Red 40 Lab
Determining Red 40 Concentrations Using Absorption with Beer’s Law
Introduction
I like color and enjoyed learning about wavelengths and the spectrum of light, so I considered incorporating something related to that into my Internal Assessment. We also had just used concentrations in our Group 4 Project, so when I found an experiment that dealt with both of these I thought it was a great idea. This experiment is not completely original; the basic concept has been used multiple times. It uses Beer’s Law:
· A is light absorbance
· is “molar absorptivity with units of L mol-1 cm-1”
· l is the length of the cuvette in centimeters
· c is the concentration of the solution in mol L-1
The relationship between absorbance and concentration …show more content…
found in Beer’s Law is then applied to the experimental values of light absorption gained through the use of a colorimeter, which sends pulses of light through the substance, and the levels of concentration attached to these absorption values to create a linear equation, which can then be used to determine the concentrations of substances when only their absorption value is known.
I saw a similar experiment done on the internet, but I used a different wavelength setting on the colorimeter because that worked better to get my data and I found my own substances to test. I created my own procedure as well. I chose this method because it was an efficient and intelligent way to reach fairly accurate conclusions about the concentrations; I chose the dye red 40 because it is one of the most common dyes used, often in food.
The concentrations of red dye 40 are important because it has been shown to be slightly carcinogenic, among other things, in various studies. It is not extremely dangerous or highly deadly but can have a negative impact on health, so it is good to find which products we use daily have higher concentrations of this widely-used dye.
Research question
What are the concentrations of red 40 in different drinks?
Variables Independent Variable: Concentration · 10mL and 25mL volumetric pipettes (unc ±0.03 mL and ±0.04 mL respectively
· 5 mL graduated pipette (unc ±0.05 mL)
· 100 mL volumetric flasks (unc ±0.16 mL)
Dependent Variable: Absorption · Colorimeter
· LabQuest (unc ±0.001)
Controlled Variables: · Red 40 and distilled water as substances
· Reused pipettes after rinsing with each concentration
· Lab environment (similar pressure and temperature)
Materials Material Quantity measured Absolute uncertainty Percentage uncertainty 10mL volumetric pipette 10.00 ±0.03 0.30%
25mL volumetric pipette 25.00 ±0.04 0.16%
5 mL graduated pipette 1.60 ±0.05 3.10%
100 mL volumetric flasks 100 ±0.16 0.16%
Digital Milligram Scale 0.0397 g ±0.0001 g 0.25%
Red 40 0.0397 g - -
Diluted water - - -
Red Powerade - - -
Fresa Fanta - - -
Cherry Crystal Light - - -
Black Raspberry Sparkling Ice - - -
Vernier Colorimeter - - -
Vernier LabQuest 2 - ±0.001 -
Safety
There are various health concerns that have been linked to food dyes such as Red 40. Studies have shown it is an allergen, a carcinogen, and may impact other health aspects negatively as well. I wore gloves, safety goggles, and an apron during this experiment to adhere to safety guidelines.
Method
Before I could actually begin my trials, I had to create my concentrations.
I had to determine, using moles of red 40 (which had a molar mass of 496.42 g/mol) and the desired starting concentration of 0.0008 mol/, how many grams of red 40 I would need. It came out to 0.0397 grams (g). Therefore, I first weighed out 0.0397 g of red 40 on the milligram scale. Next, I carefully shook out the 0.0397 g of Red 40 into a 100 volumetric flask and added diluted water to the flask until the meniscus was at the 100 mark. Then I placed the cap on the flask and put it upside down and right-side up, mixing it completely. I also had to complete the calculations for the next concentrations using =; I did this for serial dilutions of .0008 mol/, .0006 mol/, .0004 mol/, .0002 mol/, and .0001 mol/ concentrations. How many of current concentration necessary for the next desired …show more content…
concentration
Current concentration
Next desired concentration
Flask size in
For example:
Current concentration
Using the pipettes, I placed the required amount of the parent dilution (0.0008) into a new 100 volumetric flask and added diluted water until the meniscus was at the 100 line; again, I mixed it thoroughly. I repeated the process of adding the previous concentration to a new 100 flask and adding diluted water and then mixing it to get to the right concentrations until I had created each desired concentration. After I had created my specific concentrations, it was time to determine their absorbency. I acquired a LabQuest, turned it on, and connected the colorimeter to Channel 1. When researching I had found that 470nm was supposed to work best but after having some problems, I called the company and the lab tech suggested using 565nm so I used that for each trial. I then filled a cuvette about 85% full of diluted water, placed it into the colorimeter, and closed the lid. Then I pressed the “Calibrate” button to calibrate the colorimeter. Next, I removed the cuvette of diluted water and pressed the “start” button on the LabQuest. For each of my five concentrations, I placed the cuvette with my specific concentration within the colorimeter, closed the lid, and pressed “keep” once the reading had stabilized on the Lab Quest. I completed three trials for each concentration to improve accuracy and averaged them when completing the math processes necessary.
