Boston College Chemistry Experiment Data Analysis Paper The first attachement is the experimental dataThe second attachement is the content of the experime

Boston College Chemistry Experiment Data Analysis Paper The first attachement is the experimental dataThe second attachement is the content of the experiment The third attachement are the guidelines and requirements of this paper, you should follow it. Internal Standards
Author:
Group:
Contributions:
Dave X: Calculations, Data and Results, Discussion Conclusion
Muhammad Y: Calculations
Han Z: Calculations
Performed: August 31, 2014
Submitted: Sep 04, 2014
Results:
Table 1. Resulting concentrations from the two instruments, the confidence interval
for the results, and literature values.
Table 2. Results of the t-tests for unknowns for instrument 1
Table 3. Results of the t-tests for the literature t-tests
Table 4. Results of the paired t-test
Analysis/Discussion:
[Discuss the results that we get. Each table and figure needs to be discussed/tied together
and referenced by Table/Figure #.
Context for the method.
What does it mean for unknowns to be the same or different? What does it mean for the
paired t-test so show they are the same?Answer the post-lab questions. ]
[If an equation was used to find a reported value make sure to incorporate it appropriately.]
Example equation:
= + (1),
Where y is the dependent variable, m is the slope, b is the y intercept, and x is the
independent variable.
Example Table:
Table 1 Results of the fitting reported with two standard deviations.
Slope (units)
Intercept (units)
Value
A
C
+/- 2 standard deviations
B
D
[Discuss the actual meaning of the results and how they compare to your hypotheses. Do
your results confirm the answers to your Pre-lab questions? Why or why not ? Include any
error analysis here. Address any problems in the experiment, how they could have affected
the outcome, and how they could be fixed. This section is the most important because it is
where you will show your level of comprehension of the science going on in the
experiment.]
Conclusion:
[In a way, the conclusion is a summary. Include the major findings of the
experiment and explain why the results are significant. You may also want to propose an
interesting future experiment that builds on the one you have just reported. This is often
done in journal articles to answer a question that was raised by the results of the original
experiment. Any other observation that was made should be summarized here.]
This document has presented an acceptable way to present your results for a laboratory
experiment, provided example of figures and tables, and provided useful questions to
answer for different sections.
References:
If you used any sources, including the ones provided for the class, cite them here
and reference them in the text. JACS formatting.
General Tips:
Write the report in the 3rd person passive voice i.e. “This was done” not “We did this” or
in the active voice. Be consistent.
– A lab report has no strict minimum or maximum length. It concisely states what needs
to be said about the experiment and then it ends. Guideline: If you are over 4 pages it is
probably too long.
– It is very important to only draw conclusions from the results you actually obtained in the
lab and not the ones you “should” have obtained. Do not assume that there are correct
results and incorrect results. You are encouraged to compare your results to those of other
groups or other similar experiments and reflect on what may have caused the differences
but in the real world there is no “right answer” to check yours with.
– The purpose of a lab report or paper is to communicate your finding to the rest of the
community. As such, you will be mentioning your key results multiple times in the report.
A good format for the overall report follows this basic structure: Tell them what you are
going to tell them (abstract), tell them (The middle stuff), and then tell them what you told
them (Conclusion).
Alternate Figure examples:
Fig. 2: Fluorescence spectra of pyrene using 362nm excitation.
Compiled Experiments
1
Internal Standard: Standards (ISS)
Learning objects
By the end of this experiment students will:
1. Have calculated response factors for four monoterpenes from a standard solution.
2. Used the response factors to determine the concentration of monoterpenes in 3 different
standard solutions.
3. Have evaluated the accuracy of their results.
4. Have determined the precision of their results.
5. Compared their results with their partner group.
Pre-Lab Questions
1. In your own words, what is an internal standard?
⚫ An internal standard is when the standard analyte and the unknown measured in the
same mixture.
1. Have you ever used an internal standard before?
⚫ SACV
2. Why do you have to run standard solutions when using an internal standard?
⚫ The standard solutions provide a reference point to the unknown analyte
3. Why do you think it is called response factor?
⚫ Response factor shows how the response depends on the instrument and analyte’s
interactions.
