# 10054 chemistry

CHEM 10054 Experiment 3Experiment 3 Report Forms
Name
Student ID
Name
Student ID
At the start of the lab, show your completed pre-lab calculations to your instructor and obtain the
instructors initials.
Instructor Initials: ________________
Pre-Lab Calculations
Calculate the volume (mL) of 100.0 ppm food dye solution that is required to prepare 50.0 mL of 10.00
Volume of 100.0 ppm food dye solution =_____________mL
Results
Part A: Determination of the absorptivity and molar absorptivity of a food dye
Name and concentration of a food dye solution:____________________ & ________ ppm
Calculate the absorptivity and molar absorptivity of the food dye and determine the mean, standard
deviation and 95% confidence interval for molar absorptivity. Show your work on the next page.
Table 1. Absorbance, Absorptivity “𝑎” and molar absorptivity “𝜀” for a food dye
value
repeat absorbance measurements and absorptivity calculations
corrected
absorbance
𝑎
(ppm–1 ∙ cm–1)
𝜀
–1
(L mol ∙ cm–1 )
average 𝜀
(L mol–1∙ cm–1 )
standard
deviation of 𝜀
(L mol–1∙ cm–1 )
95% confidence
interval of 𝜀
(L mol–1∙ cm–1 )
Page 1 of 5
CHEM 10054 Experiment 3
The absorptivity “a” in units of L mg–1·cm–1 using 𝐴 = 𝑎𝑏𝑐 where 𝑏 is the path length in cm and 𝑐 is the
food dye concentration in ppm. Show a sample calculation.
The molar absorptivity “” in units of L mol–1·cm–1 using 𝐴 = 𝜀𝑏𝑐 where 𝑏 is the path length in cm and 𝑐 is
the food dye concentration in mol L–1. Note: Molar absorptivity can also be calculated by using this
equation: 𝜀 = 𝑎 × 1000 × 𝑀𝑀 where 𝑀𝑀 represents the molar mass of the food dye.
Calculate the 95% confidence interval with 𝑁 − 1 degrees of freedom for the molar absorptivity 𝜀.
𝑡𝑠
Hint: 𝑥̅ ±
where 𝑥̅ is the average value, 𝑠 is the standard deviation, 𝑁 is the number of data points
√𝑁
and 𝑡 is the value from the Student’s 𝑡-table at 𝑁 − 1 degrees of freedom.
Page 2 of 5
CHEM 10054 Experiment 3
Question 1: Is your average molar absorptivity 𝜀 accurate at the 95% confidence level? For this
calculation, you will need the literature or true value (𝜇𝑜 ; refer to the table in the introduction for this
value). Show a sample calculation.
Hint: 𝑡𝑐𝑎𝑙𝑐 =
|𝑥̅ −𝜇𝑜 |
𝑠
× √𝑁 and if 𝑡𝑐𝑎𝑙𝑐 > 𝑡𝑡𝑎𝑏𝑙𝑒 , then the results are statistically different.
Part B: Determination of the dilution factor for the unknown
Table 2. Mass of the unknown.
Unknown #
Mass vial + sample
Mass vial (dry)
Mass sample
= ___________
= ____________ g
= _____________ g
= ____________ g
Table 3. Determine the dilution factor for standard addition.
Trial #
Volume of the
unknown solution
(mL)
Volume of the
(mL)
e.g.,
10.00
50.00
Absorbance
Dilution factor
50.00/10.00 = 5.00
1
2
3
4
Note: From the correct trial, you will use the volume of the unknown and the volume of the volumetric
flask for the remainder of the experiment.
Page 3 of 5
CHEM 10054 Experiment 3
Unknown
Sample
Volume
(mL)
e.g.
10.00
1
Volume of 100.0 ppm Food Dye Solution Added
(mL)
Final
Initial
1.21
0.20
Concentration of
(ppm)
Blank-Corrected
Absorbance
2.02
0.510
1.01
0.00 mL food dye solution added
0.00
2
3
4
5
6
Plot and submit a graph of the absorbance (𝑦-axis) versus concentration of food dye (ppm) added (𝑥axis) using the data from Table 4. Calculate the equation of best straight line (linear least squares line
equation). Report the slope and y-intercept for this line. Attach the standard addition curve to this report
or submit it to the Dropbox.
Table 5: Analysis of standard addition curve
𝑚 = slope = ______________
𝐵⁄ = _____________
𝑚
𝐵 = intercept = ___________
Dilution factor = ____________
R2 = ___________
Use the standard addition curve data, to find the unknown concentration of food dye in the original
unknown sample (prepared from the coloured drink powder in the 100.0 mL volumetric flask). Show
[food dye] = ___________________ ppm
Page 4 of 5
CHEM 10054 Experiment 3
Calculate the mass of the food dye in the unknown in the 100.0 mL flask.