Once I had all of my data points, I entered them into my calculator to determine the line of regression, which was using the relationship between concentration and absorbency from Beer’s Law. I then repeated basically the same procedures with my “mystery” substances to get their absorbencies. I placed a sample of each into the cuvette, closed the lid, and recorded the absorbency value once it stabilized. Finally, I placed the absorbency quantities for each of the “mystery” substances as the “y” values in my linear regression line to determine their concentrations.
Results
Concentration (mol/) Absorption
0.0008 Trial 1 - 0.865
Trial 2 - 0.861
Trial 3 - 0.861
0.0006 Trial 1 - 0.787
Trial 2 - 0.787
Trial 3 - 0.787
0.0004 Trial 1 - 0.673
Trial 2 - 0.672
Trial 3 - 0.673
0.0002 Trial 1 - 0.460
Trial 2 - 0.463
Trial 3 - 0.464
0.0001 Trial 1 - 0.285
Trial 2 - 0.289
Trial 3 - 0.290
y = absorbency x = concentration
Substance Absorption
Red Powerade Trial 1 - 0.542Avg: 0.542
Trial 2 - 0.544
Trial 3 - 0.541
Fresa Fanta Trial 1 - 0.560Avg: 0.559
Trial 2 - 0.555
Trial 3 - 0.563
Black Raspberry Sparkling Ice Trial 1 - 0.642Avg: 0.645
Trial 2 - 0.645
Trial 3 - 0.647
Cherry Crystal Light Trial 1 - 0.554Avg: 0.553
Trial 2 - 0.555
Trial 3 - 0.549
Substance Red Powerade Strawberry Fanta Black Raspberry Sparkling Ice Cherry
Crystal Light
Concentration grams/ I used my linear regression equation and the absorption of the substances to determine their concentrations:
Data analysis:
When creating the concentrations of red 40, as mentioned previously, I used a serial dilution.
These are the resulting uncertainties:
To create 0.0008: 0.25% from the digital scale + 0.16% from the 100 flask = 0.41% unc
0.0008 → 0.0006: 0.41% from previous dilution + 3(0.16)% from using the 25 volumetric pipette + 0.16% from putting it into another 100 volumetric flask = 1.04% unc
0.0006 → 0.0004: 1.04% from previous dilution + 2(0.16)% from using the 25 volumetric pipette + 0.30% from using the 10 volumetric pipette + 1.00% for using the 5 graduated pipette + 3.10% from using the 5 graduated pipette for 1.60 + 0.16% for placing it into another 100 volumetric flask = 5.92% unc
0.0004 → 0.0002: 5.92% from previous dilution + 2(0.16)% from the 25 volumetric pipette + 0.16% for placing it into another 100 volumetric flask = 6.4% unc
0.0002 → 0.0001: 6.40% from previous dilution + 2(0.16)% from the 25 volumetric pipette + 0.16% for putting it into another 100 volumetric flask = 6.88% unc
Total uncertainty for this serial dilution is 6.88%
The LabQuest used also had an uncertainty of 1.00% but this is not factored into the final results
Discussion
Literacy values could not be found for the concentrations of the drinks, so there is nothing to compare to check accuracy.
The line is not perfectly linear so it can easily be inferred that there were some anomalous results; this could be due to random errors as shown in the uncertainty calculations shown above or even a systematic error if I did not wait as long as I should have for the values on the LabQuest to stabilize (I generally took the average value between 5-10 seconds after closing the top of the colorimeter).
Evaluation
Some of the most significant errors I may have made were:
· Percentage error due to uncertainties associated with lab equipment
Error in some degree is inevitable and I did try to use the most specific equipment possible; however, if I had better resources I would be better able to find more accurate results. The serial dilution I used also meant propagating uncertainties from each new concentration, which meant that if I had the first one wrong, they all would have been wrong. According to my previous calculations, I had a 6.88% total uncertainty, so the linear regression equation I found could have been off by that much.