4. What does a response factor of 1.5 tell you about the relative sensitivity of the instrument
to the internal standard and analyte?
⚫ A 1.5 response factor tells us the relative sensitivity of the instrument in comparison to
the internal standard and analyte is standard is 1.5 times that of the analyte’s peak.
5. You have a response factor of 1.5 and concentration of internal standard of 2mg/mL and
areas of 300 and 800 for the standard and the analyte respectively. What is the analytes
concentration?
⚫ Ax = 800, As = 300, F = 1.5, S =2 mg/mL
1.5*(300/2mg/mL)
X = 800*2 mg/mL/ (300*1.5) = 3.5 mg/mL
6. Do you think response factor for each analyte will be the same or different?
⚫ I think the response factor for each analyte will change for each analyte
7. In the procedure look for key words like record, calibrate, make, or prepare in order to
identify what information you will be using later. Add in relevant empty data tables to the
procedure, label columns and rows appropriately so you can be prepared to record this
information.
8. Does anything need to be added to or removed from the Materials and Safety for Part 1?
Update if necessary.
9. What is the goal for today? What is the basic idea for the technique to be used today?
⚫ To identify the composition of the unknown compounds using internal standards and
the instruments GC-MS and the GC.
Researchers signature:
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Instructor Signature:
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Compiled Experiments
2
Researchers signature:
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Instructor Signature:
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Compiled Experiments
3
Materials:
Chemicals
Volume/Mass
D-limonene
[2 mg/mL]
gamma terpinene
[2 mg/mL]
beta pinene
[2 mg/mL]
alpha pinene
[2 mg/mL]
ethylisovalerate
100mg per unknown =
200 mg total
methylene chloride
[2 mg/mL] 70 mL per
unknown = 140 mL
Equipment
Number/Size
GC-MS
1
GC
1
vacuum extraction apparatus
1
small beakers or vials
2
25mL volumetric flask
1
two GC vials
Per standard
125mL Erlenmeyer flask
1
graduated cylinder
1
filter cake
1
Mass balance
1
GC vials
16
Compound/structure
Hazards
Classification
Handling
(Summary of
section 2 of SDS,
less than 15 words)
D-limonene
Disposal
(Summary of
section 7 of SDS
less than 15
words)
Flammable liquid Lab coat, goggles, EH&S
and vapour. Causes gloves
skin
irritation.
Causes serious eye
irritation.
May
cause respiratory
irritation
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Instructor Signature:
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Compiled Experiments
4
gamma terpinene
Flammable liquid Lab coat, goggles, EH&S
and vapour. Causes gloves
skin
irritation.
Causes serious eye
irritation.
May
cause respiratory
irritation
beta pinene
Flammable liquid Lab coat, goggles, EH&S
and vapour. Causes gloves
skin
irritation.
Causes serious eye
irritation.
May
cause respiratory
irritation
alpha pinene
Flammable liquid Lab coat, goggles, EH&S
and vapour. Causes gloves
skin
irritation.
Causes serious eye
irritation.
May
cause respiratory
irritation
ethylisovalerate
Flammable liquid Lab coat, goggles, EH&S
and vapor. Causes gloves
skin irritation
methylene chloride
Toxic if swallowed. Lab coat, goggles, EH&S
Causes severe skin gloves, venilation
burns and eye
damage. Suspected
of causing cancer.
Introduction
A known amount of a known compound that is not your analyte is considered an internal standard.
This internal standard gives you a reference point to compare the amounts of analyte present.
This method is valuable to use if instrument has slightly varying responses each run or sample
quantity varies from run to run or sample is lost during preparation. The instrument though will
have a consistent relative response to both the analyte (x) and the internal standard (S). For instance,
using a chromatogram of sample eluting will have an area the analyte’s peak (Ax) and the internal
standards peak (As). These are then related to each other through equation 1.

[ ]

= [ ]
(1)
Where F is the response factor. The response factor takes into account differences in how the
sample has transported through the system and how effectively the instrument responds to your
compound of interest.
