# CE304 Development of calibration curve for a Tracer Hello there, i have attached the lab manual, data and the way how the report needs to be doneI am in gr

CE304 Development of calibration curve for a Tracer Hello there, i have attached the lab manual, data and the way how the report needs to be doneI am in group AThanks Lab 1 – Development of a
Calibration Curve for a Tracer
A. Lab Objectives
1.
Develop a statistically significant calibration curve for both a
spectrophotometer and a colorimeter to measure concentrations of
a tracer dye for use in contaminant transport studies.
2.
Apply the calibration curve to determine the concentration of
tracer dye in unknown sample.
B. Student Learning Objectives
1.
Learn how to operate a spectrophotometer and colorimeter for
reading absorbance of prepared standard solutions of known
concentrations.
2.
Learn how to use Excel for regression analyses to determine a
statistically significant relationship to predict concentration as a
function of absorbance.
C. References
Hach DR900 Colorimeter User’s Manual
Hach DR4000-UV Spectrophotometer User’s Manual
D. Background
Nonreactive (conservative) dyes are often used in environmental studies
to examine how a fluid (air or water) is transported through an
engineered reactor or a natural environmental system such as a lake or
stream. Parameters such as residence times and flow velocities are often
determined from these studies. The dyes should be nontoxic and easy to
detect and measure. Usually a spectrophotometer is required to measure
the absorbance of the dye solution at an optimum wavelength specific to
the dye being used. If a calibration curve is developed for the
spectrophotometer from standard solutions of known dye concentrations,
the absorbance measurements can be translated into dye
9
concentrations (mass/volume). Ideally, a linear equation can be
developed to calculate the concentration as a function of absorbance.
For this lab, both a spectrophotometer and a colorimeter may be used to
develop calibration curves for each instrument. The spectrophotometer
can be used the find optimum wavelength for measuring the dye
absorbance, and then a calibration curve will be developed for the
spectrophotometer at the optimum wavelength. Since colorimeters are
usually limited to one or two specific wavelengths, a separate calibration
curve will be developed using the wavelength closest to the optimum
determined from the spectrophotometer.
E. Equipment
Hach DR4000-UV Spectrophotometer, Hach DR900 Colorimeter, Red
Food Coloring, Volumetric flasks and pipettes
F. Procedure
1.
Standard Solutions
a.
Prepare a 1000 mg/L standard dye solution by adding 1 mL of
dye to 1 L of water. Prepare standard dye solutions of 500
mg/L, 250 mg/L and 100 mg/L by serially diluting the 1000
mg/L using volumetric flasks. For example, transfer 250 mL
of the 1000mg/L solution (using a 250 mL volumetric flask)
into a 500 mL volumetric flask. Add water to bring the new
solution up to 500 mL which will result in a 500 mg/L
standard solution. Invert the new flask to thoroughly mix the
contents.
b.
Repeat the above procedure starting with the 500 mg/L solution
to produce a 250 mg/L standard, and then use the 250 mg/L
standard to produce a 100 mg/L standard.
2.
Dye solutions measurement with the Spectrophometer
a.
Turn on the Hach DR 4000-UV spectrophotometer. After the
spectrophotometer has booted-up, in a single wavelength
mode, setup the wavelength = 500 nm. Place a blank sample
(test tube with tap water) in the cell and press the zero button
to zero the instrument.
b.
Next, sequentially fill a test tube with each of the standard
solutions (triplicates) and measure and record the absorbance
and concentration.
c.
Plot the concentration (X) versus absorbance (Y) to check that a
linear relationship exists. (If the data are not linear, try
running a second set of 10
readings. If they are still non-linear, then a new set of standards should
be prepared).
3.
Dye solutions measurement with the Colorimeter
a.
Place the test tube adapter in the cell holder of the colorimeter
and turn it on. Press the Program button and key in the
wavelength closest to the optimum determined by the
spectrophotometer (for the Hach DR900 Colorimeter, the
wavelengths are 420, 520, 560 or 610 nm). Fill a test tube
with tap water, place it in the cell holder, and place the lid
over the cell holder. Press the zero key to zero the instrument.
b.
Sequentially fill a test tube with each of the standard solutions
(triplicates) and measure and record the absorbance and
concentration for each sample. Plot the concentration (X)
versus absorbance (Y) to check that a linear relationship
exists.
4.
Analyze the tracer concentration of unknown samples Rinse a test
tube with tap water and get the unknown samples from instructor.
Fill a test tube with the unknown samples. Measure and record the
absorbance of the unknown samples (triplicates).
G. Data Analysis and Discussion Questions
1.
Develop an Excel spreadsheet and create a scatter plot of the
absorbance (y-axis) versus concentration (x-axis) data for each
instrument.