Mass food dye = _________________ g
Calculate the %(w/w) food dye in the unknown sample.
Unknown # = ________________
%(w/w) food dye = ____________ %
Calculate the % spike recovery using the absorbance data from flask 1 and 2 and the slope of the standard
% spike recovery = _______________%
Page 5 of 5
CHEM 10054 Experiment 3
Experiment 3 Report Forms
Name
Student ID
Name
Student ID
At the start of the lab, show your completed pre-lab calculations to your instructor and obtain the
instructors initials.
Instructor Initials: ________________
Pre-Lab Calculations
Calculate the volume (mL) of 100.0 ppm food dye solution that is required to prepare 50.0 mL of 10.00
Volume of 100.0 ppm food dye solution =_____________mL
Results
Part A: Determination of the absorptivity and molar absorptivity of a food dye
Name and concentration of a food dye solution:____________________ & ________ ppm
Calculate the absorptivity and molar absorptivity of the food dye and determine the mean, standard
deviation and 95% confidence interval for molar absorptivity. Show your work on the next page.
Table 1. Absorbance, Absorptivity “𝑎” and molar absorptivity “𝜀” for a food dye
value
repeat absorbance measurements and absorptivity calculations
corrected
absorbance
𝑎
(ppm–1 ∙ cm–1)
𝜀
–1
(L mol ∙ cm–1 )
average 𝜀
(L mol–1∙ cm–1 )
standard
deviation of 𝜀
(L mol–1∙ cm–1 )
95% confidence
interval of 𝜀
(L mol–1∙ cm–1 )
Page 1 of 5
CHEM 10054 Experiment 3
The absorptivity “a” in units of L mg–1·cm–1 using 𝐴 = 𝑎𝑏𝑐 where 𝑏 is the path length in cm and 𝑐 is the
food dye concentration in ppm. Show a sample calculation.
The molar absorptivity “” in units of L mol–1·cm–1 using 𝐴 = 𝜀𝑏𝑐 where 𝑏 is the path length in cm and 𝑐 is
the food dye concentration in mol L–1. Note: Molar absorptivity can also be calculated by using this
equation: 𝜀 = 𝑎 × 1000 × 𝑀𝑀 where 𝑀𝑀 represents the molar mass of the food dye.
Calculate the 95% confidence interval with 𝑁 − 1 degrees of freedom for the molar absorptivity 𝜀.
𝑡𝑠
Hint: 𝑥̅ ±
where 𝑥̅ is the average value, 𝑠 is the standard deviation, 𝑁 is the number of data points
√𝑁
and 𝑡 is the value from the Student’s 𝑡-table at 𝑁 − 1 degrees of freedom.
Page 2 of 5
CHEM 10054 Experiment 3
Question 1: Is your average molar absorptivity 𝜀 accurate at the 95% confidence level? For this
calculation, you will need the literature or true value (𝜇𝑜 ; refer to the table in the introduction for this
value). Show a sample calculation.
Hint: 𝑡𝑐𝑎𝑙𝑐 =
|𝑥̅ −𝜇𝑜 |
𝑠
× √𝑁 and if 𝑡𝑐𝑎𝑙𝑐 > 𝑡𝑡𝑎𝑏𝑙𝑒 , then the results are statistically different.
Part B: Determination of the dilution factor for the unknown
Table 2. Mass of the unknown.
Unknown #
Mass vial + sample
Mass vial (dry)
Mass sample
= ___________
= ____________ g
= _____________ g
= ____________ g
Table 3. Determine the dilution factor for standard addition.
Trial #
Volume of the
unknown solution
(mL)
Volume of the
(mL)
e.g.,
10.00
50.00
Absorbance
Dilution factor
50.00/10.00 = 5.00
1
2
3
4
Note: From the correct trial, you will use the volume of the unknown and the volume of the volumetric
flask for the remainder of the experiment.
Page 3 of 5
CHEM 10054 Experiment 3
Unknown
Sample
Volume
(mL)
e.g.
10.00
1
Volume of 100.0 ppm Food Dye Solution Added
(mL)
Final
Initial
1.21
0.20
Concentration of
(ppm)
Blank-Corrected
Absorbance
2.02
0.510
1.01
0.00 mL food dye solution added
0.00
2
3
4
5
6
Plot and submit a graph of the absorbance (𝑦-axis) versus concentration of food dye (ppm) added (𝑥axis) using the data from Table 4. Calculate the equation of best straight line (linear least squares line
equation). Report the slope and y-intercept for this line. Attach the standard addition curve to this report
or submit it to the Dropbox.