Researchers signature:
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Instructor Signature:
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Compiled Experiments
5
In an analysis, start with a solution where you know the concentration of your internal standard
and your analyte. Using this information, you can determine the response factor. This response
factor for an analyte will not change during your analysis. Make sure that the internal standard is
added at or near the beginning of sample preparation in case any sample is lost in the process the
internal standard undergoes similar losses. This keeps the relationship between internal standard
and analyte consistent throughout the entire process.
The instrument we are using is a gas chromatograph (GC) that may be coupled to a mass
spectrometer (GC-MS). This instrument first separates components based mainly on their boiling
points (GC) and then generates a mass to charge spectrum of the components as they enter the
mass spectrometer. This enables you to identify a component not just by their retention time, but
also their fragmentation pattern. The sum of all mass to charge components at a given point in time
is related to the concentration of the material coming off of the GC.
You will be studying solutions of monoterpenes with an internal standard of ethylisovalerate.
Procedure
You will be provided with two unknowns for determination.
Sample preparation:
Standards preparation
1. Prepare a single solution that contains 2 mg/mL of each of the monoterpenes (D-limonene,
gamma terpinene, beta pinene, and alpha pinene) and ethylisovalerate in a 25mL volumetric
flask with methylene chloride as your solvent. This is called your standards solution.
Transfer a portion into two GC vials.
2. In a 25 mL volumetric flask, prepare a solution that contains only the internal standard in
methylene chloride (conc. 2 mg/mL).
3. Repeat step 2 for each monoterpene. They do not contain internal standard.
4. Start running these samples on the instruments while you prepare the unknowns.
ethylisovaler
ate
alpha pinene
Beta pinene
D-limonene
gamma
terpinene
Purity
error
in
balance (mg)
Unknowns preparation
1.
2.
3.
4.
5.
Put together a vacuum extraction apparatus as shown by an instructor.
Obtain two unknown samples in small beakers or vials. Record the mass of each sample.
Weigh 100mg of ethylisovalerate directly into each sample.
Add ~50 mL of methylene chloride to the sample and stir for 30 s.
Transfer the slurry to the vacuum apparatus and filter the extract. Turn the vacuum off when
the filtering is finished.
6. Rinse the beaker with an additional 20 mL of methylene chloride and wash the filter cake.
Repeat again. (Due to evaporation, there will be less then 50 mL of filtrate in the flask.)
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Compiled Experiments
6
7. Transfer the solution to a graduated cylinder and dilute up to 50mL
8. Store the filtrate in a stoppered 125mL Erlenmeyer flask.
9. Repeat steps 6 through 11 for the other sample.
10. Obtain GC sample vials, label and fill vials ½ full with solution. Prepare two vials for each
solution.
Standar
ds
solution
s
Preparat ethyliso
ion of valerate
the
(mg)
standard
s
solution
alpha
pinene
Beta
pinene
Dlimonen
e
gamma
terpinen
e
Final
volume
(mL)
balance
toleranc
e (mg)
flask
toleranc
e (mL)
standard
s
(all
terpenes
)
alpha
pinene
Beta
pinene
Dlimonen
e
gamma
terpinen
e
unknowns
mass
of ethylisovaler
substrate (g)
ate (mg)
final solution error in final balance
volume (mL) volume (mL) tolerance
(mg)
Unknown 1
Unknown 2
Unknown 3
Data collection
1. Collect a chromatogram or total ion chromatogram (TIC) for the individual monoterpenes.
Researchers signature:
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Compiled Experiments
7
2. Record elution order. Is the elution order as expected?
3. Take three measurements each for the standard mix and the three unknown samples.
GC-MS
ethylisovaler alpha pinene Beta pinene D-limonene
gamma
ate
elution elution time elution time elution time terpinene
time (min)
(min)
(min)
(min)
elution time
(min)
standards (all
terpenes)
alpha pinene
Beta pinene
D-limonene
gamma
terpinene
GC
ethylisovaler alpha pinene Beta pinene D-limonene
gamma
ate
elution elution time elution time elution time terpinene
time (min)
(min)
(min)
(min)
elution time
(min)
standards (all
terpenes)
alpha pinene
Beta pinene
D-limonene
gamma
terpinene
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Compiled Experiments
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4. Analyze them on the Shimadzu GC-MS or the GC.