· The LabQuest and colorimeter may have had problems. As mentioned previously the wavelength that should have been best would give me no readings unless the lid was open. Also, the numbers would rarely remain stable. I did try to take the value I believed to be the most stable and accurate but the equipment may have been off. This again could have skewed the linear regression equation because the data points for the y values may have been off if the absorbency readings were inaccurate.
Conclusion
By using the linear equation from the concentrations of red 40 I created, I found that · Red Powerade had mol/ of red 40
· Strawberry Fanta had mol/ of red 40
· Black Raspberry Sparkling Ice hadmol/ of red 40
· Cherry Crystal Light had mol/ of red 40 Knowing that red 40 may impact consumers’ health negatively, we can determine from this experiment that Black Raspberry Sparkling Ice, Strawberry Fanta, Cherry Crystal Light, and Red Powerade are, in that order, most to least dangerous for your health.
The values for the concentration of red 40 in these drinks ranged from mol/ to mol/, so it can be inferred that these are the ranges from which most companies use red dye 40 in their production. Since studies have shown that red dye 40 and other dyes have negative impacts upon health, and these are presumably the concentrations of the dye in products today, then it can be concluded that these ranges mentioned above of red dye 40 are too high to be safe for consumption. This is interesting to note as the concentrations are extremely small; perhaps this is why multiple other countries have banned or drastically reduced the use of artificial food dyes. They may be a cheaper method of making foods and beverages seem more appealing and appetizing, but even a small amount can be bad for health.
Further investigations
Some simple and obvious further investigations of this would be to find the concentrations of red 40 in different substances, or to find the concentrations of other dyes in different substances.
However, a more complex way of investigating this further would be to attempt to determine how much more harmful higher concentrations of red dye 40 would be; for example, does the 0.000129 difference between Black Raspberry Sparkling Ice and Red Powerade make a difference in how much the health is affected, or is that difference negligible? There is as of yet no specific health standard for red 40 that I could find. It could be ethically controversial to test this further process but it is nonetheless an interesting prospect to consider.
References
· "Beer's Law - Theoretical Principles." Teaching.shu.ac. N.p., n.d. Web. 11 Mar. 2017.
· Kristen Fischer. "Is Red Dye 40 Toxic?" Healthline. Ed. Peggy Pletcher. N.p., 2 Apr. 2015. Web. 11 Mar.
2017.
Introduction
I like color and enjoyed learning about wavelengths and the spectrum of light, so I considered incorporating something related to that into my Internal Assessment. We also had just used concentrations in our Group 4 Project, so when I found an experiment that dealt with both of these I thought it was a great idea. This experiment is not completely original; the basic concept has been used multiple times. It uses Beer’s Law:
· A is light absorbance
· is “molar absorptivity with units of L mol-1 cm-1”
· l is the length of the cuvette in centimeters
· c is the concentration of the solution in mol L-1
The relationship between absorbance and concentration …show more content…
found in Beer’s Law is then applied to the experimental values of light absorption gained through the use of a colorimeter, which sends pulses of light through the substance, and the levels of concentration attached to these absorption values to create a linear equation, which can then be used to determine the concentrations of substances when only their absorption value is known.
I saw a similar experiment done on the internet, but I used a different wavelength setting on the colorimeter because that worked better to get my data and I found my own substances to test. I created my own procedure as well. I chose this method because it was an efficient and intelligent way to reach fairly accurate conclusions about the concentrations; I chose the dye red 40 because it is one of the most common dyes used, often in food.
The concentrations of red dye 40 are important because it has been shown to be slightly carcinogenic, among other things, in various studies. It is not extremely dangerous or highly deadly but can have a negative impact on health, so it is good to find which products we use daily have higher concentrations of this widely-used dye.
Research question
What are the concentrations of red 40 in different drinks?
Variables Independent Variable: Concentration · 10mL and 25mL volumetric pipettes (unc ±0.03 mL and ±0.04 mL respectively
· 5 mL graduated pipette (unc ±0.05 mL)
· 100 mL volumetric flasks (unc ±0.16 mL)
Dependent Variable: Absorption · Colorimeter
· LabQuest (unc ±0.001)
Controlled Variables: · Red 40 and distilled water as substances
· Reused pipettes after rinsing with each concentration
· Lab environment (similar pressure and temperature)
Materials Material Quantity measured Absolute uncertainty Percentage uncertainty 10mL volumetric pipette 10.00 ±0.03 0.30%
25mL volumetric pipette 25.00 ±0.04 0.16%
5 mL graduated pipette 1.60 ±0.05 3.10%
100 mL volumetric flasks 100 ±0.16 0.16%
Digital Milligram Scale 0.0397 g ±0.0001 g 0.25%
Red 40 0.0397 g - -
Diluted water - - -
Red Powerade - - -
Fresa Fanta - - -
Cherry Crystal Light - - -
Black Raspberry Sparkling Ice - - -
Vernier Colorimeter - - -
Vernier LabQuest 2 - ±0.001 -
Safety
There are various health concerns that have been linked to food dyes such as Red 40. Studies have shown it is an allergen, a carcinogen, and may impact other health aspects negatively as well. I wore gloves, safety goggles, and an apron during this experiment to adhere to safety guidelines.