Table 5: Analysis of standard addition curve
𝑚 = slope = ______________
𝐵⁄ = _____________
𝑚
𝐵 = intercept = ___________
Dilution factor = ____________
R2 = ___________
Use the standard addition curve data, to find the unknown concentration of food dye in the original
unknown sample (prepared from the coloured drink powder in the 100.0 mL volumetric flask). Show
[food dye] = ___________________ ppm
Page 4 of 5
CHEM 10054 Experiment 3
Calculate the mass of the food dye in the unknown in the 100.0 mL flask.
Mass food dye = _________________ g
Calculate the %(w/w) food dye in the unknown sample.
Unknown # = ________________
%(w/w) food dye = ____________ %
Calculate the % spike recovery using the absorbance data from flask 1 and 2 and the slope of the standard
% spike recovery = _______________%
Page 5 of 5
CHEM 10054 Experiment 7
Experiment 7 Report Forms
Name
Student ID
Name
Student ID
At the start of the lab, show your completed pre-lab calculations to your instructor and obtain the
instructors initials.
Instructor Initials: ________________
Pre-Lab Calculations
Calibration Standard Preparation: Using three (3) volumetric flasks, prepare 50.00 mL of 10.0 ppm,
50.00 ppm and 100.0 ppm of a mixed Na, K, and Ca standard. What volume of 1000.0 ppm stock metal
standard is required to prepare the calibration standards?
Table 1. Target metal ion (Na, K, Ca) concentration preparations for calibration standards.
Stock Concentration
Aliquot Volume
Target Concentration
(ppm Metal ion)
(mL)
(ppm Metal ion)
(mL)
C1
V1
C2
V2
1
1000.0
10.00
50.0
2
1000.0
50.00
50.0
3
1000.0
100.00
50.0
Show a sample calculation.
Spiked Sample Preparation: You will analyze a diluted milk sample, but you will also need to perform
a spike recovery calculation (i.e., you will add a known volume of 1000.0 ppm metal ion stock) to your
unknown. The spiked concentration to the unknown is C2 or Cadded. Calculate the volume of 1000.0 ppm
stock to be added to 50.0 mL volumetric flask to produce C2 or Cadded concentrations of 20.00 ppm metal
ion.
Stock Concentration
(ppm metal ion)
C1
1000.0
Aliquot Volume
(mL)
V1
Target Concentration
(ppm metal ion)
(mL)
V2
20.00
50.0
Page 1 of 5
CHEM 10054 Experiment 7
Results
Record the determined concentrations for the analysis without the addition of La and those with La.
Indicate which data was collected by you and your lab partner. Attached the printed results of your
analysis to this report.
Data collected by you and your lab partner: without La or with La
(circle which applies)
Table 1: Complete the following table for the determined metal ion concentration.
Cup #
Sample
Na
ppm
K
ppm
Ca
ppm
Results without La
4
Diluted Milk Sample 1
5
Diluted Milk Sample 2
6
Diluted Milk Sample 3
7
Diluted Milk Sample 4 + spike
8
Blank – distilled water
9
50.00 ppm mixed calibration (Na, K, Ca)
Results with La
4
Diluted Milk Sample 1
5
Diluted Milk Sample 2
6
Diluted Milk Sample 3
7
Diluted Milk Sample 4 + spike
8
Blank – distilled water
9
50.00 ppm mixed calibration (Na, K, Ca)
Page 2 of 5
CHEM 10054 Experiment 7
Determine the average and standard deviation of the metal ion concentrations in the diluted milk
samples. Calculate the %spike recovery for each metal ion. Show a sample calculation.
Table 2: Metal ion concentration in diluted milk samples used to calculate %spike recovery.
Na
ppm
Results
K
ppm
Ca
ppm
without La
Average 𝐶𝑜𝑟𝑖𝑔𝑖𝑛𝑎𝑙 (ppm)
Standard Deviation 𝐶𝑜𝑟𝑖𝑔𝑖𝑛𝑎𝑙 (ppm)
%Spike Recovery =
with La
Average 𝐶𝑜𝑟𝑖𝑔𝑖𝑛𝑎𝑙 (ppm)
Standard Deviation 𝐶𝑜𝑟𝑖𝑔𝑖𝑛𝑎𝑙 (ppm)
%Spike Recovery =
Hint: %𝑠𝑝𝑖𝑘𝑒 𝑟𝑒𝑐𝑜𝑣𝑒𝑟𝑦 =
𝐶𝑠𝑝𝑖𝑘𝑒 −𝐶𝑜𝑟𝑖𝑔𝑖𝑛𝑎𝑙
𝐶𝑎𝑑𝑑𝑒𝑑
× 100%
Question 1: Are there any anomalous %spike recovery values? What do the anomalous %spike
recovery values indicate about the analysis?