GC-MS settings
Method name: To be provided
Sample volume: 1μL
Temperature ramp: Tinit at 80 ºC; 70-150 at 20 ºC per minute; 150-300 at 80 ºC per minute
and hold for 1 minute
Column: Shimadzu SHRXI-5MS (30m x 0.32mm x 0.25μm). The stationary phase for this
type of column is 5% phenyl methyl siloxane.
Mobile phase: He(g).
Ion source temp: 200°C
Solvent cut time: 1.2 min
Start data at 1.5 min stop data at 4.0 min
m/z range of: 40-250
split 500:1
GC settings
Method name: to be provided
Sample volume: 1μL
Temperature ramp: Tinit at 80 ºC; 70-150 at 20 ºC per minute;150-300 at 80 ºC per minute
and hold for 1 minute
Column: Agilent HP-5 (30m x 0.32mm x 0.25μm). The stationary phase for this type of
column is 5% phenyl methyl siloxane.
Method name:
Start data at 1.3 min stop data at 4.0 min.
Mobile phase: He(g).
file types: .txt, .csv, .xls
pressure 9.5 PSI
split 100:1
Researchers signature:
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Instructor Signature:
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Compiled Experiments
9
Data Analysis
1. Find the peak area for each analyte and the internal standard
2. Find the average response factors for each standard with error.
1. Using the response factors determine the concentration of unknown in the solutions in mg
of monoterpene/g of vermiculite.
2. Propagate the error to determine the confidence intervals for your unknowns.
3. Once you have calculated the unknown concentration, show an instructor your results in
person or via email in order to receive the samples’ actual concentration.
4. Compare your unknowns using a two sample t-test
5. Compare the results from your two instruments using a paired t-test
6. Compare your results to the actual concentrations using a literature t-test
Lab Report
1. Results: Complete the 4 tables provided in the informal report. Modify or duplicate if
necessary.
2. Results: Include table of response factors with error.
3. Discussion: Basic theory behind the analytical technique used in this experiment.
4. Discussion: Evaluate the results of your t-tests and other tables. Since there are a number
and all of the results are listed in the tables, do not go through every single one. Instead,
summarize what the tables are telling us. Each table’s implications should be addressed
briefly. Make sure to address accuracy, precision, and differences between instruments.
5. Discussion: What could you do to improve your ability to determine an accurate unknown
concentration? What is your data telling you about where you had technical challenges
Where do you know had problems? The instruments can have some error, but they are
generally not the primary source.
Conclusion:
1.
2.
3.
4.
5.
What did the group like about the instructors’ facilitation?
What did the group do well in regards to the process skill of the experiment?
How can the group improve in regards to the process skill of the experiment?
What are three things you learned today?
What do you still have questions about?
References
1. Harris, D.C. Quantitative Chemical Analysis, 7th ed.; W.H. Freeman & Co.: NewYork, 2007;
pp 90-92, 474-484 and 528-546.
Researchers signature:
9/26/16 12:35 PM
Instructor Signature:
9/26/16 12:35 PM
Lab Report
1. Results: Complete the 4 tables provided in the informal report. Modify or duplicate if
necessary
2. Results: Include table of response factors with error.
3. Discussion: Basic theory behind the analytical technique used in this experiment.
4. Discussion: Evaluate the results of your t-tests and other tables. Since there are a number
and all of the results are listed in the tables, do not go through every single one. Instead,
summarize what the tables are telling us. Each table’s implications should be addressed
briefly. Make sure to address accuracy, precision, and differences between instruments.
5. Discussion: What could you do to improve your ability to determine an accurate unknown
concentration? What is your data telling you about where you had technical challenges
Where do you know had problems? The instruments can have some error, but they are
generally not the primary source.

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