2.
Use the Regression function (under Tools, Data Analysis menu of
Excel) to generate the output tables and determine the regression
equation for absorbance as a function of concentration (these tables
should be included in the appendix of the report, but only a
summary table of the relevant information should be provided in
the results section of the main report).
3.
Examine the regression output table to determine whether the
intercept is significant based on the 99% confidence interval for
the intercept (if the 99% CI includes the value of zero, the intercept
is not statistically significant and should be eliminated from the
regression analysis).
4.
If the intercept is not significant, run the regression analysis again
by selecting the value of zero for the intercept. Examine the
regression output table to report the final relationship, the
coefficient of determination (R2), and the 99 % CI for the slope.
The final regression lines can be shown on the plot of the data. For
each regression, the summary tables in the results should show the
estimated values for 11
the slope and intercept, the 99% confidence intervals for the slope and
intercept, and the coefficient of determination (r2).
5. Given the statistically significant results developed for each
instrument, rearrange the equations to solve for the concentration as a
function of the absorbance:
C (mg/L) = a × Abs + b (Eq. 1)
Present the final equations in the report. Apply the equations (one
measure at wavelength = 500 nm and one measure at wavelength = 520
nm) and calculate the concentration of tracer in the unknown samples.
These are the final equations that will be used in later experiments for
determining tracer concentrations for complete mix and plug flow
reactors.
H. Application Problems (Show calculation process and answers in
Appendix)
N/A
Water Resources and Environmental
Engineering Laboratory
Writing Scientific and Engineering Reports
CE 304 SP2019
Technical Writing
Kevin Wang
Outline

Introduction
Structure of a technical report
Writing by Sections
Tips for report writing
How Engineers Spend Their Time: Early Career
25-50
______%
Engineering: Designing, measuring,
calculating, problem-solving
______%
Communicating: Writing reports, letters,
50-75
memos, proposals; giving presentations,
talking to colleagues, supervisors, and
clients
3
https://ibrahimelsawy.files.wordpress.com/2012/02/communication-engineer1.jpg
General Structure of a scientific
Writing
• In scientific writing, IMRaD (Introduction,
Methods, Results, and Discussion,
Conclusion) refers to a common organization
structure
Structure of a scientific /engineering
Report

Title Page
Abstract
Introduction
Methods and Procedures
Results and Discussion
Summary and Conclusions
References
Appendices
Abstract
Brief trajectory (objectives, major findings, conclusion) of the report
Introduction
Background information, importance of the work,
objectives, scope of works
Methods and Procedures
Exp. Procedures
Data Analysis
The steps and equipments Equations, theories, statistic
you used in the lab
tools
Results and Discussion
Visually and textually represents research findings
Interpret the findings: Primary results vs secondary
results; Results vs. theories , Sources of error,
Conclusions
Summary of goals, results and discussion, implication of
the findings
6
Procedures and Methods
How did you do it?
• Experimental Procedures and Methods
– History of work completed
– Make use of illustrations
– Flow chart
Do not provide a step by step set of instructions
that are found in the lab manual!
• Methods of Data Analysis
– Formulas, equations, theory, statistics
Results and Discussion
• Results:
What did you find?
– Present data collected to support objectives
(Tables & Graphs)
– Use sub-headings to keep results of the same type
together, which is easier to review and read
– For the data, decide on a logical order that tells a
clear story and makes it and easy to understand
Results and Discussion
• Discussion:
What does it all mean?
– Discuss results with regard to objectives, explain the
data and significance of the information in the tables
and graphs.
– How do these results relate to the original question or
objectives outlined in the Introduction section?
– Do the data support your hypothesis? Comparison of
results with theory or accepted formulas should be
discussed.
– Sources of error should be addressed with respect to
your findings and the significance of these errors with
respect to the objectives of the lab
Results and Discussion
• Discussion:
What does it all mean?
– Discuss weaknesses and discrepancies. If your
results were unexpected, try to explain why
– Is there another way to interpret your results?
– What further research would be necessary to
– Explain what is new without exaggerating
Conclusions
• Summary of goals
• Summary of Results
– Findings from the data
You should provide a clear scientific
justification for your work in this
section
The Conclusion should concisely
provide the key message(s) the author
wishes to convey
• Implication of the findings
• Summary of recommendations
– Improve the data quality (accuracy or precision)
– Improve the experimental methods
A common error in this section is repeating the abstract, or just listing
experimental results.
Introduction
Why did you do it?
• Background (1st)
What did you do?
– Explain the importance of this lab in Engineering
practice.
• Objectives (2nd)
– State the practical objectives of the lab.