Question 2: How do the %spike recovery values compare between the results obtained for the samples
with La and those without La? What does this indicate about the analysis?
Page 3 of 5
CHEM 10054 Experiment 7
Calculate the average metal ion concentration (ppm) in milk. Remember to include the dilution factor. If
the %spike recovery is below 75% or greater than 125%, then do not report the concentration of the
ion, but report as N/A. Show a sample calculation.
Your instructor will provide you with the actual metal ion concentration in your milk sample. Enter these
in the table below.
Table 3: Metal ion content in the milk samples.
Na
ppm
Sample
K
ppm
Ca
ppm
Milk Sample (without La)
Milk Sample (with La)
Actual
Calculate the %relative error for each metal ion, when possible. Show a sample calculation.
Table 4: %Relative Error in metal ion concentration.
Na
ppm
Sample
K
ppm
Ca
ppm
%relative error (without La) =
%relative error (with La) =
Hint: %𝑟𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝑒𝑟𝑟𝑜𝑟 =
𝑒𝑥𝑝.𝑣𝑎𝑙𝑢𝑒−𝑡𝑟𝑢𝑒 𝑣𝑎𝑙𝑢𝑒
𝑡𝑟𝑢𝑒 𝑣𝑎𝑙𝑢𝑒
× 100%
Question 3: What do these results imply about the sample matrices in this analysis?
Page 4 of 5
CHEM 10054 Experiment 7
Calculate the %relative error for each metal ion in the calibration check.
Table 5: Calibration check results.
Sample
Na
ppm
K
ppm
Ca
ppm
50.00 ppm standard (without La)
50.00 ppm standard (with La)
%relative error (without La) =
%relative error (with La) =
Question 4: How well did the BWB Flame Photometer hold its calibration?
Page 5 of 5
CHEM 10054 Experiment 9
Experiment 9 Report Forms
Name
Student ID
Name
Student ID
At the start of the lab, show your completed pre-lab calculations to your instructor and obtain the
instructors initials.
Instructor Initials: ________________
Pre-Lab Calculations
Calculate the concentration of caffeine prepared from a 1000 ppm caffeine stock solution if the following
aliquots are diluted into a 10.00 mL volumetric flask.
Table 1. Dilutions for the preparation of caffeine standards.
Stock Caffeine
Aliquot Vol. of Stock
Total volume
V1 (L)
C1 (ppm)
V2 (mL)
1
1000
100
10.00
2
1000
250
10.00
3
1000
350
10.00
4
1000
500
10.00
Caffeine Conc.
C2 (ppm)
If a 500 L aliquot of your sample is diluted to 10.00 mL, the dilution factor is……
Dilution factor=________________
Results
Part A: Preparation and Analysis of Standard Solutions and Samples
Enter the concentration, retention time and peak area for the samples of milli-Q water, theophylline (flask
Table 2. Summary table for HPLC data
Concentration
Compound
(ppm)
milli-Q water
1
caffeine
2
theophylline
3
Retention Time
(min)
Peak Area
(mAu∙s)
————-
Note: 1. The peak for milli Q water will be very small and around 2-2.26 min.
2. Please don’t panic if there are no peaks for flask 3 (adipic acid) or very small.
Page 1 of 4
CHEM 10054 Experiment 9
Enter the caffeine concentration of the standards and report caffeine and theophylline retention times
(tR), peak areas and peak widths.
Table 3. HPLC data for calibration caffeine standards and the unknown sample.
Caffeine
Conc.
(ppm)
#
tR
(min)
Caffeine
Area
(mAu∙s)
Width
(min)
tR
(min)
Theophylline
Area
(mAu∙s)
Width
(min)
Area Ratio
Acaf/Atheo
4
5
6
7
8
unknown
Prepare a calibration curve using external standards by plotting the peak area of caffeine as a function of
caffeine concentration and a calibration curve using an internal standard by plotting peak area ratios of
Acaffeine/Atheophylline as a function of caffeine concentration. Attach the calibration curves to your report or
submit to the Dropbox. Apply a trend line to the data and report the trend line equations and R2 values.
Note: Remember that these are not Beer’s law plots and as such the intercepts may not go through (0,0);
therefore, do not force the trend lines through (0,0).
