11
EXP NUMBER
EXPERIMENT/SUBJECT
DATE
NAME
Spectrometrie determination of
COURSE & SECTION NO.
020
LAB PARTNER
LOCKERIDESK NO.
Claire colgrove
procedure
beverage whose absorbances
overlap or dont overlap
1) select beverage, record name,
flavor, serving Sho, volume
Conc (GlmL
Abs (A
LOOSAU
0.145 AU
0.30SAU
23
0.482 AU
a.632 AN
0,804 AU
10.23ZAU
FO.JOSAU
al water
multi component
system
710511S
ove
oschen Schmidt & Angeinna
Lab Purpose: To Quentify food ducs Data/observations
Beverage: Gatorade
Flavor Orange
Serving Size: 1 bottle
Volume: 591ML
2) using conc
stock of dye H I Dyes: Yellow S, Red 40
prepare standard solutions in
dye H I yellow 5
max
graduated cylinder
Volume added
0.000 (0:1) 424.Snm
3) repeat for dye #2
2 mL sul
424.5 nm
4me sol
424.5 nm
4) Prepare spectrometer as usual (amax)
GML Soi
424.5mm
8mL sol
4245 nm
SOT
424.5 nm
5) Record Abs for std curve points Tome
14245m
(obtain all dye HI
6 points)
beverage
0.424,50m
6 obtain absorbonce rave for
dye #2 Red 40
volume added
End (GMC) a max Abi (AU)
beverage
9.000 COD)
2 ml Solu
7) Repeat for dye #2
4 ml sol
Solso nm
6ml sol
sol.so nm
0.438 AU
Experiment H2
8m sol
Solso nm
0.57 SAU
lomi sol
sol.50 nm
0.818 AU
1) Std dilutions are already made
I beverage
sol.sonm
0.124 AV
2) obtain a max for yellows
s red 3 using its PPM
3) Record Abs vawes for all y6
slds (4 data points) and at
y6 l max
1o0SAU
sol-soam
sol.se an
0. 14 2 PU
10.300 AU
니
4) Record Abs values for all Y6
stas (u dota pis) at R3 lmax
sauny
muy uume 711415
DATE
WITNESS/TA
NOTE: INSERT DIVIDER UNDER COPY SHEET BEFORE WRITING
THE HAYDEN-MCNEIL STUDENT LAB NOTEBOOK
Imax
conc (g/mL
Abs (Au)
-0.0SAU
0.145 AU
0.30SAU
3
Beverage: Gator
Flavor Orange
Serving Size: 1 bottle
volume: 591ML
Dyes - Yellow 5, Red 40
dye # 1 yellow 5
Volume added
0.000 (17) 424.Sam
2 mL sul
424.5 nm
4 me sol
424.5 m
GML Sol
424.5nm
8m. Sol
424.5 nm
S Tom
1424.5 nm
beverage
14245 AM
0.484.5mm
dye #2 Red 40
volume added
Q-000 CAD
End (gh() & max Abi (AU)
2 ml solu
sol-soam
solsem
0.142 AU
4ml sol
10.300 AU
GML sol
10.438 AU
8ml sol
Solso nm
0.57 SAU
sol.so nm
loml Sol
Je
0.818 AU
beverage sol.sonm
0.124 AV
0.482 AU
0.632 AN
0,804 AU
SO
10.23ZAU
10.00 SAU
a wotex
=o0SAU
Solso nm
sol.so nm
0.25W
0,170 PW
Yellow
Conc avs 96
v) 15ppm 0,626 AU
loppm ) 0.434 NU
5ppm
0,226
idi
ny nown 0,29960
mas
4%0.56
/////////
////////
////
3
- Araz
Ped 3
conc
ars a 16
abs ar3
ispon
0,32SAU
lopen
0.346 AU
0, 198 AU
0.140RU 0.6391
sppon
0,0TAU
DI
To 11.006 AU
unknown llllllllll/10420 AU
amay II I 529.52m
6) unknown IAZ
Analysis
Prepare and print the following graphs using Excel or the LabQuest unit, as your instructor
1
directs
Beverage graphs (identity & quantify the food dye in your beverage)
Graph A Absorbance at the max for the food dye in your beverage versus dye concentration
Graph B: Absorbance at the Amax for the 2nd food dye in your beverage (if any) versus concentration
Yellow 6 / Red 3 graphs (quantify the dyes with & without considering "interference"):
Graph 1: Absorbance at the max for Yellow 6 vs Yellow 6 concentration
Graph 2: Absorbance at the max for Red 3 vs Yellow 6 concentration
Graph 3: Absorbance at the max for Yellow 6 vs Red 3 concentration
Graph 4: Absorbance at the max for Red 3 vs Red 3 concentration
Note that Absorbance is conventionally on the (y-axis) and concentration on the (x-axis).
2.
Include your measurement for water as a data point in all graphs. Record the best-fit line for each
graph; there should be a linear relationship between absorbance and concentration, as dictated by
Beer's Law
Rearrange Beer's Law (A = &c, where b=1) to
E = A/C
(4)
and note that A/c = Aylax on your graph, thus [ε = slope. As the absorbance of a given species has
a different & at each wavelength of interest, each of your plots yields you a specific value for ε for
that dye at one particular wavelength.
Label your graphs well so that the species and wavelength are clear (informative title & axes labeling).
3.
You should confirm that the absorption from one food dye in your beverage does not overlap
appreciably with the absorption from another, thus the concentration of each dye in the beverage
solution may simply be calculated in a similar fashion. Take care to select ε correctly (i.e., from the
appropriate standard curve). Determine the % dye by mass and the mass of dye per serving.
4.