• Scope of works (3rd)
– Provide an overview of the how the objectives
were achieved, that is, what will be done in this
lab.
Move from general to specific: problem in real world / research topics
Abstract
what you did and what the
important findings in your
research were.
• Single page alone! (requirement for the report format
in this class)
• What information should be provided in the Abstract?
– Objectives and Background Statement (1-2 sentences,
What did you investigate? Why?)
– Scope of work(1-2 sentences, What did you do?)
– Highlight Significant Findings (2 to 3 sentences, What did
you find out?)
– State major conclusions and significance. (1-2 sentences,
What do your results mean? So what?)
– One to two paragraphs total (150-300 words)
Abstract
• What to avoid:
– Do not include references to figures, tables,
equations, or sources.
– Do not include information not in report.
– Using jargon, uncommon abbreviations and
references
References and Appendix
• References
– Provide a bibliographic list of references used in the
lab report.
• Appendix (starting from an new page)
– Original data from lab, calculations (or at least one
complete set of well documented sample
calculations),
– Any other related information which supports the lab
report, but does not fit in the main report.
– All information and data needed to develop the
results of the lab or project should be presented
either in the main report or the appendix.
How to start it?
• Suggested writing order:
1.
2.
Perform all required data analysis
Have all the Figures, Tables, or Equations ready
Methods and Procedures
Write down the Exp. Steps ASAP after the lab
3.
Results and Discussion / Appendices
4.
5.
6.
Conclusions
Introduction
Abstract
Major findings should be mentioned
7.
References
But we are not finished yet!
• This is just the “first draft” of your report!
Check ! Check ! Check!
Check List (attach this Table in the last page of your first two reports)
Items
Title page (format)
Structured abstract (Objectives, important findings and conclusion), single page alone
Introduction (Importance, objectives, scope of work)
Experimental Procedures and Data Analysis Methods
Results and discussion (rational thinking, present your data or results in a logical order, sub headings)
Conclusion
Figure legends
Captions for Figure (bottom) and Table (above)
Significant digits (round up to hundredths decimal for most of data) or scientific expression
References are superscript in text.
Text is 12 point, double-spaced.
Text is in Microsoft Word.
Acronym use is limited.
Report has been checked for spelling and grammar.
The report file name should be named in the following way: first name last name_lab#
Answers for Application questions (N/A if there is no application question)
Tips for Report Writing (I)
• Avoid vague generalizations
– “good data”, “very high temperature”, “good R2 values”
Example: In Lab
– Spectrophotometer,
– Colorimeter
• Avoid the use of personal pronouns such as “we” or “I”
– Passive voice
– Student measured the absorbance of unknown samples with colorimeter.
– The absorbance of unknown samples were measured with colorimeter.
• Tense

Past tense to describe what was done
Past tense for results obtained
Past tense to describe findings, with present tense to interpret results
Present tense to refer to figures, tables and graphs
• Avoid long complicated sentences
20
Tips for Report Writing (II)
• Check Spelling and Grammar
– Affect (verb) versus effect (noun).
– Use spell-check and grammar-check!
• Always define Acronyms at the first use
– Open channel flow (OCF)
• Number all Equations, Tables, and Figures
– Eq. 1 or Equation 1; Figure 1 or Fig. 1; Table 1
• All tables and figures must have captions.
– Location of the captions: Figures bottom; Tables  top

All figures must have labeled axes
All quantities must have units
Detailed calculation process could be shown in appendix
Significant digits: 0.009923  9.92×10-3
Be consistent in format
Proofread the report carefully before submit it
21
22
Caption location
No label for axes
No curve was shown
23
ICP 27Al Calibration Curve
ICP 27Al Calibration Curve
7.00E+05
700,000.00
y = 6072.3x + 19574
R² = 0.9908
600,000.00
y = 6.07E+03 x + 1.96E+04
R² = 0.9908
6.00E+05
5.00E+05
500,000.00
4.00E+05
Counts
400,000.00
3.00E+05
300,000.00
2.00E+05
200,000.00
1.00E+05
100,000.00
0.00E+00
0.00
0
20
40
60
80
Standard Concentraiton (ppb)
100
120
0
20
40
60
80
100
120
Standard Concentraiton (ppb)
24
25
Results and Discussion (IV)
• The concentrations of Al were both very low in both
samples. The concentration of Ca in the tap water was
twice as high as that of the groundwater sample, which
can be expected because it is normal for tap water to have
minute concentrations of necessary minerals. However,
the groundwater contained far higher concentrations of
manganese. Comparable and low Ni and Pb concentrations
were observed.
vague generalizations
26
Primary data?
Secondary data?