Table 4. Calibration curve data and caffeine concentration in the unknown sample.
Parameter
External Standards
Internal Standard
regression equation
R2 value
Caffeine concentration in
the diluted sample (ppm)
Caffeine concentration in
the original sample (ppm)
Calculate the concentration of the caffeine unknown in diluted and original solutions. Remember to adjust
the FINAL concentration for any dilution factors. Show your work for either the external or internal
standard calibration curve.
diluted unknown caffeine concentration (ppm) =________________
original unknown caffeine concentration (ppm) =________________
Page 2 of 4
CHEM 10054 Experiment 9
Calculate the resolution 𝑅𝑠 of caffeine and theophylline (use one set of data from flask 4 to 7). Show your
calculation.
𝑅𝑠 =
2[𝑡𝑅 (𝑐𝑎𝑓𝑓𝑒𝑖𝑛𝑒) − 𝑡𝑅 (𝑡ℎ𝑒𝑜𝑝ℎ𝑦𝑙𝑙𝑖𝑛𝑒) ]
𝑤𝑐𝑎𝑓𝑓𝑒𝑖𝑛𝑒 + 𝑤𝑡ℎ𝑒𝑜𝑝ℎ𝑦𝑙𝑙𝑖𝑛𝑒
where 𝑡𝑅 is the retention time in minutes
𝑤 is the peak width in minutes
Calculate the capacity factor for theophylline (use one set of data from flask 4 to 7). Show your
calculation.
𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝑓𝑎𝑐𝑡𝑜𝑟 = 𝑘𝐴 = (
𝑡𝑅 − 𝑡𝑀
)
𝑡𝑀
where 𝑡𝑅 is the retention time for theophylline
𝑡𝑀 is the retention time for the solvent peak (~2.66 min)
Question 1: What does the capacity factor tells you about theophylline?
Part B: UV spectra of adipic acid, caffeine and theophylline
Attach the UV spectra for the caffeine, theophylline and adipic acid or submit them to the Dropbox.
Examine the spectra and absorbance data at 254 nm and record the absorbance at 254 nm.
Table 5. Absorbance data for 10.00 ppm caffeine, theophylline and adipic acid at 254 nm.
Compound/Analyte
Absorbance at 254 nm
caffeine
theophylline
Page 3 of 4
CHEM 10054 Experiment 9
Question 2: If the HPLC detector only measures the absorbance at 254 nm, is adipic acid a good choice
to be used as an internal standard? Use the HPLC and UV data (Tables 4 and 5) to answer this question.
Question 3: Are there any other reasons why adipic acid may not have been an ideal choice as an
internal standard?
Part C: Calibration of a micropipette
Table 6. Calibration of the micropipette
Target Volume
(L)
100
Mass 1
(g)
Mass 2
(g)
Mass 3
(g)
Average Volume
(L)
250
350
500
1000
Question 5: Based on your results, is the micropipette calibrated? If not, then would it lead to
incorrect/inaccurate results?
Page 4 of 4
EXPERIMENT 1: Data Analysis (Part A)
Table 1: Name and Student Number
Student Name
Siddharth Thanki
Student Number
859800
Third Last Digit (X)
8
Second Last Digit (Y)
1
Last Digit (Z)
1
Table 2: Stock Solution Data
Stock Solution
Units
Mass
0.3811
g
Molar Mass
158.1
g/mol
Volume of Stock Solution
0.5000
L
Concentration
762.2
ppm
% Transmittance
Absorbance
Conc. Blank
(%T)
Signal
(ppm)
Table 3: Blank Data
Repeat Measurements
1
98.8
0.00524
0.587
2
99.1
0.00393
0.440
3
99.1
0.00393
0.440
4
98.8
0.00524
0.587
5
99.1
0.00393
0.440
6
98.1
0.00833
0.933
7
99.8
0.00087
0.097
8
99.1
0.00393
0.440
9
99.8
0.00087
0.097
10
98.1
0.00833
0.933
Average:
99.0
0.00446
0.499
Standard Deviation:
0.6
0.00254
0.285
Table 4: Parameters to be Determined or Calculated
Parameters
Value
Unit
Slope of Linear Calibration Curve (m )
0.00893
1/ppm
Absorptivity (a )
0.00893
L/(mg*cm)
1412
L/(mol*cm)
Molar Absorptivity (Ɛ)