Method
Before I could actually begin my trials, I had to create my concentrations.
I had to determine, using moles of red 40 (which had a molar mass of 496.42 g/mol) and the desired starting concentration of 0.0008 mol/, how many grams of red 40 I would need. It came out to 0.0397 grams (g). Therefore, I first weighed out 0.0397 g of red 40 on the milligram scale. Next, I carefully shook out the 0.0397 g of Red 40 into a 100 volumetric flask and added diluted water to the flask until the meniscus was at the 100 mark. Then I placed the cap on the flask and put it upside down and right-side up, mixing it completely. I also had to complete the calculations for the next concentrations using =; I did this for serial dilutions of .0008 mol/, .0006 mol/, .0004 mol/, .0002 mol/, and .0001 mol/ concentrations. How many of current concentration necessary for the next desired …show more content…
concentration
Current concentration
Next desired concentration
Flask size in
For example:
Current concentration
Using the pipettes, I placed the required amount of the parent dilution (0.0008) into a new 100 volumetric flask and added diluted water until the meniscus was at the 100 line; again, I mixed it thoroughly. I repeated the process of adding the previous concentration to a new 100 flask and adding diluted water and then mixing it to get to the right concentrations until I had created each desired concentration. After I had created my specific concentrations, it was time to determine their absorbency. I acquired a LabQuest, turned it on, and connected the colorimeter to Channel 1. When researching I had found that 470nm was supposed to work best but after having some problems, I called the company and the lab tech suggested using 565nm so I used that for each trial. I then filled a cuvette about 85% full of diluted water, placed it into the colorimeter, and closed the lid. Then I pressed the “Calibrate” button to calibrate the colorimeter. Next, I removed the cuvette of diluted water and pressed the “start” button on the LabQuest. For each of my five concentrations, I placed the cuvette with my specific concentration within the colorimeter, closed the lid, and pressed “keep” once the reading had stabilized on the Lab Quest. I completed three trials for each concentration to improve accuracy and averaged them when completing the math processes necessary.
Once I had all of my data points, I entered them into my calculator to determine the line of regression, which was using the relationship between concentration and absorbency from Beer’s Law. I then repeated basically the same procedures with my “mystery” substances to get their absorbencies. I placed a sample of each into the cuvette, closed the lid, and recorded the absorbency value once it stabilized. Finally, I placed the absorbency quantities for each of the “mystery” substances as the “y” values in my linear regression line to determine their concentrations.
Results
Concentration (mol/) Absorption
0.0008 Trial 1 - 0.865
Trial 2 - 0.861
Trial 3 - 0.861
0.0006 Trial 1 - 0.787
Trial 2 - 0.787
Trial 3 - 0.787
0.0004 Trial 1 - 0.673
Trial 2 - 0.672
Trial 3 - 0.673
0.0002 Trial 1 - 0.460
Trial 2 - 0.463
Trial 3 - 0.464
0.0001 Trial 1 - 0.285
Trial 2 - 0.289
Trial 3 - 0.290
y = absorbency x = concentration
Substance Absorption
Red Powerade Trial 1 - 0.542Avg: 0.542
Trial 2 - 0.544
Trial 3 - 0.541
Fresa Fanta Trial 1 - 0.560Avg: 0.559
Trial 2 - 0.555
Trial 3 - 0.563
Black Raspberry Sparkling Ice Trial 1 - 0.642Avg: 0.645
Trial 2 - 0.645
Trial 3 - 0.647
Cherry Crystal Light Trial 1 - 0.554Avg: 0.553
Trial 2 - 0.555
Trial 3 - 0.549
Substance Red Powerade Strawberry Fanta Black Raspberry Sparkling Ice Cherry
Crystal Light
Concentration grams/ I used my linear regression equation and the absorption of the substances to determine their concentrations:
Data analysis:
When creating the concentrations of red 40, as mentioned previously, I used a serial dilution.