Conclusions (I)
28
Conclusions (II)
29
References
1.
2.
CE 304 Water Resources and
Environmental Engineering
Laboratory Manual
Wikipedia.org
1.
2.
3.
4.
Tchobanoglous, G., Burton, F.L., and
Stensel, H.D. (2003) Wastewater
Engineering, Treatment and Resuse/
Metcalf and Eddy, 4th Edition. McGrawHill. Chapter 3.
Tchobanoglous, G., Burton, F.L., and
Stensel, H.D. (2003) Wastewater
Engineering, Treatment and Reuse/
Metcalf and Eddy, 4th Edition. McGrawHill. Pp 475-500.
Introduction to Gas Chromatograph.
http://teaching.shu.ac.uk/hwb/chemistry/
tutorials/chrom/gaschrm.htm
Davis, John. (2006) Water Resources and
Environmental Enginering Labratory
Manual.” Widener University Dep. of Civil
Engineering. Pp 16-20.
30
“Writing is an art. But when it is writing to
inform it comes close to being a science as well.”
–Robert Gunning, The Technique of Clear Writing
I believe in miracles in every area
of life except writing. Experience
has shown me that there are
no miracles in writing.
The only thing that produces good
writing is hard work.
(Isaac Bashevis Singer, Nobel Prize in Literature in 1978)
https://blotterpaper.files.wordpress.com/2013/02/working-hard.jpg
31
Spectrophotometer
Wavelength
Total # of test
Group A
Group B
Colorimeter
Wavelength
Total # of test
500 nm
24
Conc. (mg/L)
100
100
100
250
250
250
500
500
500
1000
1000
1000
100
100
100
250
250
250
500
500
500
1000
1000
1000
Abs
0.211
0.217
0.218
0.562
0.569
0.576
1.172
1.177
1.175
2.134
2.142
2.144
0.228
0.226
0.223
0.567
0.568
0.575
1.161
1.183
1.183
2.148
2.180
2.181
Group A
Group B
Unknown Sample
Total # of test
520 nm
24
Conc. (mg/L)
100
100
100
250
250
250
500
500
500
1000
1000
1000
100
100
100
250
250
250
500
500
500
1000
1000
1000
Abs
0.182
0.182
0.183
0.516
0.515
0.518
1.049
1.058
1.055
1.929
1.962
1.972
0.186
0.185
0.185
0.518
0.518
0.519
1.057
1.059
1.057
1.975
1.979
1.974
6
Group A, B
1
2
3
4
5
6
Average =
Abs at
500 nm
520 nm
0.873
0.817
0.876
0.821
0.874
0.820
0.918
0.826
0.919
0.825
0.919
0.827
0.897
0.823
1. Run the regresion analysis according to
from each equipment.
2. Report the required values such as slope
(refer the lecture slide examples)
3. The significant digits: use the scientific e
hundredth digits for most of the factors in
value can be down to thousandth digits.
4. See the plotting example (in the next sp
value can be down to thousandth digits.
4. See the plotting example (in the next sp
to plot the calibration curve equation line
1. Convert the Abs. from each test with
the calibration curve equation.
2. Take the average of the concentration
values and calculate the standard
deviation. Report the averagred
concentration with standard deviation.
analysis according to the results (24 tests)
ed values such as slope, intercepts… etcs.
de examples)
its: use the scientific expression to
most of the factors in this lab report. R^2
o thousandth digits.
xample (in the next spreadsheet) for how
o thousandth digits.
xample (in the next spreadsheet) for how
on curve equation line with the experimental
Spectrophotometer
Wavelength
Total # of test
Group C
Colorimeter
Wavelength
Total # of test
500 nm
12
Conc. (mg/L)
100
100
100
250
250
250
500
500
500
1000
1000
1000
Abs
0.224
0.227
0.224
0.567
0.575
0.572
1.178
1.176
1.176
2.183
2.181
2.183
Group C
Unknown Sample
Total # of test
520 nm
12
Conc. (mg/L)
100
100
100
250
250
250
500
500
500
1000
1000
1000
Abs
0.175
0.171
0.170
0.500
0.501
0.499
1.036
1.036
1.034
1.943
1.950
1.949
6
Group C
1
2
3
Average =
Abs at
500 nm
520 nm
0.920
0.806
0.918
0.805
0.919
0.806
0.919
0.806
1. Run the regresion analysis according to the
from each equipment.
2. Report the required values such as slope, in
(refer the lecture slide examples)
3. The significant digits: use the scientific expr
hundredth digits for most of the factors in this
value can be down to thousandth digits.
4. See the plotting example (in the next sprea
to plot the calibration curve equation line with
1. Convert the Abs. from each test with
alysis according …