Detection limit: (cm)
0.854
ppm
Limit of Quantification (LOQ or cQ)
2.85
ppm
Method Detection Limit (MDL)
0.925
ppm
Signal-To-Noise (S/N ) for the blank
1.75
no unit
%RSD for the blank
57.0
no unit
EXPERIMENT 1: Data Analysis (Part B)
Table 5: Calibration Standards and Unknown Samples Data
Volume of Stock in
100.0 mL
Concentration
%
Transmittance
(mL)
(ppm)
(%T)
Blank
0.00
0.00
98.98
Standard 1
0.50
3.81
92.5
Standard 2
1.00
7.62
85.3
Standard 3
2.00
15.24
72.0
Standard 4
5.00
38.11
43.1
Standard 4
5.00
38.11
45.7
Standard 4
5.00
38.11
44.9
Standard 5
10.00
76.22
21.6
Standard 6
15.00
114.33
9.3
Standard 7
25.00
190.55
7.3
Sample #1
0.00
61.8
Sample #2
0.00
41.1
Solution
Table 6: Calibration Curve Data
Concentration
CorrectedAbsorbance
(ppm)
(Abs)
Blank
0.00
0.0000
Standard 1
3.81
0.0294
Standard 2
7.62
0.0643
Standard 3
15.24
0.1383
Standard 4
38.11
0.3609
Standard 4
38.11
0.3354
Standard 4
38.11
0.3432
Standard 5
76.22
0.6605
Standard 6
114.33
1.0274
sample
Standard 7
190.55
1.1312
Table 7: Parameters to be Determined or Calculated
Parameters
Value
Unit
Limit of Linearity (LOL)
114.33
ppm
Dynamic Range (LOL – LOQ)
111.48
ppm
Slope of Linear Calibration Curve (m )
0.00893
1/ppm
Calibration Sensitivity (m )
0.00893
1/ppm
Average Corrected-Absorbance Standard 4
0.3465
no unit
Std. Dev. Corrected-Absorbance Standard 4
0.01304
no unit
Analytical Sensitivity (𝛾) for Standard 4
0.6851
1/ppm
Signal-To-Noise (S/N ) for Standard 4
26.58
no unit
%RSD for Standard 4
3.762
no unit
Concentration Sample #1
22.9
ppm
Concentration Sample #2
42.8
ppm
Absorbance
CorrectedAbsorbance
(Abs)
(Abs)
0.0045
0.0000
0.0339
0.0294
0.0688
0.0643
0.1428
0.1383
0.3653
0.3609
0.3399
0.3354
0.3477
0.3432
0.6649
0.6605
1.0318
1.0274
1.1357
1.1312
0.2089
0.2045
0.3864
0.3819
Calibration Curve
Concentration (ppm) vs. Corrected-Absorbance (Abs)
1.6000
Corrected Absorbance (Abs)
1.4000
1.2000
y = 0.0071x
R² = 0.9593
1.0000
0.8000
0.6000
0.4000
0.2000
0.0000
0.00
50.00
100.00
150.00
Concentration (ppm)
200.00
Concentration (ppm)
Linear Calibration Curve
Concentration vs. Corrected-Absorbance (Abs)
Corrected Absorbance (Abs)
1.2000
1.0000
0.8000
0.6000
y = 0.00893x
R² = 0.99950
0.4000
0.2000
0.0000
0.00
20.00
40.00
60.00
80.00
Concentration (ppm)
100.00
120.00
nce (Abs)
250.00
120.00
140.00
Table 1
Dilution calculations for food dye solutions
Food Dye Concentration
1
2
3
4
5
6
7
8
(ppm)
0.500
1.00
2.00
5.00
10.00
20.00
40.00
50.00
(mL)
50.00
50.00
50.00
50.00
50.00
25.00
25.00
25.00
9
Diluted unknown
100.0
10
Spiked unknown
100.0
Row
Table 2
Table 3
Volume of 100.0 ppm food dye stock solution used
50.00 ppm
40.00 ppm
Final Volume
14.50
24.50
(mL)
Volume of 100.0
ppm Food Dye
250.0
500.0
1.00
2.50
5.00
5.00
10.00
12.50
5.00 mL of
unknown +
0.00 mL of 100.0
ppm
5.00 mL of
unknown +
5.00 mL of 100.0
ppm
20.00 ppm
29.50
Initial Volume (mL)
2.00
14.50
24.50
12.50
10.00
5.00
Actual Food Dye
Concentration
(ppm)
50.00
40.00
20.00
BlankCorrected
Absorbance
Conc. Food Dye
(ppm)
0.004
0.022
0.023
0.022
0.020
0.022
0.023
0.023
0.022
0.101
0.556
0.581
0.556
0.505
0.556
0.581
0.581
0.556
Repeat analysis of 0.500 ppm food dye solution
Repeat
Measurement
1
2
3
4
5
6
7
8
Raw Absorbance
0.026
0.027
0.026
0.024
0.026
0.027
0.027
0.026
9
10