These are the resulting uncertainties:
To create 0.0008: 0.25% from the digital scale + 0.16% from the 100 flask = 0.41% unc
0.0008 → 0.0006: 0.41% from previous dilution + 3(0.16)% from using the 25 volumetric pipette + 0.16% from putting it into another 100 volumetric flask = 1.04% unc
0.0006 → 0.0004: 1.04% from previous dilution + 2(0.16)% from using the 25 volumetric pipette + 0.30% from using the 10 volumetric pipette + 1.00% for using the 5 graduated pipette + 3.10% from using the 5 graduated pipette for 1.60 + 0.16% for placing it into another 100 volumetric flask = 5.92% unc
0.0004 → 0.0002: 5.92% from previous dilution + 2(0.16)% from the 25 volumetric pipette + 0.16% for placing it into another 100 volumetric flask = 6.4% unc
0.0002 → 0.0001: 6.40% from previous dilution + 2(0.16)% from the 25 volumetric pipette + 0.16% for putting it into another 100 volumetric flask = 6.88% unc
Total uncertainty for this serial dilution is 6.88%
The LabQuest used also had an uncertainty of 1.00% but this is not factored into the final results
Discussion
Literacy values could not be found for the concentrations of the drinks, so there is nothing to compare to check accuracy.
The line is not perfectly linear so it can easily be inferred that there were some anomalous results; this could be due to random errors as shown in the uncertainty calculations shown above or even a systematic error if I did not wait as long as I should have for the values on the LabQuest to stabilize (I generally took the average value between 5-10 seconds after closing the top of the colorimeter).
Evaluation
Some of the most significant errors I may have made were:
· Percentage error due to uncertainties associated with lab equipment
Error in some degree is inevitable and I did try to use the most specific equipment possible; however, if I had better resources I would be better able to find more accurate results. The serial dilution I used also meant propagating uncertainties from each new concentration, which meant that if I had the first one wrong, they all would have been wrong. According to my previous calculations, I had a 6.88% total uncertainty, so the linear regression equation I found could have been off by that much.
· The LabQuest and colorimeter may have had problems. As mentioned previously the wavelength that should have been best would give me no readings unless the lid was open. Also, the numbers would rarely remain stable. I did try to take the value I believed to be the most stable and accurate but the equipment may have been off. This again could have skewed the linear regression equation because the data points for the y values may have been off if the absorbency readings were inaccurate.
Conclusion
By using the linear equation from the concentrations of red 40 I created, I found that · Red Powerade had mol/ of red 40
· Strawberry Fanta had mol/ of red 40
· Black Raspberry Sparkling Ice hadmol/ of red 40
· Cherry Crystal Light had mol/ of red 40 Knowing that red 40 may impact consumers’ health negatively, we can determine from this experiment that Black Raspberry Sparkling Ice, Strawberry Fanta, Cherry Crystal Light, and Red Powerade are, in that order, most to least dangerous for your health.
The values for the concentration of red 40 in these drinks ranged from mol/ to mol/, so it can be inferred that these are the ranges from which most companies use red dye 40 in their production. Since studies have shown that red dye 40 and other dyes have negative impacts upon health, and these are presumably the concentrations of the dye in products today, then it can be concluded that these ranges mentioned above of red dye 40 are too high to be safe for consumption. This is interesting to note as the concentrations are extremely small; perhaps this is why multiple other countries have banned or drastically reduced the use of artificial food dyes. They may be a cheaper method of making foods and beverages seem more appealing and appetizing, but even a small amount can be bad for health.
Further investigations
Some simple and obvious further investigations of this would be to find the concentrations of red 40 in different substances, or to find the concentrations of other dyes in different substances.
However, a more complex way of investigating this further would be to attempt to determine how much more harmful higher concentrations of red dye 40 would be; for example, does the 0.000129 difference between Black Raspberry Sparkling Ice and Red Powerade make a difference in how much the health is affected, or is that difference negligible? There is as of yet no specific health standard for red 40 that I could find. It could be ethically controversial to test this further process but it is nonetheless an interesting prospect to consider.
References
· "Beer's Law - Theoretical Principles." Teaching.shu.ac. N.p., n.d. Web. 11 Mar. 2017.
· Kristen Fischer. "Is Red Dye 40 Toxic?" Healthline. Ed. Peggy Pletcher. N.p., 2 Apr. 2015. Web. 11 Mar.
2017.