Next, calculate the concentration of FD&C Yellow 6 and Red 3 in your unknown mixture using
Equation 4, as well. Be careful to select the correct ε to use for your calculations.
Performing this “simple” calculation assumes that the absorption from FD&C Yellow 6 does not
overlap appreciably with the absorption from Red 3.
5.
In reality, as you'll see when you look at your data from this experiment (Part III), the absorption
spectra for FD&C Yellow 6 and Red 3 do indeed overlap to some extent. The most accurate analysis
of the data, then, will take this into account. In equation form, this may be expressed as:
(5)
Aunk = AY6 + ARed3
To account for this interference, solve the following simultaneous equations for the unknown
concentrations of Yellow 6 and Red 3 (Cy6 and Cred3 respectively).
(6a)
EY6@amax(Y6)CY6 + ERed3@amax(Y6) Cred3
Aunk@amax(Y6)
(6b)
= Ey6@imax(Red3) Cve + Ered3@ảmax/Red3,Cred3
Aunk@max(Red3)
63
POSTLAB DISCUSSION - MULTI-COMPONENT SYSTEMS
This form should be filled out using PEN only. Mistakes should be crossed through with a single line only
Note: all calculations must
be shown in lab notebook pages to receive credit
TABLE Y DYES FOUND IN Gatorade
(input name of selected beverage)
Dye Color
max (nm)
z atamax For % Dye By
Mass of Dye
Dye Color
Mass
Per Serving
yellows
424.50
ned 40 sol.so
TABLE 2: YELLOW 6 & RED 3 DYES
Dye Color amax (nm)
e at Imax For
Concentration
Concentration
& atumax For
Yellow 6
Red 3
(ppm), No (ppm), With
Interference* Interference *
Yellow 6 480.so
Red 3
529.52
*This calculation assumes there is no spectral interference (overlap) between Yellow 6 and Red 3;
concentration is calculated simply using the equation of the line at each respective Imax-
**This calculation accounts for the spectral interference that does exist between Yellow 6 and Red 3;
concentration is calculated using a system of two equations to solve for two unknowns.
1.
Which of the following statements are TRUE about the extinction coefficient, €? (Check all that apply.)
a.
b.
C.
The extinction coefficient is a measure of the absorbance of a 1.0 M solution of a given species.
The extinction coefficient can be obtained from the slope of a Beer's Law plot.
The extinction coefficient increases as path length increases.
The extinction coefficient is both wavelength and species dependent.
For a given chemical species, the extinction coefficient changes with the wavelength of light.
d.
e.
2. A student is preparing a calibration curve for the absorbance of a colored sports drink. However, the student
does not realize that the color of the sports drink is actually composed of two different species of food dye, both
of which absorb at the wavelength chosen for the curve. What will happen to the student's calibration curve?
a. The data will be skewed high; the calibration curve has positive error.
b. The data will be skewed low; the calibration curve has negative error.
c. There will be no effect on the data; the calibration curve remains valid.
d. The data will be skewed high but, since the error is consistent for all points, the calibration curve
remains valid
Analysis
Prepare and print the following graphs using Excel or the LabQuest unit, as your instructor
1
directs
Beverage graphs (identity & quantify the food dye in your beverage)
Graph A Absorbance at the max for the food dye in your beverage versus dye concentration
Graph B: Absorbance at the Amax for the 2nd food dye in your beverage (if any) versus concentration
Yellow 6 / Red 3 graphs (quantify the dyes with & without considering "interference"):
Graph 1: Absorbance at the max for Yellow 6 vs Yellow 6 concentration
Graph 2: Absorbance at the max for Red 3 vs Yellow 6 concentration
Graph 3: Absorbance at the max for Yellow 6 vs Red 3 concentration
Graph 4: Absorbance at the max for Red 3 vs Red 3 concentration
Note that Absorbance is conventionally on the (y-axis) and concentration on the (x-axis).
2.
Include your measurement for water as a data point in all graphs. Record the best-fit line for each
graph; there should be a linear relationship between absorbance and concentration, as dictated by
Beer's Law
Rearrange Beer's Law (A = &c, where b=1) to
E = A/C
(4)
and note that A/c = Aylax on your graph, thus [ε = slope. As the absorbance of a given species has
a different & at each wavelength of interest, each of your plots yields you a specific value for ε for
that dye at one particular wavelength.
Label your graphs well so that the species and wavelength are clear (informative title & axes labeling).
3.
You should confirm that the absorption from one food dye in your beverage does not overlap
appreciably with the absorption from another, thus the concentration of each dye in the beverage
solution may simply be calculated in a similar fashion. Take care to select ε correctly (i.e., from the
appropriate standard curve). Determine the % dye by mass and the mass of dye per serving.
4.
Next, calculate the concentration of FD&C Yellow 6 and Red 3 in your unknown mixture using
Equation 4, as well. Be careful to select the correct ε to use for your calculations.
Performing this “simple” calculation assumes that the absorption from FD&C Yellow 6 does not
overlap appreciably with the absorption from Red 3.
5.
In reality, as you'll see when you look at your data from this experiment (Part III), the absorption
spectra for FD&C Yellow 6 and Red 3 do indeed overlap to some extent. The most accurate analysis
of the data, then, will take this into account. In equation form, this may be expressed as:
(5)
Aunk = AY6 + ARed3
To account for this interference, solve the following simultaneous equations for the unknown
concentrations of Yellow 6 and Red 3 (Cy6 and Cred3 respectively).
(6a)
EY6@amax(Y6)CY6 + ERed3@amax(Y6) Cred3
Aunk@amax(Y6)
(6b)
= Ey6@imax(Red3) Cve + Ered3@ảmax/Red3,Cred3
Aunk@max(Red3)
63
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