0.026
0.032
0.022
0.028
Average
0.027
0.023
0.573
x
0.002
0.052
Standard Deviation
s bl
Table 4
0.556
0.707
Data table for calibration curve, analysis of unknowns and spike recovery
1
2
3
4
5
5
5
5
5
Target Food Dye
Concentration
Raw
Absorbance
(ppm)
Exact Food
Dye
Concentration
(ppm)
Blank (DI water)
0.500
1.00
2.00
5.00
10.00
10.00
10.00
10.00
10.00
0.00
0.500
1.00
2.00
5.00
10.00
10.00
10.00
10.00
10.00
0.004
0.027
0.036
0.07
0.178
0.392
0.399
0.395
0.402
0.394
Average for 10.00
ppm food dye =
Standard deviation
for 10.00 ppm food
dye =
6
7
8
10.00
0.396
0.004
20.00
40.00
50.00
20.00
40.00
50.00
0.82
1.614
1.958
100.0 ppm
100.0
>2.5
Diluted Unknown
3.33
0.136
10
Spiked Unknown
Calibration Check[1]
5
10.00
8.41
0.337
10.00
0.395
9
Slope of graph
Diluted Unknown Conc
Spiked Unknown Conc
average [(avg. abs),(cal. Check)]
% difference
0.0396
3.33 ppm
8.41 ppm
0.392
0.357
5.00 ppm
102 %
% spike recovery
Table 5
Summary Table of Quality Parameters
Quality
Parameter
LOD or c m
Absorbance Data (A)
0.500 ppm Food Dye
Solution
0.156
ppm
0.520
0.17
ppm
ppm
Using 10.00 ppm
Calibration Standard
in Table 4
Using the
Slope of the
Calibration
Curve
0.0392
0.0396
1.95E+04
1.97E+04
LOQ or c Q
MDL
Summary of
Absorptivity
Absorptivity (a )
(L/mg•cm)
Molar Absorptivity
(e) (L/mol•cm)
Literature Molar
Absorptivity (e)
(L mol–1∙cm–1)
%Difference for e
Analytical Sensitivity
Dynamic Range
Signal to Noise Ratio
2.41E+04
-19.2
2.41E+04
-18.4
10 1/ppm
49.5 ppm
97.2
µL
µL
ml
ml
ml
ml
ml
ml
ml
10.00 ppm
100 ppm
5.00 ppm
2.00 ppm
34.50
37.00
38.00
29.50
34.50
37.00
5.00
2.50
1.00
10.00
5.00
2.00
A
Conc »
m
Conc. Food
Dye (ppm)
0.101
0.556
0.581
0.556
0.505
0.556
0.581
0.581
0.556
BlankCorrected
Absorbance
0.004
0.022
0.023
0.022
0.02
0.022
0.023
0.023
0.022
Concentration vs. Bl
0.03
0.025
Absorbance
Dye
Concentration
0.02
0.015
0.01
0.005
0
0
0
0.556
0.707
0
0.022
0.028
Slope of Linear Calibration Curve
Slope of
Graph (m)
0.0396
Exact Food
BlankDye
Corrected
Concentration
Absorbance
(ppm)
BlankCorrected
Absorbance
Blank
2.5
0.00
0.500
1.00
2.00
5.00
10.00
10.00
10.00
10.00
10.00
0.000
0.023
0.032
0.066
0.174
0.388
0.395
0.391
0.398
0.390
0.392
20.00
0.816
0.004
40.00
1.610
0.816
1.610
1.954
50.00
100.00
1.954
>2.5
>2.5
0.132
0.333
0.391
Limit of Linearity
50.00
Absorbance
2
0.000
0.023
0.032
0.066
0.174
0.388
0.395
0.391
0.398
0.390
1.5
1
0.5
0
0
Molar mass
496.42 g/mol
Concentration vs. Blank-Corrected Absorbance
y = 0.0396x
R² = 1.0000
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Concentration (ppm)
Blank-Corrected Absorbance vs. Concentration
y = 0.0396x
R² = 0.9996
10
20
30
Concentration (ppm)
40
50
60
Table 1
Absorbance, Absorptivity (a), & Molar Absorptivity (ε) for food dye
repeat absorbance measurements and absorptivity calcul
value
corrected absorbance
0.428
0.428
0.428
(a) (ppm–1 cm–1)
0.0428
0.0428
0.0428
(ε) (L mol–1cm–1)
2.12E+04
2.12E+04
2.12E+04
(average ε) (L mol–1cm–1)
2.13E+04
(standard deviation of ε) (L mol–1cm–1)
(95% confidence interval of ε) (L
mol–1cm–1)
44.4
55.1
21246.78 21246.78 21246.78
tcalc
ttable
142.6900205
2.776
rements and absorptivity calculations
0.430
0.428
0.0430
0.0428
2.13E+04
2.12E+04
2.13E+04
44.4
55.1
21346.06 21246.78
1.18E+01
Blank
absorbance
Cuvette
length
Repeat conc.
