations in the appendix.
5.5. Do not forget to list the final results of the analysis here. This means the
amount of the analyte that is in a meaningful amount (e.g. a serving) of
the original sample, e.g. 4 grams of spinach or 12 ounces of diet coke.
Compare this value to what is expected for this product.
5.6. Make it clear that you understand the results. Discuss the relative value
of the validation versus random errors. Do sample-to-sample variations
swamp the calculated standard deviations and if so, what does this
mean?
6. References: List the references here that correspond to the numbered
citations in the text. Please cite at least one source relating to the analytical
method used other than the textbook for the class and one relating to either a.
the general importance of analyzing for the particular analyte(s), or b. the
particular problem of measuring, e.g. Fe using FAAS. All references included
should be cited in the paper. Web URL’s do not count.
7. Tables and Figures: Put the titled and numbered tables and figures together,
in order immediately following the references. Mainly, this is a place to
summarize the results. Please only put here the figures and tables that you
produce, not the ones that the instrument makes. Finally, every figure that
you put here should be referred to in the text. All figures must be clearly
labeled. Avoid dark backgrounds and unnecessary information. Neat hand
work on figures is perfectly acceptable.
8. Appendix: Put your calculations here. Neat handwork is fine – but I expect
to see samples of all the important calculations that you performed. If you
used a computer program (e.g. Microsoft Excel) please print out a report
from the program illustrating the results. I do not expect anyone to do the
linear regression by hand! Your legible notebook carbons may suffice for
the experimental parts here.
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Lab Report Format
CHEM 155 Instrumental Analysis Prof. Terrill
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9. An example of a calibration curve showing the sample absorbance (and
confidence intervals or standard deviations) along with validation points is
below. Your graph does not need to look identical to this one.
Primary Calibration Standards
First Validation Standard
Second Validation Standard
Digested Spinach Sample
0.5
Absorbance
0.4
0.3
0.2
0.1
0.0
0
2
4
6
8
10
12
14
16
18
20
Mg Concentration [PPM]
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