Molar mass
(Allura Red)
Number of
observations
Theoretical
molar
absorptivity
0.001
1.00 cm
10.00 ppm
496.42 g/mol
5
2.41E+04
Vol of 100.0 ppm Food Dye Added
Unknown
Conc of
Blank
Sample
Food Dye corrected
vol
Final
Initial
Absorbance
10.00
0.00
0.547
10.00
27.03
26.00
1.03
2.06
0.631
10.00
42.95
40.99
1.96
3.92
0.721
10.00
31.97
28.98
2.99
5.98
0.810
10.00
35.99
31.97
4.02
8.04
0.893
10.00
40.99
35.99
5.00
10.00
0.978
14.57274827
0.941725
Conc of Stock Food Dye
Volume of
volumetric
100.0 ppm
50.00 ml
Blank corrected Absorbance
1.200
1.000
0.800
y = 0.0433x + 0.547
R² = 0.9995
0.600
0.400
0.200
0.000
0.00
slope (m)
B/m
2.00
4.00
6.00
0.0433
12.6
Food Dye Conc
Spiked recovery
8.00
10.00
B
0.547
Dilution Factor 5.00
63.2
y = 0.0433x + 0.547
R² = 0.9995
10.00
12.00
Part B
Preparation of Zn Calibration Standards & Multivitamin Solution for Zn Analysis
BlankSolution
Exact Zn
corrected
(ppm Zn) conc (ppm) Absorbance % RSD Absorbance
1 Blank
0.00
0.0002
100
0.0000
2
0.5
0.500
0.1621
0.2
0.1619
3
1.0
1.00
0.3156
1.0
0.3154
4
1.5
1.50
0.4530
0.1
0.4528
5
2.0
2.00
0.5556
0.6
0.5554
diluted
6 vitamin
0.726
0.2234
0.5
0.2232
dil. Vit +
7 Zn spike
1.19
0.3654
0.6
0.3652
% spike recovery
Part C
92.4
Preparation of Zn/Multivitamin Solutions for Zn Analysis Using Standard Additio
Solution
dil. Vit. + 0
1 ppm Zn
Exact Zn
(ppm)
Absorbance % RSD
0.00
0.2532
0.5
dil. Vit. +
2 0.5 ppm Zn
0.50
0.3794
0.6
dil. Vit. +
3 1.0 ppm Zn
1.00
0.5143
0.1
dil. Vit. +
4 1.5 ppm Zn
1.50
0.6219
0.2
% spike recovery
101.7
BlankExact Zn
corrected
conc (ppm) Absorbance
0.000
0.0000
0.500
0.1619
1.000
0.3154
1.500
0.4528
2.000
0.5554
0.726
0.2232
1.19
0.3652
500 ppm
0.1 ml
Slope of
graph (m)
0.3073
dil. Conc.
dil. Factor
actual conc.
0.7270
100.0
72.70
0.5000
0.4500
Blank-corrected Absorbance
Zn stock
solution
Zn stock
n Solution for Zn Analysis
0.4000
0.3500
0.3000
0.2500
0.2000
0.1500
0.1000
0.0500
0.5
0.0000
0.000
0.7
0.6
dil. Vit. +
Zn spike
conc.
1.529 ppm
dil. Vit. Conc.
0.2482
1.020 ppm
0.5
Absorbance
Slope of
graph (m)
0.4
0.3
0.2
0.1
dil. Factor
100
dil. Factor
100.0
0
0.00
actual conc
152.9 ppm
actual conc
102.0 ppm
Conc vs. Blank-corrected Absorbance
0.5000
0.4500
y = 0.3073x
R² = 0.9994
0.4000
0.3500
0.3000
0.2500
0.2000
0.1500
0.1000
0.0500
0.0000
0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
1.600
1.40
1.60
Concentration (ppm)
y = 0.2482x + 0.2561
R² = 0.9980
0.00
0.20
0.40
0.60
0.80
1.00
1.20

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